MANILA BAY DELTA CHALLENGE · tao na maaring maapektuhan, direkta man o hindi. Sila ay nahahati sa dalawa, ang pormal at impormal na stakeholders, na mayroong magkaibang epekto sa

MANILA BAY DELTA CHALLENGE

MULTIDISCIPLINARY RESEARCH ON FLOOD PRONE AREAS IN

THE PAMPANGA DELTA

MAIN REPORT

MARCH 2014

Manila Bay Delta Challenge MAIN REPORT – MARCH 2014

Title

Subtitle

Type

Project initiated by

Supervisor

Project group (TU Delft)

Institute

Date

Manila Bay Delta Challenge

Multidisciplinary Research on Flood Prone Areas in

the Pampanga Delta

Multidisciplinary Project, TU Delft

Mr Evert de Boer (Filippijnengroep Nederland)

Mr Dick Groeneveld (Filippijnengroep Nederland)

Mr Angel Lontok Cruz (Major of Hagonoy, Bulacan,

Philippines)

Prof. dr. ir. Nick van de Giesen (TU Delft)

Joris de Vos – Water Resources Management

(Water Management)

Frans Willem Hamer – Sanitary Engineering (Water

Management)

Dirk Diederen – Hydrology (Water Management)

Ante Zorić – Water Management & Engineering

(Hydraulic Engineering)

Delft University of Technology

Faculty of Civil Engineering and Geosciences

March 2014


Partners

Delft University of Technology Bulacan State University

Universiteitsfonds Delft Royal Haskoning DHV

StuDevelopment fund Development Bank of the Philippines

Filippijnengroep Nederland


Preface

This report is the result of our multidisciplinary project on the flood prone delta of the rivers Pampanga and

Angat, north of Manila Bay in the Philippines. The project is the follow up of the collaboration of eight

municipalities in the delta: Macabebe, Masantol, Calumpit, Hagonoy, Paomong, Malolos, Bulacan and

Obando. Therefore, the mentioned will be the direct beneficiaries of this research. For us, the project is

part of the master track Water Management and the track Hydraulic Engineering at the Delft University of

Technology in the Netherlands.

At the start of the academic year in September, we started with the preparations. From the end of

November 2013 until halfway January 2014 we have been working in the Philippines, where we gathered

data from various institutions and where we performed field work. Back in the Netherlands, we have

focussed on modelling and processing of the data.

During our research, we have received a lot of help from numerous persons. First of all, we would like to

thank Angel Cruz for his commitment to the project and above all the inhabitants of the delta. You made us

feel welcome from the moment we arrived, and have been our watchful father, guide and host during our

stay.

The project would not have been possible without the efforts and initiatives of our Professor Nick van de

Giesen (TU Delft), Fons Nelen (Nelen&Schuurmans), Rien Dam (Deltares) and Evert de Boer and Dick

Groeneveld (FGN), especially during the preparations.

Seb, we would like to thank you as our mother in the field for your assistance, communication and

organisation of all our trips; of course your Marcy, who took us to places even he has never been before;

and April May, who gave us insight in the local conditions during the family visits.

We are very grateful to Dr. Mariano C. De Jesus and Engr. Romeo D. Robles from the Bulacan State

University, for the cooperation, hospitality and our research associates: Mara Pearl Domingo, Elmer Capiral

Libiran, Gerri Joseph Bernardo, Lorrie Mia San Pedro and Carl Stephen Rodriguez. It was most pleasant

spending time with you, both during the fieldwork and in our free time.

We will remember Maria Dolores C. Guevarra (DBP) and Wouter de Hamer (RoyalHaskoning-DHV) for their

hospitality and we would like to thank them for their advice and directions.

Of all the institutions we have visited we would like to thank in particular for their hospitality, fervour and

trust: Hilton T. Hernando (PAGASA), Victor B. Ubaldo (NDC-NEDA), Rommel Pajela (Health Office Hagonoy),

Marvin Reyes and Eugene C. Miguel (Municipality of Hagonoy) and Danilo A. Fajardo (Hydroterre and

HWD).

At last, we have to admit that we still feel a bit homesick because of you Susan, as you have been our

caring mother at the house and you have let us have a countless amount of tastes of the Filipino cuisine

and the stupendous Filipino warm heartedness.

Ante, Dirk, Frans Willem and Joris


Abstract

This document contains qualitative and quantitative descriptions of the Pampanga Delta with its flood

scenarios, assessment of initial consequences and possible future outcomes of proposed solutions.

Moreover, it has the goal to use as a guideline for sustainable development of the whole region, based on an

integrated water management approach.

Since olden times the Philippines deal with water related problems. In many low-lying areas floods are of

monthly occurrence, which cause socio economic catastrophes. This resulted in a promising collaboration

between eight municipalities in the delta. In this report, the initial situation has been described and

elaborated further in order to cope with the broad flooding issue.

In an integrated water management approach method one aims for social equity, economic efficiency and

environmental sustainability. In order to achieve these goals, numerous aspects have to be combined and in

the plenitude of choices, our team had decided to scout the delta by means of direct physical analysis and

through channel modelling with available and newly collected data. Due to temporal, logistical and financial

constraints, the team was limited to investigate the main rivers and relatively easy accessible areas.

The fieldwork consisted of doing interviews with those directly affected by floods, and salinity and depth

measurements on the rivers. These data have been used for land use validation, channel profile modelling

and scenario forecasting and are the main contributions to this report.

When coping with such a broad problem, one has to deal with various stakeholders. These are divided in

formal and non-formal stakeholders, which all have different impacts on the decision making process.

Rainfall data from gauges is available as catchment input for runoff forecasting. This has been elaborated for

the city of Zaragoza in order to illustrate the possibilities for data quantification and to determine the

accuracy of the existing measuring locations. The reliability of available rainfall runoff-height relations has

been explained and river discharge models have been established with the software toolkit SOBEK, based on

river profile measurements and calculated and technically supported assumptions for discharges. This model

– which embodies some important key principles of spatial and temporal flood intensity prediction – has

been compared to previously required flood maps. Based on a qualitative field research on the runoff

profiles, careful conclusions have been drawn on dredging locations.

Lowering the river bed level could have a considerable influence on salt intrusion in the delta and thus on

land use and faunal habitat displacement. High water levels and higher salinities in agricultural areas are

noted during tidal floods, therefore understanding the fresh versus salt water mixing process in the river

system is of high importance before dredging is taken into consideration.

Land use changes are notable in many of these low-lying areas. Agriculture changes to aquaculture and the

region that was well known for its rice production experiences switches in nature and extent of

employment. Moreover, the habitable area is gradually pushed more inland.

The floods also cause sanitary issues. A monthly inundated area often provokes illnesses as results of direct

exposure to the unhealthy surroundings. Furthermore, the overall water quality is far below the desired

level. Measures should be taken to improve many aspects of the initial sanitary circumstances.


When coping with floods, the community and individuals offer diverse ways of dealing with physical and

social problems. They show their vulnerability character when dealing with various disaster phenomena.

The structural and organizational possibilities of every barangay have to be researched, after which a new

plan can be proposed inside the scope of the vulnerability framework.

The idea is that new channel profiles and dikes can eventually be modelled and locations for

implementation of a primary defence system and (secondary) risk-based dike ring structures can be

designated. These final physical solutions in form of a sustainable delta defence system, combined with

flood resilient sanitary improvements can lead to considerable new social and economic opportunities for

the whole delta-populated community.


Buod

Ang dokumentong ito ay naglalaman ng deskripsyong kwalitatibo at kwantitatibo ng Delta ng Pampanga

kasama ng pagtukoy sa maaring mangyari tuwing babaha, at sa kung paanong paraan ito masususulusyonan.

Ito rin ay may layunin na maging alituntunin kung paano makakamit ang isang pangmatagalang kaunlaran sa

tulong ng integrated water management approach.

Dahil mula noong unang panahon, tubig ang isa sa mga problemang hinaharap ng Pilipinas. Sa mga

mabababang lugar, ang baha ay hindi na bago at kung minsan ay buwan-buwan ito kung mangyari, na

nagdudulot ng problemang pang sosyo-ekonomiko. Dahilan nito, nagsama-sama at nagtulong tulong ang

walong munisipalidad na nasa delta. Dito sa report na ito, makikita ang paglalarawan at pagpapaliwanag ng

inisyal na sitwasyon upang lalong maintindihan ang dahilan ng pagbaha.

Ang integrated water management approach ay isang paraan na naglalayon ng pagkakapantay pantay ng

lipunan , mahusay na ekonomiya at pagpapanatili ng kaunlarang pangkapaligiran.Upang maisakatuparan ito,

maraming aspeto ang kailangang pagsamasamahin, maraming pamimilian, at ang aming grupo ay

napagdesisyonan na pag-aralan ang delta sa pamamagitan ng direktang pagsuri dito, at sa pamamagitan ng

paggawa ng modelo ng daluyan ng tubig, bunga na rin ng mga panibagong datos na aming nakuha. Dahil sa

ilang mga limitasyon, naging limitado ang aming pag-iimbestiga sa mga pangunahing ilog at sa mga lugar

lamang na madaling makatuloy ang aming nasuri.

Ang fieldwork ay naglalaman ng mga interbyu sa mga taong direktang naapektuhan ng pagbaha, alat ng tubig

at pagsukat ng lalim ng tubig sa Ilog. Ang mga datos na ito ay ginamit para sa pagpapatunay ng gamit ng lupa,

ang paggawa ng modelo ng daluyan ng tubig at sa pagsasabi ng maaaring mangyari na magiging dulot ng

pagbaha ay ang pangunahing kontribusyon sa report na ito.

Sa pagharap sa ganitong problema, isang pangangailangan ay ang pagkakaroon ng koneksyon sa iba’t ibang

tao na maaring maapektuhan, direkta man o hindi. Sila ay nahahati sa dalawa, ang pormal at impormal na

stakeholders, na mayroong magkaibang epekto sa mga proseso ng pagdedesisyon.

Ang mga datos mula sa mga lugar na nagrerekord ng patak ng ulan ay magagamit upang makapagtala ng

maaring runoff sa hinaharap. Ito naman ay pinalawak para sa siyudad ng Zaragosa upang mailarawan ang

mga posibilidad para sa pagkwantipika ng mga datos at upang mapagalaman kung gaano mapagkakatiwalaan

ang mga umiiral na lugar na nagsusukat ng nasabing datos. Ang kredibilidad ng mga umiiral na relasyon sa

pagitan ng runoff dulot ng patak ng ulan at ang pagtaas ng tubig ay naipaliwanag at ang mga modelo ng pag-

agos ng ilog ay naisagawa sa tulong ng software na SOBEK, base sa mga sukat ng dimesyon ng ilog, at mga

umiiral na tiyorya at pagpapalagay ukol sa pag-agos. Ang modelong ito-- na nagbibigay representasyon sa

ilang mahahalagang alituntunin sa pagbibigay prediksyon sa magiging tindi ng baha—ay naikumpara sa mga

naunang kinakailangang flood maps. Base sa kwalitatibong pagsusuri sa runoff profiles, maingat na

konklusyon ang nagbigay ayon sa mga magiging dredging locations.

Ang pagbababa ng riverbed level ay mayroon ding impluwensya sa salt intrusion sa delta at pati na rin sa

gamit ng lupa at ang paglipat ng mga natural na tirahan ng mga hayop. Ang mataas na lebel at ang pag-alat

ng tubig sa mga lugar na pangagrikultura ay nakikita tuwing may baha, kung gayon ay nakikita ang

kahalagahan ng paghalo ng tubig tabang sa tubig alat bago ikonsidera ang dredging.


Ang pagbabago sa gamit ng lupa ay mapapansin sa karamihan ng mabababang lugar. Ang lupang pang-

agrikultural ay nagmistulang palaisdaan at ang mga lugar kung saan dati ay kilala sa pagtatanim ng palay ay

umunlad at natayuan ng mga establisyimentong pangkomersyo. Dahil dito, ang mga lugar na maaring tirahan

ay unti-unting napunta sa kalagitnaan ng mga ito.

Ang baha ay nagdudulot din ng mga isyung pangkalinisan. Ang mga lugar kung saan halos buwan-buwan

kung bumaha ay nagdudulot ng mga sakit dahilan ng pagkakalantad sa maduming kapaligiran. Isa pa, ang

pangkabuoang kalidad ng tubig ay masyadong mababa ayon sa tanggap na pamantayan. Marami pa ang

kailangang gawin upang mapabuti ang aspetong pangkalinisan.

Sa pagharap sa baha, ang komunidad at bawat indibidwal ay humahanap ng iba’t ibang paraan para sa mga

problemang pisikal at sosyal. Ang mga mamamayan ay nagpapakita ng iba’t ibang pamamaraan para

masolusyunan ang bawat sakuna. Ang mga posibilidad na struktural at organisasyonal ng bawat baranggay ay

metikolosong sinusuri, at pagkaraan ay panibagong plano ang maaring ipanukala sa loob ng naunang

balangkas.

Ang ideya na panibagong daluyan ng tubig at dike ang maaaring imodelo; at ang lokasyon para sa

implementasyon ng pangunahin at sekondaryang dikeng ipapalibot sa naturang lugar. Ito ang naisip naming

solusyon na nakadisenyo nang isang pangmatagalang delta defence system, kasama ng pagpapabuti sa

aspetong pangkalinisan ukol sa baha ay maaaring makagawa ng panibagong mga oportunidad na pang-

ekonomiya at sosyal para sa mga lugar at mamamayan na nakatira sa delta.


List of Figures Figure 1-1 - Project location ................................................................................................................................ 2

Figure 2-1: Time span of research ...................................................................................................................... 6

Figure 4-1 - Measuring river profiles ................................................................................................................ 12

Figure 4-2 - Depth measuring sonar with GPS .................................................................................................. 12

Figure 4-3 – Lorrie and Ante determine the approximate flow profile with tape-measure-weight ................. 13

Figure 4-4 - Diver ............................................................................................................................................. 13

Figure 4-5 - Diver and depth measuring locations ............................................................................................ 14

Figure 4-6 - Example: sonar depth measurements of point “S01” (Pampanga mouth) .................................... 15

Figure 4-7 - Bridge “025”, tape-measured depths on three different dates ..................................................... 15

Figure 4-8 – Heavy siltation in Angat River ....................................................................................................... 18

Figure 4-9 - Unregulated river profile with old town roads (white) .................................................................. 19

Figure 4-10 – Depths around Calumpit ............................................................................................................. 20

Figure 4-11 - Schematized cross section ........................................................................................................... 20

Figure 4-12 - Strong sedimentation at bifurcation in Calumpit (point “C17”) .................................................. 21

Figure 4-13 – Possible dike rings and primary defence system ........................................................................ 22

Figure 5-1: High elevation and buildings along Pampanga River ...................................................................... 25

Figure 5-2: Flooded areas (in blue) after design runoff event with peak discharge with return period of 5

years ................................................................................................................................................................. 26

Figure 5-3: Flood map Pampanga Delta after Typhoon Nari in 2013 with main streams and Calumpit ........... 27

Figure 5-4: Small dike in Pampanga Delta around fish ponds ........................................................................... 28

Figure 6-1: Locations of used rainfall stations in Pampanga River Basin .......................................................... 32

Figure 6-2: Gumbel distributions Zaragoza with k=1d (upper left), k=2d (upper right), k=5d (lower left) and

k=10d (lower right) ........................................................................................................................................... 35

Figure 6-3: Depth-Duration-Frequency curves for rainfall station Zaragoza ..................................................... 35

Figure 6-4: Intensity-Duration-Frequency curves for rainfall station Zaragoza ................................................. 36

Figure 6-5: Cumulative frequency curves rainfall station Zaragoza .................................................................. 37

Figure 6-6: Depth-Duration-Frequency curves for rainfall station Zaragoza ..................................................... 38

Figure 6-7: Intensity-Duration-Frequency curves for rainfall station Zaragoza ................................................. 38

Figure 6-8 - Water height gauges ..................................................................................................................... 40

Figure 7-1 - Predicted salt intrusion curve in the Pampanga River ................................................................... 43

Figure 7-2 - Tidal excursions (horizontal axis) and relative concentrations (vertical axis) in Hagonoy River .... 44

Figure 7-3 – Salt particle movement ................................................................................................................. 45

Figure 8-1: Legend of NDVI values in QGIS ....................................................................................................... 49

Figure 8-2: Land use map - NDVI, February 27, 1976 ....................................................................................... 50

Figure 8-3: Land use map - NDVI, January 25, 1989 ......................................................................................... 51

Figure 8-4: Land use map - NDVI, December 31, 2002 ..................................................................................... 52

Figure 8-5: Land use map - NDVI, May 27, 2013 .............................................................................................. 53

Figure 8-6: Locations of land use interviews including waypoint numbers ...................................................... 54

Figure 9-1: Typical treatment steps used for drinking water treatment in Hagonoy ........................................ 61

Figure 9-2: Proposed treatment scheme for treatment of infiltrated groundwater ......................................... 63

Figure 9-3: Resource oriented sanitation by splitting urine and faeces ............................................................ 64


Figure 10-1: Effects of the system – with pressures, thresholds, sensitivities and adaptabilities – on the

vulnerability ...................................................................................................................................................... 65

Figure 10-2: The dikes on the side of the Pampanga estuary ........................................................................... 68

Figure 10-3: The organisation of the Hagonoy MDRRMC as of September 2012. ............................................ 69

Figure 10-4: Evacuation centre in Calumpit in 2013. ........................................................................................ 70

Figure 13-1: Map of coastal municipalities in alliance ...................................................................................... 77

Figure 13-2: Flooding map Bulacan Province .................................................................................................... 79

Figure 13-3: Tide curves for reference stations ................................................................................................ 81

Figure 13-4: Tidal ranges obtained from diver measurements ......................................................................... 83

Figure 13-5: Tidal influence on depth measuring interval ................................................................................ 85

Figure 13-6: Measurements in Pampana mouth and Sulipan ........................................................................... 87

Figure 13-7: Depths Pampanga River ................................................................................................................ 89

Figure 13-8: Flow profile areas Pampanga River ............................................................................................... 89

Figure 13-9: Width variations Pampanga River ................................................................................................. 91

Figure 13-10: Depth measurements in Angat River .......................................................................................... 93

Figure 13-11: Depths Angat River ..................................................................................................................... 95

Figure 13-12: Flow profile areas Angat River .................................................................................................... 95

Figure 13-13: Depth measurements in Calumpit .............................................................................................. 97

Figure 13-14: Depths Pampanga (Calumpit) ..................................................................................................... 99

Figure 13-15: Depths Calumpit South ............................................................................................................... 99

Figure 13-16: Depths Calumpit North-East ....................................................................................................... 99

Figure 13-17: Depths Calumpit to Angat........................................................................................................... 99

Figure 13-18: Depths Angat (Calumpit) ............................................................................................................ 99

Figure 13-19: Depths Hagonoy River (B022) ................................................................................................... 101



Figure 13-22: Average depths River system .................................................................................................... 103

Figure 13-23: SOBEK 1D model on GIS layer ................................................................................................... 105

Figure 13-24: DEM Pampanga River Basin with 1D model in the Pampanga Delta ........................................ 106

Figure 13-25: Legend SOBEK 2D model (units: [m]) ........................................................................................ 106

Figure 13-26: IDF curves Sapang Buho ........................................................................................................... 107

Figure 13-27: IDF curves Zaragoza .................................................................................................................. 107

Figure 13-28: IDF curves Papaya ..................................................................................................................... 108

Figure 13-29: IDF curves San Isidro ................................................................................................................. 108

Figure 13-30: IDF curves Arayat ...................................................................................................................... 109

Figure 13-31: IDF curves Candaba .................................................................................................................. 109

Figure 13-32: IDF curves Sibul Spring .............................................................................................................. 110

Figure 13-33: IDF curves Sulipan ..................................................................................................................... 110

Figure 13-34: IDF curves Ipo Dam ................................................................................................................... 111

Figure 13-35: IDF curves San Rafael ................................................................................................................ 111

Figure 13 36: IDF curves San Rafael Fish ponds in project area (only for Pampanga River Basin).....................115


List of Tables Table 4-1 - Depth measurement locations ....................................................................................................... 14

Table 4-2 - Tidal wave characteristics ............................................................................................................... 16

Table 4-3 – Depth measurement accuracy – See Figure 4-5 for locations ........................................................ 17

Table 6-1: Percentages of days of no data records in rainfall stations.............................................................. 32

Table 6-2: Annual maximum daily, 2-day, 5-day and 10-day rainfall amounts for rainfall station Zaragoza ..... 33

Table 6-3: Rank, probability of (non-) exceedance, return period and reduced variate for rainfall station

Zaragoza for daily precipitation amounts ......................................................................................................... 34

Table 6-4: Values DDF curves rainfall station Zaragoza .................................................................................... 36

Table 6-5: Values IDF curves rainfall station Zaragoza ...................................................................................... 36

Table 6-6: Values DDF curves rainfall station Zaragoza .................................................................................... 38

Table 6-7: Values IDF curves rainfall station Zaragoza ...................................................................................... 39

Table 8-1: Land use details obtained at field interview locations ..................................................................... 56

Table 9-1: Global Health Impacts of Flooding based on Ahern et Al. (2005). .................................................. 57

Table 9-2: Ten Leading Causes of Morbidity in Bulacan Province (all ages) between 2004 and 2009

(rate/100,000persons). .................................................................................................................................... 58

Table 9-3: Diseases in the evacuation centres of Hagonoy on 16-8-2012. ....................................................... 58

Table 9-4: Vaccines of the vaccination program ............................................................................................... 59

Table 9-5: Measured concentrations of salinity, oxygen and pH in the tap water in Hagonoy......................... 60



Table of Contents

1 Introduction ..................................................................................................................................... 1

1.1 Problem description............................................................................................................................ 1

1.2 Research goal ...................................................................................................................................... 3

1.3 Scope of work ..................................................................................................................................... 3

2 Approach of Research ...................................................................................................................... 5

2.1 Introduction ........................................................................................................................................ 5

2.2 Fieldwork and associated data assessment ........................................................................................ 5

2.3 Assessment of available data .............................................................................................................. 5

2.4 Modelling ............................................................................................................................................ 6

2.5 Time Schedule ..................................................................................................................................... 6

3 Stakeholders .................................................................................................................................... 7

3.1 Formal stakeholders ........................................................................................................................... 7

3.2 Non-formal stakeholders .................................................................................................................... 8

4 River Profile Measurements .......................................................................................................... 11

4.1 Introduction ...................................................................................................................................... 11

4.2 Input Data – Depth Measurements .................................................................................................. 11

4.3 Measuring Methods .......................................................................................................................... 12

4.4 Locations ........................................................................................................................................... 14

4.5 Output – River Profiles ...................................................................................................................... 15

4.6 Reliability of measurements and their corrections ........................................................................... 17

4.7 Qualitative description of bottlenecks and guidelines ...................................................................... 18

4.8 Recommendations, future activities and use of data ....................................................................... 20

5 Hydrodynamic modelling ............................................................................................................... 23

5.1 Introduction software ....................................................................................................................... 23

5.2 Model components ........................................................................................................................... 23

5.3 Model results and discussion ............................................................................................................ 24

5.4 Preliminary validation ....................................................................................................................... 26

5.5 Conclusion ........................................................................................................................................ 27

5.6 Model improvement recommendations ........................................................................................... 27

6 Advanced Model Input .................................................................................................................. 31

6.1 Rainfall analysis ................................................................................................................................. 31

6.2 River Runoff ...................................................................................................................................... 39


7 Salt Intrusion .................................................................................................................................. 41

7.1 Introduction ...................................................................................................................................... 41

7.2 Parameters ....................................................................................................................................... 41

7.3 Tidal dynamics .................................................................................................................................. 42

7.4 Intrusion curve .................................................................................................................................. 43

7.5 Salt measurements in Hagonoy ........................................................................................................ 44

7.6 Recommendations ............................................................................................................................ 45

8 Land Use Changes .......................................................................................................................... 47

8.1 Problem description.......................................................................................................................... 47

8.2 Introduction research plan ............................................................................................................... 47

8.3 Data availability, preconditions and constraints ............................................................................... 48

8.4 Data processing ................................................................................................................................ 49

8.5 Results .............................................................................................................................................. 50

8.6 Validation of land use ....................................................................................................................... 54

9 Flood Resilient Sanitation .............................................................................................................. 57

9.1 Current situation ............................................................................................................................... 57

9.2 Improving the sanitary conditions .................................................................................................... 62

10 The Framework for Vulnerability ................................................................................................... 65

10.1 What is vulnerability? ....................................................................................................................... 65

10.2 Theory of the vulnerability framework ............................................................................................. 66

10.3 Capacities in the Manila Bay Delta .................................................................................................... 67

10.4 Conclusions and recommendations .................................................................................................. 71

11 Conclusion ..................................................................................................................................... 73

12 References ..................................................................................................................................... 75

13 Appendices .................................................................................................................................... 77

Manila Bay Delta Challenge MAIN REPORT – MARCH 2014 1

1 Introduction

1.1 Problem description

1.1.1 Background

The Philippines is a country in South East Asia, consisting of thousands of islands and being encircled by the

beautiful, yet often notorious Pacific. As subject to diverse natural influences, it had to suffer incessant

welfare catastrophes through history. Many of these occurrences involved water related problems,

whether in form of abundance or scarcity.

1.1.2 Nature and extent of the problem

The main problems which relate to water and disaster management and which cause socio-economic

disruptions in the Pampanga Delta are tidal and fluvial floods around the rivers Pampanga and Angat. Major

low-lying areas are frequently inundated because of combinations of numerous aspects.

1.1.3 Problem cause

The water related problems have several causes. Many are - directly or indirectly - the result of floods,

which are generally caused by two phenomena. Firstly, one can mention the flooding related to the

periodic tidal incursion, where the water comes from the river mouths. Secondly, one can relate the floods

to heavy rain events, leading to high discharge peaks and extreme water levels. In the latter case the water

comes from upstream and takes place less often than flooding due to the periodic tidal incursion, but its

effects could be more dramatic. In addition, the country regularly deals with high storm surges of typhoons

coming from the Pacific Ocean. The combinations of these three phenomena are causing problems to a

much larger extent.

The flooding problem is not new for the area. Since olden times there are problems in this delta from these

two major rivers. The upstream drainage system has dramatically changed due to land development for

agricultural use and human settlement resulting in short flood concentration times, higher peak discharges

and reduced flood carrying capacity of rivers because of considerable siltation. Another thing that has

contributed to the worsening of the river conditions is the discharge of volcanic substances to Manila Bay

due to the relatively recent eruption of Mount Pinatubo in the year 1991.

1.1.4 Climate conditions

In the Philippines a tropical and maritime climate prevails. Generally, temperatures are high, just like the

humidity and the amount of rainfall averaged over the year. However, rainfall is not equally split over the

year. From June to November it is rainy season, bringing most of the annual rainfall. From December to

May it is dry season. This dry season could be subdivided in a (relatively) cool dry season from December

till February and a hot dry season from March until May. Thus, it can be stated that extreme pluvial

flooding is bound to seasonal conditions.

1.1.5 What has been done already?

No definitive solutions against this influencing factor are implemented yet. Only temporal measures are

applied and continuously adapted according to the demands of the population, which is convicted to

almost individual, small-scale, self-sufficient based solutions. Examples of such measures are self-made

dikes and newly elevated roads. It may be clear that measures like these do not solve the problem, but

rather shift it.


There are already some final solutions from previous proposals implemented to prevent upstream flooding

in the area. In 1989, the Pampanga River Flood Control System was implemented. The construction of two

dikes which is the first phase of the Pampanga Delta Development Project was a big step in protecting the

Pampanga Delta from upstream floods. However, due to budget constraints and disagreements from

several households only 14.2 [km] (right bank) and 13.2 [km] (left bank) from the intended 22.7 [km] were

built. It improved the situation regarding flooding at certain locations (mainly close to the location of the

dike). However, this final solution did not have any positive effect on most of the people in the entire area.

Fact is that the flood control system remains incomplete and that the area is still vulnerable to upstream

floods1.

1.1.6 Action

In the year 2009, an alliance with eight neighbouring coastal municipalities (see Figure 1-1 and [13]) north

of Manila Bay (Luzon Island) was implemented. The goal of the alliance was to find out how the

representatives of these areas could collaborate on developing plans in order to prevent floods and fight

water pollution in their municipalities. The scope of this alliance is thus on water management and disaster

management for a better welfare and wellbeing in the eight municipalities. This multidisciplinary and

integrated water management approached research on the flood prone areas in the Pampanga Delta is the

first result of this alliance.

Figure 1-1 - Project location (Map data: Google, 2014)

To solve the problems related to flooding due to the two mentioned types of flooding, new physical system

construction works are inevitable to keep this area a suitable place to live. Before one can design a new

system of physical constructions, more insight in the direct and indirect water related problems and system

properties in this area are necessary.

1 Philippine Statistics Authority – National Statistical Coordination Board; (June, 2013)


1.2 Research goal

Design of a new system of physical constructions is inevitable to keep this delta a suitable place to live by

preserving it as a legacy for the next generations of the eight municipalities. New physical solutions - like

hydraulic structures - can only be designed if the system properties are known and water related problems

are assessed in a quantitative way. An extensive virtual reality model taking into account all the system

properties, boundary conditions and vulnerable areas is necessary before statements can be made about

the design of new protective interventions. The aim of this multidisciplinary project is to quantify the direct

and indirect water related problems, system properties, boundary conditions and vulnerability of areas in

the eight coastal municipalities from the alliance and visualize it with a start-up delta simulation. The result

is a guideline for the proposal of possible physical solutions in this coastal region.

1.3 Scope of work

Initially, the goal of the project was to research the water related problems in all eight coastal

municipalities. Due to the tight time schedule and considerable financial restrictions, it was not possible to

do the same study for all eight municipalities. The spatial scope of this research is therefore mainly focused

on the municipalities of Hagonoy, Paombong and Calumpit, and (less in detail) also on Obando, Bulacan,

Malolos, Macabebe and Masantol. The detailed research principles would be exactly the same for the latter

regions.

The substantive scope of the project is mainly focused at the specializations of the four group members.

The topics that are discussed in this report will deal with hydrology, water resources management, overall

hydraulic engineering and sanitary engineering. Topics in these research fields will be discussed and

interrelated in the report.

The temporal scope of this research is focused on two timescales. On one side the focus is on the time

range in which the measurements are performed. These findings say something about the state of the

system at that time. On the other side, interviews were performed and historical measurements were

requested which focus on a larger timescale, namely that for which memories of the oldest interviewed

people still exist and a timescale for which historical data is still available. These two longer time scales

seem to match. For both data is available from the 1970s.

One has to take into account that this research is part of a more extensive research with the aim of solving

the flood related problems in the delta of the Pampanga catchment and surroundings. This research will

not come up with final designs, however some (temporal) solutions are proposed for several consequences

of the flooding problem. This report is moreover presented as a guideline for solving the inconvenient

flooding problem and its omnifarious aftermaths.



2 Approach of Research

2.1 Introduction This chapter describes the research approach, which used as a guided the team through the project. The

research can generally be split up in three different phases, all essential in order to obtain adequate

results. In each research phase the materials and methods are briefly explained. Afterwards, a time

schedule of the research is given.

2.2 Fieldwork and associated data assessment The fieldwork for this research took place in the study area for a period lasting from November 25, 2013

until January 20, 2014. In this time, the project group was based in the municipalities of Malolos and

Hagonoy, which are located in the project region. In this research step the project group was totally

dependent on the brought materials and resources available in the Philippines.

2.2.1 Water quality measurements

Water quality measurements are performed for a broad spectrum of topics in this research. Conductivity

and temperature measurements are done in the Hagonoy River and at several other locations in order to

make statements about salt intrusion in the Pampanga Delta. Furthermore, these measurements – along

with O2 and pH tests – are done for potential drinking water quality analysis and statements about flood

resilient sanitation in the project area.

2.2.2 Water depth measurements

River profile measurements are done in order to make statements about the quantitative properties of the

Pampanga Delta main drainage system. These highly detailed cross section overviews of main rivers give us

the opportunity to analyze the exact flow profiles over the whole river length. The obtained data is also

used as preliminary model input and could also be used for more advanced models. Depth measurements

for relatively small rivers are performed from local bridges with weighted measuring tapes, while larger

rivers are measured by a sonar device designed for measurements from the water surface. A local boat is

used for maneuvering on the water. Furthermore, logging divers are placed on several fixed locations in the

Pampanga Delta to determine the tidal behavior, which is used for water depth corrections due to tidal

influences from Manila Bay. For all the depth measurements, a GPS device is used for marking of the exact

location and measurement time.

2.2.3 Interviews

Field interviews form an essential part of the research. Problems are best indicated by asking people

directly about their experiences with a relevant topic. Houses spread over the project area are visited to

interview their inhabitants about their experiences with floods and associated sanitary conditions. Besides

this, farmers and people living on the countryside are asked about their experiences with land use and

eventual land use change due to floods and salt intrusion in the area. Furthermore, the former mayor of

the municipality of Hagonoy is interviewed about his views on the problems in the project area. The

stakeholder analysis is partly based on the results of field interviews.

2.3 Assessment of available data

During the time in the Philippines, data from several local institutes is obtained to use in diverse analyses.

Furthermore, data from online databases and results of previous reports and other literature are used in

the overall investigation. This research phase started in September 2013 and lasted until March 2014.


2.3.1 Data acquisition from local institutes and analysis

Information from local institutes is incorporated in the research to get specific data – measured by local

specialists – about the effects of flood susceptibility on sanitation. Furthermore, rainfall data and rainfall-

runoff relations, useful for hydrological analysis, are obtained from local institutes. GIS data (shape files) is

also obtained from local institutes and the internet. These files are used in this report.

2.3.2 Data acquisition from online databases and analysis

Data from online databases is used for optical visualization of the effects of the flooding problem in time.

By using free satellite data, land use change patterns in this delta are investigated. Satellite data is also

used for preliminary hydrodynamic modelling and its output validation. Online elevation maps form

essential 2D input in the model.

2.3.3 Data analysis from previous reports and other literature

Nearly all research steps required input from available (scientific) literature and previous reports. See the

reference list for all used literature sources and reports.

2.4 Modelling

One of the last parts performed in this research is the hydrodynamic modelling, which is essential for

visualizing and eventually solving of the flooding problem in the near future. After sufficient data analysis is

done and enough measurements are performed to create model input, a preliminary hydrodynamic model

is made and validated with flood maps of the project area. The modelling software package SOBEK is used

for this research phase, which took place at the end of March, 2014.

2.5 Time Schedule

The time span of this research is shown in Figure 2-1. Since the three research phases show a lot of overlap

and do not exactly match every research topic, a more general time schedule of research steps is shown,

including the time planned for elaborating.

Figure 2-1: Time span of research

Sep-13 Oct-13 Nov-13 Dec-13 Jan-14 Feb-14 Mar-14 Apr-14

Pre-research phase

Fieldwork phase

Data analysis phase

Modeling phase

Reporting phase

Date (Month-Year)

Pro

ject

Ph

ase

s

Time span of research


3 Stakeholders

This chapter gives a quick overview of the stakeholders, which have to be taken into account for this

multidisciplinary research. One can split the subject in formal and non-formal stakeholders. The analysis is

mainly based on information from literature and interviews conducted in the field.

3.1 Formal stakeholders

Formal stakeholders are stakeholders with a certain formal position in the political system of a country.

They are part of several administrative regions from the Philippines and they have responsibilities. Before

the governmental stakeholders and their responsibilities are described in more detail, the political system

in the Philippines will be shortly explained to clarify the relations between different stakeholders and to

give a clear overview.

2 3 The Philippines is divided in seventeen regions. Most of these regions do not possess a separate local

government. This means that they do not have political power and that mainly an administrative function

can be fulfilled. The name of the region of this project area is Central Luzon. Regions are generally divided

into provinces or in cities independent from a province. The project area lies in two provinces, Pampanga

and Bulacan, which are governed by a governor and a council. A province consists of several municipalities

or component cities. Two of the municipalities of the project area are located in the Pampanga province

and six in Bulacan province. The municipality is governed by a mayor and a council. The mayor could be

elected for a three-year period and cannot be elected for more than three successive terms. The smallest

administrative division in the Philippines is the barangay. Barangays are governed by a head with a

barangay council. An overview of the municipalities in the project area is given in [13].

3.1.1 Pampanga River Basin Flood Forecasting Warning Center (PRFFWC or PRBFFWC)

This is an office center of the Philippine Atmospheric, Geophysical & Astronomical Services Administration

(PAGASA) of the Department of Science & Technology (DOST). Their task is to monitor the hydrological

situation, forecast and provide flood warnings to the flood prone areas within the Pampanga and Guagua

river basin systems. Their focus is on flooding events due to overflowing of rivers. They also maintain and

operate several rainfall and river gauging stations in the two river basin systems.

3.1.2 Bulacan Provincial Disaster Risk Reduction and Management Council (PDRRMC)

This PDRRMC, which is an office in the Provincial Government of Bulacan and is guided by PRFFWC,

maintains and operates a network of rainfall, river and flood stage observation stations within the province

of Bulacan as part of its flood disaster mitigation and management program (CBFMMP). In this program,

data is communicated on a local scale between monitoring stations of hydrological parameters, municipal/

barangay disaster action teams and the operations center (Provincial Capitol and PRFFWC).

3.1.3 The alliance of eight coastal municipalities:

All the eight municipalities (Macabebe and Masantol (Pampanga); Bulacan, Calumpit, Hagonoy, Malolos,

Obando and Paombong (Bulacan)) in this alliance have their own disaster council responsible for their own

municipality or there are more disaster councils per municipality, the so called barangay disaster councils.

Every municipality has its own coping plans during floods, because they have many experience how to deal

with disasters. The mayors of the municipalities are formally responsible during floods, however the main

2 PRFFWC (2013)

3 National Statistical Coordination Board; (June, 2013)


work is done by municipal engineers or planners. The municipalities mainly see coping with floods as their

task. Protecting the area and recovering the area after a flood is not considered as their task, because they

do not have money for area recovery and short political time span makes it difficult to implement area

protecting plans.

The alliance of eight coastal municipalities is established to make the issue of flood prevention and water

pollution a common issue, to avoid the problem of implementing protection plans because of the political

situation that changes every year. The municipal engineers and planners are involved in the alliance. Mr.

Cruz, former mayor of Hagonoy, is the initiator of this alliance.

3.1.4 Water companies

Water companies are responsible for the water supply. They supply water mainly within the municipal

borders. The water supply is highly dependent on the water quality and quantity. Therefore, the water

companies also focus on the sanitation and wastewater disposal.

3.2 Non-formal stakeholders

Non-formal stakeholders are stakeholders without formal political influence and responsibilities in the

political system of a country. This does not mean than the lack of formal political influence automatically

indicates that these stakeholders have no influence at all. Non-formal stakeholders can influence a process

in a positive or negative way, and varies according to their relative power and interest.

3.2.1 Farmers

Farmers are mainly located in the northern areas of the eight municipalities. In this area the water used for

irrigation has a relatively low salinity to allow agriculture. The main crop cultivated in this area is rice, which

is relatively labour-intensive to grow. Rice farmers are often small land owners or they are tenants of larger

land owners who rent to land to more rice farmers.

Rice farming often deals with problems here. Frequent river floods often destroy crop yields meaning that

the income of the rice farmer fluctuates due to this. Another problem is that the harvests of rice fields

often decrease due to increase of salinity in irrigation water over the years. Yields often get so low that

growing rice is not economical any more. Because of this, rice fields disappear and labourers on the

paddies can become unemployed.

3.2.2 Fishermen

In the south of the coastal municipalities, most of the fishermen are living. Sometimes they live on small

islands close to Manila Bay, sometimes they live on the mainland close to the rivers. They often go out on

Manila Bay to catch fish or visit their traps to empty them. Other important fishing grounds for these

fishermen are Pampanga River, Labangan Channel and Hagonoy San Juan River.

The yields are often dried and prepared for sale in the barangays of the fishermen. The fish are generally

used for own consumption, sold on local markets or prepared for export out of the municipalities of the

fishermen. Floods can influence the income of the fishermen because they can’t go out on the water

during the flood and sometimes fishing material like nets and traps are destroyed during these events.

3.2.3 Fish pond owners

Another group of stakeholders responsible for fish yields are the fish pond owners. Mainly in the south of

the coastal municipalities, large areas are filled with (embanked) fish ponds. Small dikes or nets around

open water areas create fish ponds where fish is grown. Types of fish grown in these fish ponds are for


example: milk fish (bangus), tilapia, prawns and crabs. Large areas of fish ponds are sometimes generally

owned by a few land owners, making these fish pond owners quite influential stakeholders.

Problems occur during floods if the embankments are overtopped by the water so the fish could swim

away or if the nets around the fish ponds are destroyed. Another problem related to the fish pond owners

is the water pollution because of the feeding of the fish. Rice paddies that are not economical any more are

often converted to fish ponds, increasing the proportion of fish ponds in the region and thus the presence

of this group of stakeholders over the years.

3.2.4 Other Inhabitants

Next to farmers and fishermen, one has to take into account the importance of other inhabitants in the

area. Problems regarding to flooding are often related to inundation of houses and other personal

belongings. There is a great variety in life standard in this area, with a striking fact that the more developed

households are located in the north of the area, relatively far from Manila Bay. If one takes a look at the

professions of these people it is clear that many people do work on the rice paddies or do work as tricycle

driver. People working on rice paddies sometimes get unemployed because of the fact that the yields of

the rice paddies decreases leading to a decrease in employment.

3.2.5 Industry and other commerce

(Rice) agriculture and fish trade are the main economic forces in the eight municipalities, however there is

also other industry and commerce present in the area. Especially in the north of the area (around Malolos)

there is some industry and there are also larger shopping areas here. In the south (around Paombong and

Hagonoy), small barangay shops are more common.



4 River Profile Measurements

4.1 Introduction Due to the frequent water flow towards the cities, the population of the Pampanga Delta takes action in

order to protect their families, belongings and land. The almost yearly occurring phenomena of extreme

river discharges combined with tidal influence and a strong storm surge in Manila Bay cause social

catastrophes and disrupt a huge part of the already instable economic system. In addition, the downstream

areas are even highly susceptible to the stand-alone monthly tidal influence, which standardly causes a

considerable amount of flood days per month.

The problem is flooding, although it could rather be seen as a logical natural consequence of not

maintaining the delta. The real complexity lies inside the fact that there is little understanding of the flow

systems and that the local experts do not have the required equipment to investigate the exact nature of

the problem.

If this would only be a political issue, the population would have already taken matters into their own

hands. What the people need is a revolutionary water management approach in order to cope with the

flooding in the delta. This does not mean holding the water outside of the populated area, for this is almost

impossible in this case. It means living with the water. Therefore detailed technical data is required.

Based on studies and various reports, it can be concluded that the channel and river discharge capacities

are far below required. The part upstream of Masantol can hardly cope with a five year return period of

upstream flooding4. Changes in land use cause disruptions in the channel system and therefore changes in

riverine sediment balances. There is a clear difference in river depths upstream and downstream of the

side channels, likely due to these adaptations. The Angat and the Pampanga, as well as the smaller rivers,

are full of unmaintained profiles and not navigable during some periods.

Relocation of inhabitants or making room for the river in vertical direction may be the only possible

solutions. The latter solution has to be elaborated in order to increase the discharge capacity, because the

first option seems radical and expensive. Some may even designate relocation as something ethically

inappropriate and disrespectful towards their predecessors - therefore unacceptable -.

4.2 Input Data – Depth Measurements

The choice for depth measurements in and around the Pampanga and Angat can be explained by the high

significance of system understanding in the delta. A description of the whole channel system can make us

visualize the flowing pattern now and possible scenarios in the future with 1D/2D models (e.g. SOBEK5).

Eventually, this can give the possibility to gradually look for solutions, based on existing adaptation

measures and civil structures all over the world. Looking at the flood maps a conclusion can be made of

which river profiles maintain a sufficient and safe discharge for the inhabitants to keep dry feet, and which

sections have to be adapted. Therefore quantitative and qualitative descriptions are essential in this

solution process, in order to define the bottlenecks that cause large river morphological disruptions.

4 Japan International Cooperation Agency (2011)

5 Deltares (2013)


4.3 Measuring Methods

The cross sections of the rivers/canals (see Figure 4-1) are measured by boat with sonar (see Figure 4-2) or

from bridges with a tape-measure (see Figure 4-3). In the larger rivers it was inevitable to use a boat for the

bank-to-bank measurements. Because of the lateral flow and the boat movements, these measurements

are corrected later on and a straight line is assumed. At the mouth of the Pampanga River and further

upstream at Sulipan divers (see Figure 4-4) are placed for approximately two weeks to measure pressure

variations at the two locations. These pressure differences, which are translated to water heights, are used

to correct for absolute depth measurements.

Figure 4-1 - Measuring river profiles 6(Images/maps: Google, DigitalGlobe, Europa Technologies, 2014)

Figure 4-2 - Depth measuring sonar with GPS

6 Google Earth


Figure 4-3 – Lorrie and Ante determine the approximate flow profile with tape-measure-weight

The plan was also to get tidal data from a diver at the Angat River mouth, but unfortunately the device

went missing. Without measuring the tidal influence, an approximation of the depth variation can still be

made, looking at the tidal wave in the Pampanga. The wave will pass the Angat mouth first and by

approximating the wave celerity, some new assumptions can be made of what can happen further

upstream. Due to the significant uncertainty of these assumptions, the tidal influence in the Angat-

Labangan has not been elaborated further on. The same counts for the rather complex system around

Calumpit.

Figure 4-4 - Diver 7

7 Alliance for coastal technologies (2013)


4.4 Locations

The profiles of the main river courses which are responsible for the largest discharges have to be defined.

These measurement locations are indicated in Figure 4-5 and Table 4-3. Locations “S30” (Pampanga) and

“A28” (Angat) are the last points in the series, respectively because of enough data and navigational

restrictions. In the rivers Hagonoy and Paombong the improvising method is used in order to approximate

the depths of the branches. Again, sub-branches of the two latter rivers can be assumed to have somewhat

lower water levels. These primarily use as storage, though it can have significant importance in the overall

sediment balance of this delta. The choice not to measure these is primarily due to the lack of time and

financial means.

Figure 4-5 - Diver and depth measuring locations8(Images/maps: Google, Terrametrics, 2014)

Table 4-1 - Depth measurement locations (see Figure 4-5)

River/Channel Locational abbreviation

Pampanga S

Pampanga west-branch W

Angat/Labangan A

Calumpit C

Hagonoy 022;023;025

Paombong (Not indicated on map)

8 Google Earth


4.5 Output – River Profiles

4.5.1 Assumptions

Some assumptions have been made for the reality check and further development of potential models.

- Tide: M2+S2 → diver measurements (see [Appendix 4 ]) and checked with previously available data (see [Appendix 3 ]);

- Discharge: ≈ 250 [m3/s] → calculated and checked with yearly average discharge9; - Banks heights: Hagonoy, Paombong and Calumpit 0.5-1.5 [m]; Pampanga and Angat 2-4 [m].

4.5.2 Technical elaboration

The collected data has been corrected and visualized in Excel (see Figure 4-6 and Figure 4-7) and is

available on request. Here, it was very important to correct the absolute depths for the tide in order to get

the absolute maximum and minimum values at the two diver measuring points. Everything in between can

be corrected (see [Appendix 5 ]). In [Appendix 6 ] different elements of the profiles, such as maximum

depths, average depths, cross sections and width variations are elaborated.

Figure 4-6 - Example: sonar depth measurements of point “S01” (Pampanga mouth)

Figure 4-7 - Bridge “025”, tape-measured depths on three different dates

9 Japan International Cooperation Agency (2011)


4.5.3 Correction for tidal influences

In the points below, the depth correction for two locations is explained at a certain stable discharge for a

14-day measuring period.

- Sulipan:

Absolute range ≈ 0.2 – 1.45 [m] → range = 1.25 [m]

Depth with depth measuring device on T: - 9.4 [m] ~ 0.777 [m] with diver

Maximum depth: 1.45-0.777=0.673 → 0.673+9.4=10.073 [m]

Minimum depth: 0.777-0.2=0.577 → 9.4-0.577=8.823=8.82 [m] - Pampanga mouth:

Absolute range ≈ -0.2 – 1.05 [m] → range = 1.25 [m]

Depth with depth measuring device on T: - 5.9 [m] ~ 0.2 [m] with diver

Maximum depth: 1.05-0.2=0.85 → 0.85+5.9=6.75 [m]

Minimum depth: 0.2-(-0.2)=0.4 → 5.9-0.4=5.5 [m] The tidal influences based on diver measurements indicate that in both points there is an approximate tidal

range of 1.25 [m]. This tidal range comes as a result of the amplification of a semi-diurnal tidal

characteristic (M2+S2) and comes once in every two weeks.

4.5.4 Average river depth

According to the divers the travel time of the tidal wave is approximately one hour and four minutes of the

passing wave tops, measured from the mouth of the Pampanga to Sulipan. The distance is approximately

24 [km], so the wave travels with 24/1.066=22.5 [km/h]=6.25 [m/s]. With c=√(gh), this wave celerity gives

an approximate average river/canal height of 4.0 [m]. With [Appendix 7 ], which gives an indicative and

approximate average depth of 4.3 [m] (uncorrected depth, after the tidal wave), the “average depth” of

the measured path can be represented relatively accurate by a value of 4.0 [m] (see Table 4-2).

Table 4-2 - Tidal wave characteristics

Characteristics Value Unit

Time difference for tidal wave tops: 1.07 [h]

Distance divers: 24 [km]

Wave celerity: 22.5 [km/h]

Wave celerity: 6.25 [m/s]

Average depth: 3.98 [m]

4.5.5 River width variation

Based on the predominantly exponential width variation of the river (see [0]), it can be stated that in

average the Pampanga has a convergence length of approximately 50-60 [km].


4.6 Reliability of measurements and their corrections

4.6.1 Sonar

The sonar accuracy lies in a range of a couple of centimetres, so in most cases this is at least 95%.

4.6.2 Tape-measure

The choice for the tape-measure was an improvisational method, during the important salinity

measurements from bridges. It primarily gave an insight of the approximate river/channel depths of the

main branches. As can be seen in [Appendix 13 ], the depths vary between 1.0 and 2.25 [m].

4.6.3 Width measurements

The width measurements are performed with “Google Earth”. Here, an accuracy of 90-95% is assumed,

which is close enough to qualitatively describe the character of the width variation further upstream.

4.6.4 Technical reliability check

When including the tidal influence, the average depths do not change a lot. The fluctuation of these is 0.2

[m] at max. (see [Appendix 7 ]), as measured during this time interval at the assumed approximate

discharge. The tidal influence, in form of a maximum fluctuation, was predominantly unamplified semi-

diurnal and it did not rise above a 0.4 [m] difference during the measuring interval. Based on the fact that

the measuring device has a relatively low inaccuracy, it can be stated that the average depth

measurements have a reliability of at least 89%. The reliability of the maximum depths is approximately

98% (see Excel-file of depth measurements).

The measurements in the Pampanga were taken during one of the lowest water levels and it can be

concluded that the depths close to the mouth are expected to be higher by 1.0 [m], because they were

measured just before the tidal wave came in. This can also be seen in the corrected values of depth

measurements in the Pampanga River mouth and the Angat.

Checking with backwater curves is too limited here, because of variations in profile, roughness and slope,

although a reasonable assumption has been made for the average discharge of the Pampanga in the

measuring period. This has been calculated ≈ 250 [m3/s] and compared to other available data10, assuming

a 4.0 [m] “average depth” (see [Appendix 7 ]).

River/Channel Abbreviation Measurement type Accuracy

Pampanga S Sonar High

Pampanga west-branch W Sonar High

Angat/Labangan A Sonar High

Calumpit C Sonar Average to High

Hagonoy 022;023;025 Tape-measure-weight (+sonar) Low to Average

Paombong (Not indicated) Tape-measure-weight Low

Table 4-3 – Depth measurement accuracy – See Figure 4-5 for locations

10

Japan International Cooperation Agency (2011)


4.7 Qualitative description of bottlenecks and guidelines

Besides the low-lying poorly protected areas and the numerous available areal descriptions, alongside with

hazard maps, there are still visibly notable obstacles in the rivers. Fish ponds and even complete

neighbourhoods develop on the banks of the rivers, where one sees siltation as a new housing opportunity.

Little do these citizens probably know, that this is one of the main reasons of upstream flooding: the river

has no room.

4.7.1 Plaridel, Pulilan and Malolos

The river Angat is an infamous example of this fact. Looking at the depths and areas further upstream (see

[0] the wet cross sections decrease dramatically and almost linearly, to even less than the half cross section

of the Pampanga. Although having a much lower discharge than the Pampanga, in case of a new bypass

this would be a new bottleneck. Further upstream at point “A28” (see Figure 4-5), with coordinates

[120.855785°, 14.892654°], the water level was too low even to navigate. Also based on “Google Earth”,

the careful yet very realistic conclusion can be drawn here that there is heavy siltation further upstream of

Plaridel (see Figure 4-8) and that room has to be made for the river, vertically (by dredging) and – if

possible – also horizontally (by removing obstacles).

Figure 4-8 – Heavy siltation in Angat River (Images/maps: Google, 2013, DigitalGlobe, 2014)


4.7.2 Hagonoy and Paombong

Also remarkable are the densely populated inner bends, in this case in Hagonoy. It seems that the main

road has been built alongside the Hagonoy River centuries ago. As it continued meandering around the

city, erosion of the outer bend and sedimentation of the inner bend took place as a result of the secondary

flows. The deposits in the inner bend turned out to be an opportunity for the inhabitants, for building more

and more towards the river. Also, the outer bend has to erode and the houses there disappear or continue

to be built on piles. Most of the time, the latter is the case. The result is that the river loses its natural flow

profile and during high river discharge, the floods become more severe at these narrow places (see Figure

4-9).

Figure 4-9 - Unregulated river profile with old town roads (white) (Images/maps: Google, DigitalGlobe, EuropaTechnologies, 2014)

Due to strong tidal influence and the mentioned flood combinations it seems highly improbable that these

cities will deal soon with the monthly occurring tidal floods. Unregulated groundwater extraction makes

the ground level decline, which makes the tidal floods deeper and more severe. The expectations are that

this will worsen 11 12.

Some would say that the citizens are forced to move, but there is no concrete proof that they already

started relocating. Besides, in most cases the relatively poor population has no other place to go. Structural

governmental policy on relocation and social housing, potentially supported by international funds could

be an option in the near future. However, in order to keep these cities alive, concrete structural plans have

to be proposed to offer a physical solution in form of a primary defence system, regulated with sluices and

combined with a fully risk-based backup dike ring system against fluvial flooding (see Figure 4-13). One of

the results of this is that the rivers are canalized and that the land use will change significantly.

11

Feasibility Report on the Pampanga Delta Development Project, Main Text, February 1982 12



4.7.3 Calumpit and the main Pampanga-Angat connection

The average channel depth around Calumpit is approximately 1.7 [m] (see Figure 4-10). This is considerably

lower than the average water level in the Pampanga, but because this is not the main discharge channel,

the value for the depths is considered to be a relatively correct assumption of average measurements. Still,

this city has to deal with tidal and upstream flooding. Dredging for a sufficient discharge and storage seems

inevitable. Furthermore, a similar dike ring system as suggested for Hagonoy and Paombong could be

placed.

The connection channel between the rivers Angat and Pampanga is around 3.3 [m] deep and a factor 1.5 [-]

wider than the channel around Calumpit. This also seems not enough for a sufficient discharge, because on

the flooding map (see [Appendix 2 ]) whole areas around Calumpit and even to the south of the connection

channel are flooded.

Unfortunately, this image is not publicly available. For more information on these

data, please send an email to [email protected]

Figure 4-10 – Depths around Calumpit13

(Images/maps: Google, Aerometrex, Cnes/Spot Image, DigitalGlobe, Landsat, 2014)

4.8 Recommendations, future activities and use of data It is clear that the channels cannot cope with some extreme scenarios and that the areas have to be

protected. The modelling of these channels has to be done with a highly detailed Digital Elevation Model

(DEM), because small changes in this area can have large consequences on the flood model. This map has

to be imported in a programme like SOBEK 1D/2D if we want to predict the flow patterns. Therefore

sections of certain river ranges have to be modelled like Figure 4-11. Small adaptations to channel depths

and dikes/dike rings can already lead to the desired effect of a considerably reduced flood risk.

Figure 4-11 - Schematized cross section

With this approach, the clear obstacles like in Figure 4-12 can be removed in order to give more room to

the river for a safe discharge and possibilities for transport over water. New economic opportunities can be

created this way.

13

QGIS (2014)


Figure 4-12 - Strong sedimentation at bifurcation in Calumpit (point “C17”)


Figure 4-13 – Possible dike rings and primary defence system14

(Images/maps: Google, TerraMetrics, 2014)

Eventually the required river or channel depths for the given discharges can be maintained or made.

Furthermore, the cities and villages have to be protected against flooding, for it is inevitable for the people

to leave these areas if nothing is done in the surrounding areas. Good education on environmental

sustainability, a highly maintained environmental policy and a high protection level of the areas can make

these cities new economic centres of the delta and most probably teaching material for other regions in

the Philippines or other countries with similar problems. If the recommendations are carefully technically

elaborated, this delta has the opportunity to grow out to a tropical reflection of the Netherlands.

14

QGIS (2014)


5 Hydrodynamic modelling

This chapter will give a first overview of a hydraulic model, created for the Pampanga Delta. The purpose of

this model is to give a first impression of the effects of high river discharges in the Pampanga River Basin.

After a short introduction of the hydrodynamic modelling software used for this model, SOBEK 1D2D, the

model components and the model itself will be described. Some preliminary results are shown and

compared with flooding areas, which are obtained from remotely sensed images. Since this model will be a

preliminary indication, the results should not be taken for granted. This model is meant to give the reader a

first overview of computer model possibilities and shows the importance of proper data for hydrodynamic

modelling. After the results, discussions and a conclusion follow in order to answer the following question:

Why is better physical data essential for this area?

5.1 Introduction software

The modelling software used in this research is called SOBEK. This software, created by the company

Deltares from the Netherlands, is a powerful modelling tool for flood forecasting, optimization of drainage

systems and many other hydraulic matters15. The software makes it possible to calculate water flows in a

one-dimensional (1D) network and in a two-dimensional (2D) grid. The model is based on the Saint-Venant

Equations. This way, the software can calculate water levels, discharges and water storage in 1D channels,

as well as flow and water levels on 2D grids. Both, the 1D and 2D flow module are used for modelling, since

water movements are not limited to the rivers and channels only, but are also used for large inundated

land areas.

5.2 Model components

Before a model of an area can be made, data of dimensions of the region is required. Data used in this

model is obtained in several ways. It was delivered by external organizations like PRFFWC and USGS as well

as from our own measurements in the larger rivers. This section gives an overview of the different data

used in the model for the 1D component as well as the 2D component and their boundary conditions.

Meteorological data in the area of interest is neglected, for the reason that this is only a preliminary model

and also because the discharge coming from upstream from the entire Pampanga River Basin is expected

to have a higher influence on the flooding of the area.

5.2.1 Physical data for 1D flow module

For horizontal dimensions, a GIS-layer (shape file) is used, imported as a background layer in the SOBEK

schematization editor. On this GIS-layer (obtained from PRFFWC)16, all the mayor drainage components are

represented. The model outlines of the main river branches are marked on top of this layer to create the

1D system of the area. Only the main drainage system in the Pampanga Delta is sketched, both for

simplicity reasons and because of the fact that a good overview of the model behaviour of these rivers

gives enough insight in the behaviour of the water system for this first flow impression. It is chosen to

create calculation points in the model after every two kilometres. After this part is finished, dimensions will

be given to the several river branches. The dimensions are obtained from own measurements. However,

these are considerably simplified for this first modelling attempt. Since the slope of the Pampanga River is

smaller than 1:10,000 in the first 20 [km] and between 1:10,000 and 1:5,000 after 20 [km] until 70 [km]17, it

15

Deltares (2013) 16

PRFFWC (2013) 17



is estimated that the difference in elevation of the river bed between the upstream and downstream

boundary conditions is around 3 [m]. An overview of the drainage system for this model is shown in

[Appendix 15 ].

5.2.2 Physical data 2D flow module

For the 2D flow module, a Digital Elevation Model (DEM) obtained from USGS18 will be used. Initially, it was

desirable to use data from SRTM 19 (Shuttle Radar Topography Mission) for 2D input (resolution: 3-arc-

second). However, to prevent long model run times and for practical reasons, it was determined that the

resolution was too high for this preliminary model. Data from GMTED2010 (Global Multi-resolution Terrain

Data 2010) is imported in the model after downloading it from the database and processing it to the right

format. See [Appendix 15 ] for an overview of the DEM map clipped for the Pampanga River Basin with the

1D model already imported. The resolution of the DEM map is 7.5-arc-second for the Philippines, indicating

that the horizontal and vertical resolutions are more or less 230 [m]. Since the unit of “vertical” (north-

south) and “horizontal” (east-west) resolution is in degrees, the horizontal and vertical resolution do not

match in meters, the unit that SOBEK uses for elevation data input layers. However, since the Philippines is

close to the equator, the resolution horizontally and vertically is nearly the same. In this modelling attempt,

it is assumed that both resolutions are also the same in meters. It is chosen to take the horizontal

resolution (dx) as model input for both the horizontal and vertical cell dimensions. For that reason, the

imported GIS-layer does not match perfectly with the DEM. The 1D-system is for that reason changed to

the outlines of the (slightly disproportionate) DEM-layer. The vertical resolution of the DEM (perpendicular

to the land surface) is one meter. This indicates that one has to be careful with just accepting values of the

DEM. Since the model will be made for a delta area, small elevation differences (much smaller than a

meter) are assumed to be essential in modelling of this relatively flat area. The amount of distinct

elevations in the model is pretty low in this region, with relatively small absolute elevation differences.

5.2.3 Boundary conditions

Five boundary conditions are implemented in the model. Three downstream boundaries give the water

levels as a function of time in Manila Bay at the outflow of Pampanga River, Labangan Floodway and Pasac

River. For simplicity, the water levels are fixed on 1.5 [m], more or less corresponding to the water level at

high tide in Manila Bay. One upstream boundary gives discharges of events with a certain return period for

the main discharging river, the Pampanga. Another upstream boundary gives discharges for the Angat

River, which will be 25% of the Pampanga River discharge.

5.3 Model results and discussion

This is a preliminary model and it is meant to give some first impressions in the behaviour of the delta

system. The peak discharge chosen for the Pampanga River in this model corresponds to a “once in five

years” return period. However, since there are no design discharges available, it is assumed that this

discharge intensity lasts for five consecutive days, with an ascending and descending limb from and to the

mean annual discharge. The discharge for the Angat River is also schematized. It is assumed that the

discharge here corresponds to the above mentioned 25% of the Pampanga. The run-time for the model is

one month, which more or less corresponds with the time that a big flood could take place. The time step

is chosen to be 12 hours, in order to prevent long model running times.

18

USGS (2013) 19

NASA (2014)


The first model outcome is not very representative. For the assumed discharge, it is not showing any

significant flooding of the delta area. It is expected that this is caused by the fact that the digital elevation

model from GMTED2010 has not very representative elevation values for the delta area. This could be seen

in Figure 5-1. One could see that at a certain point (30 [km] upstream from the boundary condition at

Manila Bay), the elevation of a tile around the river is 13 [m], while the elevation here should be around

3[m] 20. Also, closer to Manila Bay, the elevation of the land is higher than the regular floods in this area

would suggest. It is believed that the higher elevations in the GMTED2010 DEM are due to buildings and

vegetation along the Pampanga River and in the Pampanga Delta. For the Pampanga River, this could also

be seen in Figure 5-1. The model outcomes show water levels in the channels that increase to a value

corresponding to the lowest tile elevation along the Pampanga River. After this, a relatively small area

upstream is flooded, indicating that the model suggests that there is enough storage capacity in the river

for a “once in five years”-discharge.

Figure 5-1: High elevation and buildings along Pampanga River (Images/maps: Google, DigitalGlobe, Europa Technologies, 2014)

Because the first try did not give representative flooding results, it is determined to change the 1D-model

to ensure that the area will be flooded, as in the actual case. Since the 1D part of the model lies far below

the 2D part of the model, the most easy solution is to increase the 1D part of the model in elevation so that

the 1D-model elevations approach the values of the DEM tiles. The elevation of the entire 1D-system is

increased with 5 [m], leading to higher river beds and river banks as well. In accordance with the

expectations, this modelling approach gives significant flooding of the delta area, but again one has to be

careful with interpreting these results. At the end of the flooding event applied in the model, the delta area

is flooded like shown in Figure 5-2. One could see that especially many low-lying areas are flooded and that

many urban areas are still dry after the simulation. The legend is shown in [Appendix 15 ]. This is due to the

fact that urban areas are represented as higher areas due to high density of buildings. Striking are the deep

blue areas north-east of Calumpit. A possibility why the areas there are deep blue and thus heavily flooded

compared to the rest of the area, is that this region is surrounded by high elevation in the north and east

and by two rivers in the west and south. This way, discharge from these areas if somewhat difficult. Since

the elevation of the rivers is artificially increased and the digital elevation model in high density areas also

gives higher elevation, it is not sure to which extent the outcomes are representative for the real situation.

20



Figure 5-2: Flooded areas (in blue) after design runoff event with peak discharge with return period of 5 years

5.4 Preliminary validation

The preliminary model outcomes are validated with satellite images of flooded areas after a significant

storm. This model is compared to an image from Landsat 8 taken on October 18, 2013; more or less a week

after typhoon Nari (or Santi) hit central Luzon. The image from Landsat 8 is shown in Figure 5-3. Striking

similarities between the modelled flood map and the observed flood map are mainly visible north-east of

Calumpit (the deep blue areas). These areas are also flooded on the observed flood map. Also, the area

south-east of Calumpit shows some inundated areas that are flooded in the model. Although the image

from Landsat 8 seems to match with the modelled outcomes, this does not mean that the flooded areas

are solely caused by the particular storm, one week before typhoon Nari. We do not know what exact

influence historically high discharges have on inundated areas. What one can say about this model is that

some areas are indeed more susceptible to high river discharges than others.


Figure 5-3: Flood map Pampanga Delta after Typhoon Nari in 2013 together with main streams and Calumpit(Images: USGS, Landsat, 2013)

5.5 Conclusion As one could deduce from the results, this model is a first step in modelling the floods due to high river

discharges from upstream. It only approaches representative outcomes due to a lack of information. Also,

the information which is available is of poor quality. The river dimensions are all based on own

measurements and they are simplified due to temporal restrictions for visualization of reality. Furthermore,

the small streams in the delta area are neglected because of the same reason. This digital elevation model

gives a realistic, though not completely accurate two-dimensional representation of flood situations. The

available information about water levels and corresponding discharges in the Pampanga and Angat River is

considered not accurate enough for this type of modelling. In order to obtain better representations of

reality, a measurement program is proposed in addition to a plan to cooperate with an organization21

responsible for collecting high detailed 3D information in the Pampanga River basin.

5.6 Model improvement recommendations

The biggest reason why the SOBEK 1D2D model does not give representative outcomes is because there is

a limited amount of data available for free or in high quality. In this paragraph, solutions against this lack of

data availability are proposed.

21

Inquirer.net (December, 2012)


5.6.1 Drainage system dimensions

Since it is indicated that not enough information was available to put the cross sections of all channels of

the Pampanga Delta in the model, it is advised to set up a measurement program in the future. Measuring

cross sections is relatively easy; however, some essential equipment is necessary to achieve an efficient

measurement process. Since there are many (small) streams in the Pampanga Delta it is important to first

make sure that all streams are taken into account for the measurement program. This could be done by

identifying streams with satellite data, which is available these days. With these satellite data, the widths of

the rivers could also easily be determined.

5.6.2 Elevations of the flood prone areas

Since flood prone areas are generally low lying and only have a small gradient, it is necessary to obtain high

resolution elevation data before one could make a model of the system. The freely available digital

elevation models have a vertical resolution of 1 [m]. This resolution is too coarse for these low lying areas,

where elevation differences of 1 [m] could significantly change the response to water levels. Also horizontal

resolutions are too coarse and buildings and vegetation influence present elevation models. Furthermore,

these resolutions of freely available DEMs neglect the effect of small dikes which are omnipresent in the

Pampanga Delta, see Figure 5-4.

Figure 5-4: Small dike in Pampanga Delta around fish ponds


Since 2012, there is a measuring program for making high resolution elevation maps for flood prone areas

in the Philippines (NOAH/DREAM) 22. The measurement program DREAM (Disaster Risk and Exposure

Assessment for Mitigation) of the Nationwide Operational Assessment of Hazards (NOAH) works with the

so called LiDAR technique (Light Detection and Ranging) and is meant to make reliable, detailed and up-to-

date flood models of the eighteen major river basins and watersheds in the Philippines. In two years, high

resolution elevation maps and models will be made. With this technique, elevation models could be refined

up to house level, indicating that the problem of buildings and vegetation disturbing the quality of the

digital elevation model is past. It is advisable to contact this organization, responsible for making LiDAR

elevation maps, about the availability of data. This way, more organizations could make use of the data in

several models. This SOBEK-model of the Pampanga Delta will considerably benefit from the high

resolution LiDAR data.

5.6.3 Rainfall input data, water levels and discharges

Long-time rainfall data for statistically-based statements is currently available at ten rainfall stations (see

[Appendix 16 ]). Rainfall data is available at more stations; however, the time frame of the data series is

(assumed to be) too short for further analysis. In this research, this data is not used for further analysis,

although it can be used as model input data for a model of the entire Pampanga River Basin. No rainfall

data is available for the eight municipalities. This means that assumptions should be made for this area

(Kriging, TRMM).

Water level data at the downstream end is essential in modelling the behaviour of the floods coming from

the sea. In the described modelling approach, flooding from high water levels downstream is neglected,

although tidal flooding is a problem mainly in the southern parts of the Pampanga Delta. It is advisable to

place water depth/pressure meters at the downstream ends of certain streams in the Pampanga Delta to

create representative model inputs for the downstream end of the flood model.

Water level data is also essential for the upstream boundary conditions where it could lead to accurate

rating curves, for the discharge of the river could be determined as a function of the water level. These

rating curves are already available along for several places in the Pampanga River Basin, however the

reliability of these curves is questioned (see chapter [6.2]). It is advisable to take measurements at the

upstream boundaries of the model and to check them again after a certain time, due to the dynamic

character of the physical river system.

22

NOAH (2014)



6 Advanced Model Input A detailed hydrodynamic model for a clear overview of the water system in the area is crucial before

solutions for the flooding problem could be proposed, see Chapter 5. Since making a high detailed

hydrodynamic model falls out of the scope of this research, this chapter will mainly focus on model input

parameters, physical system properties and boundary conditions which could be valuable to take into

consideration when making a hydrodynamic model. The area lies downstream of the Pampanga River

Basin, where several river branches from the entire river basin end up in the Pampanga Delta, the study

area of this research.

6.1 Rainfall analysis Extreme rainfall in the Pampanga River Basin is the most important factor causing upstream flooding in the

Pampanga Delta. Therefore, rainfall will be the most important input parameter in the future

hydrodynamic model. An analysis on rainfall measurements will help to design standardized rainfall events,

which can be implemented in the future model. Rainfall measurements are available throughout the

Pampanga River Basin. Since not every rainfall station has the same times of operation, for simplicity only a

part of the rainfall stations is selected for rainfall analysis. Ten rainfall stations are selected all with data

gathered between 1974 and 2008. See Figure 6-1 for an overview of the locations of the rainfall stations in

the Pampanga River Basin. The names of the rainfall stations taken into consideration in this research are:

1. Sapang Buho

2. Zaragoza

3. Papaya

4. San Isidro

5. Arayat

6. Candaba

7. Sibul Spring

8. Sulipan

9. Ipo Dam

10. San Rafael

6.1.1 Rainfall availability

The data coverage for all ten rainfall stations is not complete, meaning that some data in the time interval

1974 – 2008 is missing. This lack of data availability could have several causes. Some examples of causes

are vandalism of the rainfall station or lack of operational efforts. Since the data supplier (PRFFWC23) does

not give exact clues about this, the cause of the lack of data availability will be disregarded in this research.

An overview of the percentage of days without data records is shown in Table 6-1. The fact that data is

missing also indicates that data availability is not only a problem on a yearly scale, but could also be a

problem on a daily scale. Data is collected per hour and the cumulative rainfall is exported to a daily sum.

One can imagine that if data on some hours during the day is missing, the outcome is a lower daily output

than the value is supposed to be. After taking data samples and checking them for non-complete daily

rainfall series consisting of the cumulative rainfall in 24 hours, one can conclude that this problem is

relatively small. For this reason there is assumed that the daily rainfall is the cumulative of 24 hours of

rainfall on that particular day.

23

PRFFWC (2013)


Table 6-1: Percentages of days of no data records in rainfall stations

Sapang Buho Zaragoza Papaya

San Isidro Arayat Candaba

Sibul Spring Sulipan

Ipo Dam

San Rafael

% 16,3 12,5 12,8 11,5 15,1 18,3 11,0 9,9 12,2 11,7

Figure 6-1: Locations of used rainfall stations in Pampanga River Basin(Images/maps: Google, TerraMetrics, 2014)

6.1.2 Analysis methods

There are several methods to do rainfall analysis in a specific area of interest. In this research, two research

methods are tried and the outcomes will be discussed and recommendations are done for the rainfall data

that one has to take into account to put in the model. Both methods are based on producing depth-

duration-frequency curves and intensity-duration-frequency curves of rainfall in specific areas. By means of

these curves, rainfall events could be designed which could be part of the input of the future hydrodynamic

model.

Floods could be caused by different rainfall durations. For example a rainfall event of one day could have

the same effects on floods in a region as a rainfall event of 10 days, with the only difference that the

rainfall depth is more spread over the time for a 10 day rainfall event. In this research, it is assumed that a

flood in the Pampanga Delta will not be caused by rainfall events which take longer than 10 days and not

shorter than one day. For this reason, four rainfall duration times are chosen for the rainfall analysis. The

shortest rainfall duration time is set on k=1 day, the second on k=2 days, the third on k=5 days and the last

rainfall duration is set on k=10 days. These four rainfall durations are plot on the x-axis of the depth-

duration-frequency curves and the intensity-duration-frequency curves. These curves are made for

different return periods. In this research, it is chosen to use the return periods T=2 year, T=5 years, T=10

years, T=20 years, T=50 years and T=100 years. By means of these different time scales for rainfall return


periods, models could be made for frequently occurring natural scenarios (for T=2 year and T=5 year) or

scenarios that take longer before they occur again (for T=10years, T=20 years, T=50 years and T=100

years).

For the two methods regarding rainfall analysis in this research, the main difference is the amount of data

that is needed from rainfall stations to do the analysis. One method needs all the daily rainfall values

between the years 1974 and 2008, while the other method only uses the annual maximum rainfall values

for the four predefined rainfall duration times. These two methods are explained in the paragraphs below.

6.1.3 Analysis of annual extreme precipitation

The analysis of annual extreme precipitation makes use of the so called annual extremes of rainfall values

for the ten rainfall stations24. For the period of 1974 until 2008, the maximum daily, 2-days, 5-days and 10-

days precipitation amounts are filtered from the daily precipitation list. An example of the maximum

amounts for one rainfall station (Zaragoza) in the Pampanga River Basin is shown in Table . One has to take

into account that this list only shows the maximum precipitation measured on one, two, five and ten days,

so from 0 [h] until 24 [h] on a day. Maximum rainfall numbers measured in 24 [h] spread over two calendar

days etcetera are not taken into account.

Table 6-2: Annual maximum daily, 2-day, 5-day and 10-day rainfall amounts for rainfall station Zaragoza

year 1 day 2 days 5 days 10 days year 1 day 2 days 5 days 10 days

1974 210 328 414 460 1992 112 112 123 175

1975 71 120 186 235 1993 136 224 252 269

1976 146 203 417 554 1994 97 112 119 199

1977 115 163 177 177 1995 71 87 140 182

1978 85 149 189 233 1996 102 102 133 216

1979 165 181 210 332 1997 104 182 278 314

1980 135 258 292 410 1998 112 159 242 341

1981 89 106 195 240 1999 170 286 381 398

1982 140 142 147 287 2000 219 228 320 378

1983 43 61 83 95 2001 58 65 80 108

1984 151 188 202 304 2002 120 163 343 483

1985 98 99 99 105 2003 100 152 195 239

1986 148 224 324 354 2004 144 279 327 407

1987 168 178 188 255 2005 68 89 102 115

1988 124 169 215 296 2006 112 120 143 210

1989 68 78 148 158 2007 65 72 144 183

1990 154 169 199 362 2008 65 95 133 180

1991 124 219 227 244

After this first step, the data are ranked in descending order per year, like shown in Table 6-3 for a rainfall

event of 1 day. After this the probability of exceedance P is calculated with the formula:

24

Savenije, 2007


In this formula, n is the number of years of record and m is the rank number of the event. The return

period T is calculated by dividing 1 through the probability of exeedance (T=1/P) and the probability of non

exceedance q with the formula q=1-p. With this information, one can introduce a new parameter y, the

reduced variate which is a function of q (and thus also of P and T).

( ( )) ( ( )) ( (

))

This parameter y makes it possible to linearly plot the rainfall-depth relation. This means that easy linear

equations could be made to give a relation between the rainfall depth and the reduced variate y. Since

there are different return periods, this way one can also calculate the reduced variate y per return period

and this value could be filled into the linear equation describing the relation between the rainfall depth and

the reduced variate y. A calculation of the values for the reduced variate y for the predefined return

periods give:

T= 2 years: y= 0.37

T= 5 years: y= 1.50

T= 10 years: y= 2.25

T= 20 years: y= 2.97

T= 50 years: y= 3.90

T= 100 years: y= 4.60

Table 6-3: Rank, probability of (non-) exceedance, return period and reduced variate for rainfall station Zaragoza for daily precipitation amounts

year rank

Rainfall depth (mm) P T q y

year rank

Rainfall depth (mm) P T q y

2000 1 219 0,03 36,00 0,97 3,57

1998 19 112 0,53 1,89 0,47 0,29

1974 2 210 0,06 18,00 0,94 2,86

2006 20 112 0,56 1,80 0,44 0,21

1999 3 170 0,08 12,00 0,92 2,44

1997 21 104 0,58 1,71 0,42 0,13

1987 4 168 0,11 9,00 0,89 2,14

1996 22 102 0,61 1,64 0,39 0,06

1979 5 165 0,14 7,20 0,86 1,90

2003 23 100 0,64 1,57 0,36 -0,02

1990 6 154 0,17 6,00 0,83 1,70

1985 24 98 0,67 1,50 0,33 -0,09

1984 7 151 0,19 5,14 0,81 1,53

1994 25 97 0,69 1,44 0,31 -0,17

1986 8 148 0,22 4,50 0,78 1,38

1981 26 89 0,72 1,38 0,28 -0,25

1976 9 146 0,25 4,00 0,75 1,25

1978 27 85 0,75 1,33 0,25 -0,33

2004 10 144 0,28 3,60 0,72 1,12

1975 28 71 0,78 1,29 0,22 -0,41

1982 11 140 0,31 3,27 0,69 1,01

1995 29 71 0,81 1,24 0,19 -0,49

1993 12 136 0,33 3,00 0,67 0,90

1989 30 68 0,83 1,20 0,17 -0,58

1980 13 135 0,36 2,77 0,64 0,80

2005 31 68 0,86 1,16 0,14 -0,68

1988 14 124 0,39 2,57 0,61 0,71

2007 32 65 0,89 1,13 0,11 -0,79

1991 15 124 0,42 2,40 0,58 0,62

2008 33 65 0,92 1,09 0,08 -0,91

2002 16 120 0,44 2,25 0,56 0,53

2001 34 58 0,94 1,06 0,06 -1,06

1977 17 115 0,47 2,12 0,53 0,45

1983 35 43 0,97 1,03 0,03 -1,28

1992 18 112 0,50 2,00 0,50 0,37


6.1.4 Results

For all the rainfall stations in the Pampanga River Basin, the above mentioned process is performed. Due to

the plenitude of figures, in this report only the rainfall plots for Zaragoza are shown. From the Gumbel-

distributions, the depth-duration-frequency curves are performed just like the intensity-duration-frequency

curves (see respectively Figure 6-3, Table 6-4, Figure 6-4 and Table 6-5).

Figure 6-2: Gumbel distributions Zaragoza with k=1d (upper left), k=2d (upper right), k=5d (lower left) and k=10d (lower right)

Figure 6-3: Depth-Duration-Frequency curves for rainfall station Zaragoza

0

200

400

600

800

0 2 4 6 8 10 12

Rai

nfa

ll d

ep

th (

mm

)

Duration (days)

Depth-Duration-Frequency curves Zaragoza

T=2

T=5

T=10

T=20

T=50

T=100


Figure 6-4: Intensity-Duration-Frequency curves for rainfall station Zaragoza

Table 6-4: Values DDF curves rainfall station Zaragoza

Rainfall depths Zaragoza (mm)

k=1 k=2 k=5 k=10

T=2 111 149 196 254

T=5 152 215 288 366

T=10 179 259 348 440

T=20 205 301 406 511

T=50 239 356 481 602

T=100 264 397 537 671

Table 6-5: Values IDF curves rainfall station Zaragoza

Rainfall intensities Zaragoza (mm/d)

k=1 k=2 k=5 k=10

T=2 111 74 39 25

T=5 152 108 58 37

T=10 179 130 70 44

T=20 205 151 81 51

T=50 239 178 96 60

T=100 264 198 107 67

6.1.5 Analysis of rainfall with cumulative frequency curves

The analysis of rainfall with cumulative frequency curves makes use of the same rainfall data as in the

analysis of annual extreme precipitation. However, in this case not only the annual extremes are used for

the different rainfall durations, but all the (available) data25. It is expected that this method will give

different depth-duration-frequency curves and intensity duration frequency curves due to the limited data

25

Savenije, 2007

0

50

100

150

200

250

300

0 2 4 6 8 10 12

Rai

nfa

ll in

ten

sity

(m

m/d

)

Duration (days)

Intensity-Duration-Frequency curves Zaragoza

T=2

T=5

T=10

T=20

T=50

T=100


availability and the fact that the “resolution” of the data is only 1 [mm]. This means that especially during

low intensity rainfall events, the relative difference between real rainfall and measured rainfall could be

high.

The analysis starts with making an overview of the amount of consecutive days in the period between 1974

and 2008, which lie in a certain class interval of rainfall amounts for a rainfall period of 1, 2, 5 and 10 days

(i.e. there is an amount of 250 rainfall periods with a length of 5 days with a rainfall intensity higher than 50

mm). The values in this overview are converted to repetition times by applying the following formula:

With ‘total time periods the total amount of time periods of 1,2,5 and 10 days in the period 1974 – 2008.

The ‘classified time periods’ are the amount of time periods falling in a certain class interval (mm) for

certain rainfall periods. After this the return periods T are plot against the rainfall depths for the rainfall

periods of 1,2,5 and 10 days. The created graph is a so called cumulative frequency curve. With this curve,

depth-duration-frequency curves and intensity-duration-frequency curves could be made.

6.1.6 Results

For all the rainfall stations in the Pampanga River Basin, the cumulative frequency curves are made

together with the depth-duration-frequency curves and intensity-duration frequency curves. Due to the

plenitude of figures, in this report only the rainfall plots for Zaragoza are shown. In the cumulative

frequency curves, only return periods higher than 0.5 year are plot, due to fact that the main interest is in

high rainfall intensities and not in low rainfall intensities. This way the values are extrapolated for longer

return periods only. The cumulative frequency curve for the rainfall station in Zaragoza is shown in Figure

6-5 with the return period on a logarithmic scale. For the depth-duration-frequency curves and intensity-

duration-frequency curves see Figure 6-6 and Figure 6-7. The corresponding values are shown in Table 6-6

and Table 6-7.

Figure 6-5: Cumulative frequency curves rainfall station Zaragoza

y = 0,0434e0,0311x y = 0,0322e0,0224x y = 0,0218e0,0147x

y = 0,0035e0,0148x

0,1

1

10

100

1000

0 200 400 600 800

Re

turn

pe

rio

d (

y)

Rainfall depth (mm)

Cumulative frequency curves Zaragoza

k=1

k=2

k=5

k=10

Expon. (k=1)

Expon. (k=2)

Expon. (k=5)

Expon. (k=10)


Figure 6-6: Depth-Duration-Frequency curves for rainfall station Zaragoza

Figure 6-7: Intensity-Duration-Frequency curves for rainfall station Zaragoza

Table 6-6: Values DDF curves rainfall station Zaragoza

Rainfall depths Zaragoza (mm)

k=1 k=2 k=5 k=10

T=2 123 184 307 429

T=5 153 225 370 491

T=10 175 256 417 538

T=20 197 287 464 585

T=50 227 328 526 646

T=100 249 359 574 693

0

100

200

300

400

500

600

700

800

0 2 4 6 8 10 12

Rai

nfa

ll d

ep

th (

mm

)

Duration (days)

Depth-Duration-Frequency curves Zaragoza

T=2

T=5

T=10

T=20

T=50

T=100

0

50

100

150

200

250

300

0 2 4 6 8 10 12

Rai

nfa

ll in

ten

sity

(m

m/d

)

Duration (days)


T=2

T=5

T=10

T=20

T=50

T=100


Table 6-7: Values IDF curves rainfall station Zaragoza

Rainfall intensities Zaragoza (mm/d)

k=1 k=2 k=5 k=10

T=2 123 92 61 43

T=5 153 113 74 49

T=10 175 128 83 54

T=20 197 144 93 58

T=50 227 164 105 65

T=100 249 179 115 69

6.1.7 Discussion on rainfall analysis

As one can see from the depth-duration-frequency curves and intensity-duration-frequency curves from

the two rainfall analysis methods, is that the results for the analysis with cumulative frequency curves give

higher values than the analysis with annual extreme precipitation amounts. This is not only the case with

the rainfall values for rainfall station Zaragoza, but also in nearly every rainfall station.

Since it is not clear which analysis gives the best results, one cannot say anything about the best depth-

duration frequency curves or intensity-duration-frequency curves for the area. There are some striking

points that one has to take into account before one decides to make use of certain rainfall analysis

outcomes.

One point is that there is a significant amount of data missing in the data series, around 13% of all the

rainfall data. Sometimes entire months are missing for a rainfall station or sometimes even large parts of

the year. This indicates that more rainfall events take place in reality. In the two analyses, the days without

data are considered as dry days. This is not correct of course. For this reason, both the depth-duration-

frequency curves and intensity-duration-frequency curves should give higher values for both analyses.

Since the lack of available data series and the two varying outcomes of the rainfall analyses give uncertainty

about the use of the reliability of the analyses, only intensity-duration-frequency curves from the analysis

with annual extreme precipitation amounts are given in [Appendix 16 to prevent indistinctness. If one

decides to use these values for modelling, one has to make sure to at least increase the values with a

certain factor in proportion to the amount of missing data. It is advised to do some further analysis to get a

better understanding about rainfall amounts in the area.

6.2 River Runoff

The conversion from rainfall to runoff is a crucial hydrological connection. For the Pampanga delta it is

important for the following reasons:

It provides information on expected fluvial flooding scenarios;

It can be used to forecast fluvial floods as rain can be forecasted several days.

Rainfall runoff modelling is somewhat more an art than a science. This can be explained partially by the

difficult route that raindrops take to the rivers and partially by uncertainty in data sources. Rainfall data is

available26, although by definition it has quite some uncertainty. To be able to make the rainfall runoff

26

PRFFWC (2013)


connection reasonably well, reliable runoff ground data should be available, obtained by many stream flow

measurements.

Figure 6-8 - Water height gauges27

(Images/maps: Google, TerraMetrics, 2014)

Typically, water heights are measured to be converted to stream flows. Hourly water height data is

available for at least several years on the stations displayed in Figure 6-8. These water heights seem

reliable but converting them to stream flows is problematic.

The stations Sulipan, Sasmuan, Candaba and Arayat can be observed to have a strong tidal influence. This

means that it is not possible to use a simple rating curve, as time variation plays a big role whereas rating

curves are based on equilibrium flows.

Unfortunately the stations San Isidro, Peqaranda and Mayapyap do not show any low flows, which is

probably erroneous, since the upstream station Sapang Buho does show them. Low flows are quite

important to properly model rainfall runoff behaviour. Thereby, the available rating curves come with one

calibration parameter only, which seems to indicate that only few stream flow measurements have been

taken to obtain this curve. This means these curves will not give an accurate conversion from water height

to stream flow and are not elaborated further.

27

Google Earth


7 Salt Intrusion

7.1 Introduction Salt intrusion is an important aspect to consider in an agricultural area which might be subject to change.

As it depends on the behaviour of the whole system, it is a complicated aspect. Analytical relations

obtained by simplification can show which parameters are important. These parameters can be used for

qualitative analysis. They can be directly obtained from measurements, or indirectly derived from other

information. The quality of quantitative analysis depends heavily on measurements and can be improved

over time by continued measuring.

7.2 Parameters

The following parameters are important:

The average water depth [m]

H The tidal range (the difference between high tide and low tide) [m]

E The tidal excursion (~ the distance water moves up and down the estuary in a tidal period) [m]

K A mixing coefficient (a measure for the salt mixing in the estuary)

The first three parameters can be seen as a summary for the tidal dynamics, whereas the mixing coefficient

is a lumped, empirical variable that quantifies the salt mixing process. The analytical model used here

simplifies the intrusion process to a salt curve that moves up and down as the tides moves in or out of the

estuary. All of these parameters will slowly change, forced by nature. When considering a bigger timescale,

like 100 years, they should all be taken into account.

As a flooding related aspect, the water depth is important, since it can be changed rapidly when adjusting

the system in order to prevent flooding 28. Dredging is a measure that has often been mentioned to ‘solve’

the flooding problem.

Another parameter that might be able to change in a short period of time is the mixing coefficient. The

mixing is related to water depths. In a heavily interconnected delta like the Pampanga delta, horizontal

circular motion will be important when determining the mixing. Thereby measurements have shown that

confluences and bifurcations play a big role in mixing. What is a confluence for flow in one direction is a

bifurcation for flow in the other direction. Sea water that enters the estuary often flows into bifurcations as

it fills up all the small side canals. As the water flows out with the retreating tide, water with different salt

concentration meets in the confluences and mixes. Therefore much mixing takes place in the estuary when

the tide retreats.

Measures against flooding will most likely influence the water depths and therefore the mixing process.

The resulting influence on salt intrusion should be taken into account when designing these measures. A

first attempt to quantify the phenomenon is done with analytical relations.

28

Savenije (2007)


7.3 Tidal dynamics

Depth measurements were performed in the whole estuary. Thereby depth variation measurements were

taken on two locations on the estuary, the mouth of the Pampanga River and further upstream the

Pampanga, at the Barangay Sulipan in Calumpit. Combining the depth measurements with the depth

variation measurements the wet cross sections are obtained. From these cross sections the average depths

and the convergence length have been determined. Thereby the tidal range has been derived from these

measurements where the largest value has been used, which occurs at spring tide.

Using the phase lag equation and the geometry tide relation, the tidal excursion has been computed29.

Even though salt measurements or numerical models can give a more accurate computation of the tidal

excursion for each location, this gives a good idea of its magnitude. A computed value for the tidal

excursion is ~16 [km], (see [Appendix 17 ]). With the right timing of water intake for irrigation, a stretch of

a half to three quarters of the tidal excursion can be irrigated with fresh water, when comparing with the

system of taking in water when it is highest with the simple system of weirs (overlets).

29

Savenije (2012)

( )

( )

( )

Phase lag equation:

The angular velocity, related to the tidal period

c The long wave celerity, the speed with which the wave propagates (√ )

b The convergence length, a measure for convergence

The damping coefficient, a measure for damping of the wave height

Geometry tide relation:

The average water depth

The storage/width ratio

H The tidal range


7.4 Intrusion curve

Due to a lack of availability of speedboats, no salt measurements have been taken in the Pampanga River.

The envelope method where the salinity at low and high water slack are measured requires a boat that

goes faster than the wave celerity, which means around 30 [km/h] for the Pampanga river.

Therefore this method can only provide a rough estimate of the salt intrusion curve, by using predictive

equations. These equations have been obtained from measurements on many estuaries over the world.

However, they might not have contained comparable complex geometry as in the Pampanga delta and

therefore measurements should definitely be taken.

The shape of the salt intrusion curve is empirically computed with the mixing coefficient. An estimated

value for K has been computed using a predictive equation. In Figure 7-1 a first attempt to mimic the salt

intrusion curve in the Pampanga River is shown. Here LWS is the minimum intrusion at low water slack, TA

is the tidal average intrusion and HWS is the maximum salt intrusion at high water slack.

Figure 7-1 - Predicted salt intrusion curve in the Pampanga River


7.5 Salt measurements in Hagonoy

Salt measurements have been taken in Hagonoy to demonstrate the theory and to be used by these people

living in the current frontier of where salt intrusion makes it difficult for rice farming. Figure 7-2 shows the

measured concentrations on several bridges over the Hagonoy River. A difficulty was that high water slack,

where the maximum concentration at each location can be measured, kept occurring at night. Therefore

we do not have maximum values. This means that the maximum of the envelope consisting of the

maximum and minimum values is bigger than we can show in the measurements. The horizontal distance

between the two lines is the tidal excursion and the vertical distance shows how much the salinity varies on

each location.

When comparing the Hagonoy River to the Pampanga River, there is a big difference in size. As the depth in

the Hagonoy is a lot smaller, the tide has more difficulty moving up and down in the Hagonoy River and

therefore the tidal excursion is a lot smaller here. This can also be seen from the salt measurements, where

the increasing salt concentration in the tail shows that water from the Pampanga River enters the Hagonoy

River through the backdoor, Hagonoy’s upstream end.

Figure 7-2 - Tidal excursions (horizontal axis) and relative concentrations (vertical axis) in Hagonoy River


7.6 Recommendations

As the salt intrusion curve moves up and down the estuary, it is important to have the right timing when

taking out water for irrigation. At each location there is a maximum and a minimum salinity, respectively at

high water slack and at low water slack. For irrigation it follows that water should be taken in at low water

slack tide, when it is as fresh as it is going to get. But in practice, normal intake structures react on water

heights rather than water movement.

Along the pathway of a fixed volume of water which may be assumed to have a constant salt concentration

and is moving with the average stream velocity, different water heights can be observed. For the shape of

this curve the convergence of the cross sectional area is crucial. A typical example, comparable to the

Pampanga River, is displayed in Figure 7-3, where the x-axis is directed positive upstream.

Figure 7-3 – Salt particle movement

In the project area many intakes for irrigation have been observed to be weirs. They take in water when it

is high tide. This means that they take in water which at that time is in between half to fully its tidal

excursion inland, and therefore they take in water which is relatively salty.

By changing to constructions which can take in water at low water slack tide, the front line of irrigated rice

area which has problems with salinity can be moved this distance downstream. This is a difference of ~10

[km] and therefore significant. The constructions could for example be gates. The exact timing can be

determined simply by using a float with a long rope attached to an anchor. When this float starts moving

upstream, slack tide has arrived. Also without these indicators, the fishing community will be fully aware of

this moment, as they have to move to the other railing of the bridge.



8 Land Use Changes

8.1 Problem description For several decades, crop yields of rice paddies lower to the point that growing rice on these fields is not

profitable anymore. Farmers come up with different reasons for the decrease in crop yield. There are

mainly two reasons (see [Appendix 19 ]). First, there is the group that thinks that crop yields decrease

because of the fact that there are more floods in the last decades. Water quantity is the issue, according to

this group. Second, there is the group of farmers that thinks that water quality is mainly the issue. For

them, salt intrusion is considered as the main issue for decrease of crop yields in the area.

The big problem is not only that rice fields are depleting in the coastal municipalities, because of floods, but

it is also possible to use the land for other opportunities, like fishponds, which generate more money than

conventional rice paddies. A significant problem is that changing rice fields into fishponds takes a lot of

manpower and thus money. Rice is ideally planted on a paddy with low water levels. The water level needs

to be increased if the rice plants grow. After a few months, the water level should be increased to get good

rice yields. However, fish ponds need higher water levels (about one meter) for ideal growing conditions. In

this region it is often not possible to just increase the water level on the rice paddies to make aquaculture

possible, for the fields have to be deepened and dikes heights around the ponds need to be increased. The

price of this process is approximately [₱3,000,000.00/ha] (see [Appendix 19 ]).

Another problem is that the change from rice paddies to fishponds results in a reduction of employment

rate. For growing rice – dependent on the time of the year – there are daily many people on the field to do

the labour. For fishponds, most of the time there are no labourers necessary (see [Appendix 19 ]). The

result of this is a big shift in the local economy and employment.

8.2 Introduction research plan

Insight in the changes of the situation could lead to a better understanding of the land use change in the

past and could also lead to more considered decisions about land use in the future. Since there are mainly

two types of rural surface areas in the eight municipalities – rice paddies and fishponds – it would be useful

to find a way of monitoring the land use over time.

If one takes a look into the physical properties of rice paddies and fish ponds, the main difference is that

rice fields – for a large part of the year – consist of plant material, while fish ponds are covered with water

during the same period. The latter sometimes only get dry during harvesting of the fish. A good way of

distinguishing these two land use types is by optical distinction. Both land use types reflect different wave

lengths with different intensities. If it is possible to find certain wavelengths for optical distinction of land

use, one can (in theory) easily make a classification for the land use type at a certain moment. Since there

are optical satellite pictures freely available in different spectra, these pictures could be used for the

classification.

Satellite images of certain areas are made in multiple bands of the light spectrum. Some of these bands are

located in the visible spectrum for humans. Other spectral bands consist of wavelengths that are higher or

lower than the human eye could perceive. Two spectral bands that could significantly contribute to

distinguishing the difference between rice paddies and fish ponds are the so called “red band” and the

“near infrared band” (NIR band). This “red band” is visible for the human eye, while the “near infrared

band” is not. There is a big difference in the reflection of near infrared light between plants (rice paddies)


and water. Plants reflect significantly more near infrared light to space than water (e.g. fish ponds) does.

Together with the wavelengths of the “red band”, one can set up a ratio, the so called Normalized

Difference Vegetation Index (NDVI).

( ) ( )

The value of the NDVI theoretically varies between the extreme values -1 and 1. A value far below zero

corresponds with water, a value around zero with areas of rock or sand, and values approaching 1

correspond with very dense vegetation. According to these simple rules, the NDVI value of areas with a lot

of fish ponds should approach a value (far) below zero, while the NDVI value of areas with mainly rice

paddies should be positive somewhere between the NDVI of rock and sand and very dense vegetation.

8.3 Data availability, preconditions and constraints

Land use data in shape files is already available in a limited amount, obtained from PRFFWC 30; however,

this information only indicates the land use on a one single moment in time without insight in the dynamics

of the land use in time. The last time the shape file was changed was on March 10, 2010 indicating that this

shape file represents the land use on a moment before this date (see [Appendix 18 ]).

Data for temporal analysis of the land use change is downloaded from a database of the United States

Geological Survey (USGS) 31. On this database, the USGS EarthExplorer, (historical) data from several

satellites is available for downloading or could be requested for processing. Data used in this research

comes from satellites involved in the Landsat program. This program, which is running from July 23, 1972

until present day, collects images of everywhere on Earth in several spectral bands for use in diverse

applications of global climate change research and overall Earth observation. The Landsat mission consists

of several individual satellites covering the Earth for different time intervals. In this research, data will be

used from multiple Landsat satellites that have been in operation for the area of interest.

The suitability and quality of the data is dependent on several factors. One has to take into account that

sensors on the Landsat satellites obtaining the information from the Earth are optical sensors. This means

that the obtained information is dependent on the reflection of sunlight on the Earth surface. A picture

taken in the night is not useful, because sunlight is not reflected and areas of interest are not visible on the

images. Another disadvantage of obtaining data this way is that one is dependent on weather conditions.

No data can be obtained if the area of interest is covered with clouds. Since most of the obtained

information consists of reflected sunlight, the quality of the information is also a bit dependent on the

position of the sun, even during daytime.

The NDVI of the area of interest will be related to land use here. This NDVI ratio, which consists of two

theoretical spectral bands, is dependent on the wavelength intervals of the satellites covering these

spectral bands. These intervals are not the same for all Landsat satellites. Because of that, using the exact

values for NDVI of predefined pixels in the area is not a good method to do quantitative statements about

the land use. The way of land use determination for this research is through comparison of NDVI of all

pixels in the area with each other. According to the theory, areas of water (fish ponds and rivers) should

conflict significantly with other categories of land use in NDVI value.

The following files downloaded from USGS EarthExplorer are used for the land use investigation:

30

PRFFWC (2013) 31

USGS (2013)


LM21240501976058AAA05 (February 27, 1976), band 5, band 6

LT41160501989025XXX07 (January 25, 1989), band 3, band 4

LE71160502002365SGS00 (December 31, 2002), band 3, band 4

LC81160502013147LGN00 (May 27, 2013), band 4, band 5

The data is only chosen for the time period between November and May; this to prevent wrong image

interpretation. The time from June till October/November is considered as the rainy season when also

most of the floods occur. The chance is relatively high that images are chosen with flooded areas, which

are dry outside the rainy season.

8.4 Data processing

After downloading data from the USGS database via Earth Explorer, the useful information corresponding

to the demanded information to produce NDVI maps is opened in GIS program QGIS. We chose to use QGIS

for data processing, because it is an open source package. NDVI maps are made by applying the QGIS raster

calculator. After this, the NDVI maps are imported in GRASS via the GRASS plug-in. With this plug-in, the

NDVI maps are coloured according to a colour scheme appropriate for NDVI representation. Negative

values get bluer, positive values get greener. Around zero the NDVI colours are white or brown. See Figure

8-1 for an overview of the colour distribution (legend) of the NDVI value range.

Figure 8-1: Legend of NDVI values in QGIS


8.5 Results

In this chapter, an overview of the land use in the area will be given with significant time intervals, to show

if and how the land use is changing over significant units of time. A line visualizes the so called edge

between the area where there are mainly fish ponds and the area where there are mainly rice paddies in

the rural area. Extensions of urban areas are not considered in this analysis. Although the values on

different NDVI maps do not match for not changing land use, one can clearly distinct the different types of

land use on the separate NDVI maps after some practising. Small circles on the land use maps indicate

interview locations for land use validation, purple lines and areas indicate (relatively large) water bodies

according to the information obtained from PRFFWC32.

8.5.1 Land use in 1976 (February 27)

Figure 8-2: Land use map - NDVI, February 27, 1976 (Images: USGS, Landsat, 1976)

One can clearly see on the land use map (Figure 8-2), created with Landsat 1 data from 1976, that the fish

ponds are mainly concentrated in the southern areas of the eight municipalities. Focussing on Hagonoy,

the only areas with fish ponds are the southern barangays. The fish ponds do not go further north than the

urban parts of the barangays San Pascual, Santa Cruz, Santo Rosario, Sagrada Famila and Santa Elena. Also

the coastal barangays San Roque, Pugad and Tibaguin deal with fish ponds already. The area in the south is

also not completely white and blue. Obviously, there are also parts with vegetation or other land types

32

PRFFWC (2013)


than fish ponds. Another striking thing is that the area in the west, in the municipalities Macabebe and

Masantol, is still largely planted with rice or vegetated in another way. The soft light pink, purple and light

blue circles indicate the locations of the land-use validation interviews done during the fieldwork.

8.5.2 Land use in 1989 (January 25)

Figure 8-3: Land use map - NDVI, January 25, 1989 (Images: USGS, Landsat, 1989)

On the map from January 25, 1989 shown in Figure 8-3, one can clearly see that the edge between rice

paddies and fish ponds has shifted northwards related to the edge on the land use map of 1976. Barangays

of Hagonoy, which are adapted to fish ponds are according to this map: San Jose, Mercado, San Nicolas,

San Sebastian, Santo Niño, San Pablo and parts of Santa Monica. However, the land use change seems to

be the most severe in the western part of the eight municipalities: Masantol and Macabebe, in relation to

the land use in 1976. This part of the area is located in the area where the Pampanga River and its

tributaries are situated. In the east, the land use shift does not seem to change significantly. There are no

large discharging rivers situated in this region, only tidal creeks.


8.5.3 Land use in 2002 (December 31)

Figure 8-4: Land use map - NDVI, December 31, 2002 (Images: USGS, Landsat, 2002)

The first striking thing on the map in Figure 8-4 is that the NDVI values of the entire area are generally

lower than the values of 1976 and 1989. This has not to do with the fact that the total area became wet.

The rain meters in the catchment do not show significant rainfall amounts for the time prior to the timing

of this map. For this reason, it is assumed that the shift in colour pattern is related to the reflection

parameters of the light. The colour white is in this case thus not per definition related to water. If one

compares the fish pond area from this year with the area of fish ponds of 1989, the major land use change

took place again in the western parts of the municipalities, where the Pampanga River is located. In

Hagonoy, several barangays had to deal with land use change during these years. The barangays are:

Tampok, San Miguel, San Agustin and San Pedro. The blue and white area in the northeast of the eight

municipalities around Malolos is not related to water because of fish ponds, but it is caused by cloud cover

on the moment that the images are taken.


8.5.4 Land use in 2013 (May 27)

Figure 8-5: Land use map - NDVI, May 27, 2013 (Images: USGS, Landsat, 2013)

The map in Figure 8-5 shows a lot of absolute colour differences compared to the previous land use maps.

The reason for this is that for this map another satellite is used for image production. This satellite (Landsat

8) uses different spectral intervals for the red band and the near infrared band. For this reason, the NDVI

values of images taken with this satellite and the NDVI values of other satellites do not match. The areas

that were involved in land use change in the time interval from 2002 until 2013, are mainly areas around

the Labangan Channel (Paombong and Hagonoy) and the Pampanga River (Macabebe). In Hagonoy, the

barangays affected by the land use change between 2002 and 2013 are San Isidro, San Juan, Palapat,

Carillo and Abulalas. Iba and Iba-Ibayo are the only two barangays which are not subjected to significant

land use change now.


8.6 Validation of land use

The land use information obtained from satellite data will be validated by means of field interviews. People

living in the area are asked what type of land use is present in the area of the field interview. The location

of the field interview is marked by creating a waypoint on the location of the interview with a GPS device.

By means of this fact, the remote sensed information is checked in the field. For the field interviews, mainly

people from older generations are consulted on the fields, because they generally have a better insight in

the land use change over the years than the younger generation. An overview of the interviews itself is in

[0]. The interviews are conducted on two days. On the first day (December 20, 2013), two groups went in

the field by tricycle. The first group went from Calumpit down south till the southernmost barangay of

Hagonoy, the second group went from Calumpit down south till the southernmost barangay of Paombong.

On the second day, one group went from Malolos to Hagonoy more or less perpendicular to the routes on

the first interview day. In Figure 8-6, an overview of the locations of the interviews together with the

corresponding waypoint numbers is shown.

Figure 8-6: Locations of land use interviews including waypoint numbers (Images/maps: Google, TerraMetrics, 2014)

On all the locations, it was asked what the current land use is and how the land use evolved during the

years. In Table 8-1, a schematic overview is given from the answers obtained during the interviews

regarding land use, including current land use, former land use and timing of significant land use change.


When these validation results were compared to the remotely sensed data, the information from the land

use maps does not seem to match the information obtained from the interviews very exactly. However,

one has to take into account that land use change is a time process of years and generally not every rice

field in a neighbourhood is converted to fish pond at the same moment. This could be explained by the fact

that areas are a mix of green and white/blue colours. It could be that not all rice (or vegetable-) fields in

areas of neighbouring plots did change to fish pond on the same moment. This results in areas that are

hardly recognizable as ‘pure rice field area’ or ‘pure fish pond area’. For this reason, one has to be cautious

with interpreting the land use maps from this chapter, since the real border (or maybe a better word:

transition zone) between rice fields and fish ponds could be slightly different than on these land use maps.

Although it is difficult to make a perfect representation of the reality with remote sensed images of land

use in this area, one can still observe from the validation interviews that the rural land use is significantly

changing from rice agriculture to fish ponds. This process takes place from south to north and many people

indicate that this land use change is the result of the salinization of the water used for irrigation and the

higher frequency of crop destroying floods. According to the land use maps, the land use change is the

most significant in the neighbourhood of Pampanga River and also relatively strong around the Labangan

Channel. These waterways are both dredged years ago and canalized in order to achieve a better drainage

of the area in times of floods.

Another possibility for the land use change is the sea level rise due to climate change. Furthermore land

subsidence has to be taken into account as an influencing factor. There are estimates that the land in

Pampanga province subsides 0.5 [cm/year] inland to 8 [cm/year] at the coastal municipalities33. A last issue

that has to be taken into account is local water level rise as a result of land reclamation at the coastline of

Manila. Farmers indicate that problems in the area appeared after these land reclamations were

performed. However there are no objective researches about this available. Further research to the causes

of land use change in the project area falls outside the scope of this project.

33



Table 8-1: Land use details obtained at field interview locations

Location Current dominating land use

Former dominating land use

Time of significant land use change

Calumpit - Hagonoy

601 rice rice -

602 rice rice -

603 rice (3 harvests/year) rice (1 harvest/year) 4 years ago (2009)

604 rice + fish pond rice 15 years ago (1998)

605 fish pond fish pond -

606 fish pond rice 13 years ago (2000)


608 fish pond rice (+some fish pond) 20/30 years ago (1993/1983)


610 fish pond rice 20/25 years ago (1993/1988)

611 fish pond fish pond fish pond since 1973

612 fish pond fish pond -

Calumpit - Paombong 701

rice (2 harvests/year) + vegetable rice + vegetable -

702 rice rice -

703

rice (in rainy season only one a year) + vegetable + peanut

rice (multiple times a year) 1991

704 blue grass + vegetable rice and sugar cane 5/6 years ago (2008/2007)

705 fish pond + vegetable rice 1990-1999

706 fish pond rice "long time ago "

707 rice fish pond early 90s (1990)

708

single rice field between many fish ponds fish pond ?

709 fish pond rice late 80s begin 90s (1990)


711 fish pond mangrove 30 years ago (1983)

Malolos - Hagonoy

344 fish pond rice 2000


346 no agriculture no agriculture -

347 fish pond ? ?


349 fish pond rice 8/10 years ago (2006/2004)

350 fish pond ? ?

351 rice + fish pond rice 10/15 years ago (2004/1999)

352 rice + fish pond rice 10 years ago (2004)


9 Flood Resilient Sanitation

Residents of the delta can manage to bring themselves and each other to relative safety. Over the past ten

years, there has hardly been any casualty that was directly caused by flooding. Public health however, is

affected by the floods. Medical surveys during floods indicate the occurrence of water borne diseases.

First, the current situation of the public health and the sanitation will be discussed based on interviews and

health statistics. Second, an alternative sanitation system is presented, both for drinking water and

wastewater treatment.

9.1 Current situation Sanitation and public hygiene, related to drinking- and waste water, are of vital importance to public

health. Researches performed here, are based on information and data from the Hagonoy Water District,

the sanitation office of the municipality of Hagonoy and interviews and observations in Hagonoy and the

surrounding municipalities.

9.1.1 Public health

Ahern et Al. (2005) have made an overview of the impacts of flood on public health. Their results are

summarised below in Table 9-1.

Table 9-1: Global Health Impacts of Flooding based on Ahern et Al. (2005).

Type Specific disease Comment

Mortality Drowning/trauma Mostly during flash-floods

Yearly increase of deaths Weakened Immune system

Injuries Sprains/strains 34% of all injuries

Lacerations 24% of all injuries

“other injuries” 11% of all injuries

Abrasions/contusions 11% of all injuries

Fecal-oral disease Cholera

Cryptosporidiosis

Diarrhoea (non specific)

Acute Respiratory Infection

poliomyelitis

Rotavirus

Typhoid & Paratyphoid

Vector-borne disease Malaria

Rodent-borne disease Hantavirus

Leptospirosis Via urine from animals

Dengue

Mental health Anxiety/depression Post-flooding

Posttraumatic stress disorder Only studies from Europe and North America

Suicide Evidence from one study in a periodically flooded area

The provincial data of the Field Health Service Information System (FHSIS) have listed the top ten leading

causes of morbidity. Table 9-2 gives an overview of the most common diseases in Bulacan Province.

Looking at the data, it seems that the way the data has been collected and arranged makes a statistical

analysis impossible: e.g. Acute Respiratory Infections haven’t been mentioned in 2004 and 2005, while in

later years this was the most common in the morbidity statistics. Yet, it gives a good idea of the most

common diseases.


Waterborne diseases in Table 9-2 are acute respiratory infections, diarrhoea and typhoid. Related to water

and flooding are hypertension, urinary tract infections, infected wounds, skin diseases and dengue (via

mosquitos).

Table 9-2: Ten Leading Causes of Morbidity in Bulacan Province (all ages) between 2004 and 2009 (rate/100,000persons). Diseases related to flooding by Ahern et Al. (2005) are coloured dark blue, other waterborne or related diseases are coloured light blue. Source: FHSIS

Disease 2009 2008 2007 2006 2005 2004

Acute Respiratory Infection 8413 6331 1894 1693

Diarrhoea 757 739 804 907 754 1077

Bronchitis 305 484 396 404 388 608

Dis. Of the Heart 958 581 151 533 125

Influenza 193 446 144 700 268 206

Pneumonias 170 363 369 343 543

Hypertension 897 501

Urinary Tract Infection 510 417 81 98

Infected Wound 494 347 97

Skin Diseases 414 269

TB 138 95 72 108

Arthritis 192 194

Dog Bites 194 66

Ageing 196

Chicken Pox 17 29

Dengue 16 12

Measles 6 13

Typhoid 8

Malignant Neoplasm 1.25

More directly related to flooding are the statistics from the evacuation centres in Hagonoy in Table 9-3. A

relatively large fraction of the children, disabled, ill and old are moved to evacuation centres. Therefore,

other diseases like muscular skeletal diseases are also present in a high number. Medicine is also

distributed at the evacuation centres. Not only for flood related diseases, but also for diseases like

diabetes.

Table 9-3: Diseases in the evacuation centres of Hagonoy on 16-8-2012. Diseases related to flooding by Ahern et Al. (2005) are coloured dark blue, other waterborne or related diseases are coloured light blue. Source: statistics municipality Hagonoy

Disease Cases Disease Cases Disease Cases

Acute repiratory infection 485 Bronchial Asthma 18 Gastritis 5

Atletes Foot 193 Hypersensitivity 12 Cancer 2

Fever 89 Dental Caries 10 urinary Tract Infection 2

Hypertension 59 Otitis Media 8 Pyoderma 2

well 54 Leptospirosis 8 B. Febrile Convulsion 2

Muscular Skeletal Dis. 45 Acute Tonsillo Pharyngitis 8 Diabetes Melitus 5

Skin infection 45 Carbuncle 7 Scabies 2

Pneumonia 34 Urinary Tract Infection 6 Epilepsy 2

Diarrhea 54 Inbertigo 4 Eczema 2

Infected Wound 22 (P)TB 4 Osteoarthritis 1

Migraine 17 Sore eyes 4 Diaper Rash 2

The statistics are useful for analysing the types of diseases in the area during floods and in general.

Especially the high amounts of diarrhoea and infections indicate poor hygienic conditions, both during


periods with floods and periods without floods. Poor hygienic conditions can also make the population

more vulnerable to all kinds of other diseases.

There is a national vaccination program that provides vaccines for free, when visiting families. Therefore,

almost the whole population is vaccinated. Of the diseases in Table 9-4 there are only two that can be

directly linked to water: Hepatitis B and Rotavirus, which is a common cause of diarrhoea among young

children.

Table 9-4: Vaccines of the vaccination program34

Vaccine Protection against: Waterborne

BCG Tuberculosis No

DTwP Diphtheria No

Pertussis No

Tetanus No

PCV Streptococcus pneumoniae No

Hepatitis B vaccine Hepatitis B Yes

HiB Haemophilus influenzae No

Measles vaccine Measles No

MMR Measles No

Mumps No

Rubella (German Measles) No

OPV Poliomyelitis (Polio) Yes

RV Rotavirus Yes

9.1.2 Water supply

The water company of Hagonoy – Hagonoy Water District or HWD – supplies water in the municipality of

Hagonoy and two barangays in Paombong: San Isidro and Santo Rosario. When the current water supply

system – consisting of wells, pipes and a water tower – was constructed, it was used as drinking water

source by the residents. None of the visited families in Hagonoy did drink water directly from the tap. Most

buy water in blue jerry-cans, and some boil the water first before drinking it. In 2011, the water price for

households was 115 [PhP] for the first [m3], and 12-15 [PhP] for the next [m3]. Companies pay double that

price. Because the HWD can generate their own income, it has funds available for maintenance and even

sanitation projects.

Water from the network is also used for washing. Most families use a bucket to scoop the water when

washing themselves. Because the bucket under the tap is continuously filled with water, locals can get a

good indication of the water quality by looking at the sludge formation in the bucket. Residents from

Hagonoy mentioned that nowadays the water from the water supply becomes slimy and leaves dark stains,

most likely from sulphur.

Water abstracted by the wells is only chlorinated before it enters the network. The wells are located in

between the houses. A problem indicated by the HWD is leaking of polluted water from the septic tanks in

the town and into the water taken up by the wells. Currently, the water tests all indicate a good water

quality, both in coliform count and in chemicals.

The main network lies under the streets, with the private connections sticking out on the sides of the

streets with the meters. When the roads are raised, the network becomes more and more inaccessible.

There are no private wells in Hagonoy, or at least they are not visible, because they are illegal. In the rural

areas of Paombong nearly all farms have a private well and a connection to the water supply network.

34

Philippine Foundation for Vaccination (2013)


During the round of interviews and visiting families, some water samples have been taken from the tap.

The salinity, oxygen concentration and pH-value have been measured and are given in Table 9-5. The

samples have been taken all over Hagonoy, yet there is no clear variation noticeable in salinity

concentrations. Even the communities close to Manila Bay have a salinity that is comparable to the rest of

Hagonoy. The oxygen concentrations indicate that the aquifer from where the water is abstracted is

unconfined, and more susceptible to pollution.

Table 9-5: Measured concentrations of salinity, oxygen and pH in the tap water in Hagonoy. One manual private well has been found and tested and the fishermen communities Tibaguin, Masukol and Pugad near Manila bay were also visited. *aerated while taking the sample

House Salinity (mg/l) O2 mg/l pH

1 0.3 2.00 7.9

2 0.3 2.00 7.5

3 0.3 0.96 7.8

4 0.4 1.15 7.6

5 0.2 4.20* 7.7

6 0.3 1.10 7.7

7 0.2 3.50* 7.6

8 0.3 1.04 7.6

Manual well 0.6 1.85 7.8

Tibaguin 0.3 1.56 7.8

Masukol (Paombong) 0.2 2.14 7.7

Pugad 0.2 1.57 7.9

9.1.3 Drinking water

Potent water is distributed in blue jerry cans by private companies. They deliver water with tricycles to

customers who have texted them. Shops also sell blue jerry-cans, sometimes with a small discount. Some

shops however, are not trusted by the companies, as they refill the jerry-cans themselves with network

water. To prevent fraud, the supplier of the empty jerry-cans also provides seals for the top caps and the

tap.

Blue jerry-cans are a good way of drinking water distribution during floods. If the treatment facilities are

under water and they cannot be used, jerry-cans from other areas can be imported as the infrastructure of

the jerry-cans is already there.

Prizes range between 20 [PhP] and 30 [PhP] per jerry-can of 20 litres – 1,000 and 1,500 [PHP] per [m3]

respectively – which is 100 times more expensive than tap water. Therefore, it is only used by some for

cooking as well. The source of water is either a private well, though it is illegal, or water from the network

for which they have to pay double the amount.

Each treatment facility uses different modules for treating the water. Treatment steps used are mainly

filters, ranging from microfiltration to reverse osmosis (RO). Which membrane filters are used is hard to

tell. RO however was quite easy to observe as afterwards some nutrients had to be added. Other

treatment technologies used are ion exchange, activated carbon, UV (ultra violet light) and granular

filtration. The companies say they are checked every month by Aqualab, of the Department of Health.


Figure 9-1: Typical treatment steps used for drinking water treatment in Hagonoy

The filters and reactors are sold by companies all over the Philippines. Which treatment step is applied

widely varies. There are companies that only use a membrane filter, but most have quite an extensive

process. Those without ion exchange and reverse osmosis can hardly remove heavy metals or nutrients

from the water. However, the oxygen concentration in the water and the analysis by the HWD suggest that

there is no need for heavy metal removal. Water comes in contact with the air only at the moment the blue

jerry-cans are filled: aeration is not part of the treatment process. The water price does not seem to

depend on the extensiveness of the treatment.

9.1.4 Wastewater

Hagonoy does not have a central sewerage system. Instead, households discharge their grey water – grey

water contains water used for washing and cooking – directly onto the surface water or into the drainage

canals. The black water – water from toilets – flows either to a septic tank or is discharged onto the surface

water as well. In 2011, 67% of the households had a septic tank35. Most of these septic tanks leak into the

ground, and are not emptied because of the costs. Only 48% of the septic tanks is accessible for

maintenance35. Some septic tanks are private, and some are used by multiple households. Those without

toilet facilities use either the toilet of neighbouring relatives or collect it in a bucket and throw it into the

river. The data of the municipal sanitary officer show that in the year 2013 2% of the households did not

have a toilet.

The sanitation officer inspects the toilets in Hagonoy for hygiene. He also inspects locations with

complaints about hygiene or businesses like life stock farms, which decrease the water quality. The

agricultural water system for the fishponds, rice fields etc. is not separated from the urban water system.

Without proper sanitation of both the farms and the households, contamination from animal manure or

human waste is very likely.

During floods, toilets on the first floor are inaccessible or at least do not work. Those staying behind simply

dump their waste directly onto the surface water. Another problem related to flooding are the mixing of

surface water with water from the septic tanks.

35

Hagonoy Water District (2011)


9.2 Improving the sanitary conditions

To prepare the sanitary conditions for the next decades, some improvements have to be made. The HWD

already has some ideas to improve both the (drinking) water supply and the wastewater treatment. Their

plans are discussed together with some alternatives. They are also analysed for their flood resiliency.

9.2.1 Drinking water

If the HWD wants to discourage private wells for the production of drinking water by private companies,

they might have to reduce the water price for these companies. Also, safe drinking water is a commodity

that should be accessible to all. Cooperating with the companies providing the drinking water is essential

for that.

Moving to a different source of water is beneficial for the water quality. The current system is too

vulnerable for source contamination. Essentially, there are two sources available: surface water and

groundwater.

Surface water in general has a poorer quality and has higher quality and quantity fluctuations than

groundwater. Surface water needs extensive filtration, especially in the Philippines since monsoon rains

can cause high turbid water. A solution can be riverbank filtration, where water from the river first passes

about 30 meters of soil before it reaches the well. After that, aeration, filtration and disinfection steps have

to be applied.

Surface water is not only vulnerable to seasonal fluctuations, but also to climatic changes. Lower discharges

in dry periods will increase the saltwater intrusion in both the Angat River and the Pampanga River. It is

very costly to remove salt from drinking water. With possible increasing salt intrusion, building a large and

expensive drinking water treatment facility will be the wrong choice.

An alternative is groundwater, but abstracted from a different area away from the densely populated town.

A groundwater model should give information on whether the recharge of the aquifer is sufficient.

Otherwise, artificial recharge can be an option. This does not necessarily require wells pumping water into

the aquifer. In some places, the top clay layer can be substituted with more porous materials to improve

the speed of infiltration of rainwater in the wet season.

The quality of the source water is vital: the better the quality is before the treatment, the less extensive,

expensive and vulnerable the water supply is. Source protection is therefore crucial. Industries, life stock

and other polluting activities should be banned at the infiltration zone and the surroundings.

When treating groundwater, aeration is important to remove heavy metals and substances that cause

odour and smell like hydrogen sulphide and ammonia. After aeration, the water should go through a dry

filter – with either sand or activated carbon as filter material – to capture the heavy metals and for

biological breakdown of nutrients. Disinfection can be applied after the filter, with ultra-violet light (UV-

disinfection) and post chlorination before it enters the network. UV-disinfection is cheap and very effective

against all pathogens, unlike chlorine. Extra aeration and an activated carbon filter are optional. The

treatment scheme is shown below in Figure 9-2.


Figure 9-2: Proposed treatment scheme for treatment of infiltrated groundwater

9.2.2 “Waste”water

Currently, there are plans made for construction of septic tanks with two chambers of which the effluent

discharges onto the drainage channels on the sides of the road. The septic tanks will be made accessible36.

For most, the construction of such septic tanks is unaffordable or they prefer to spend their money on

something else. A possibility is investment in communal septic tanks, maintained by the HWD. The septic

tanks should be resilient to flooding. This can be achieved by blocking the overflow and the pipe connecting

the toilets during floods.

Excess sludge from the septic tanks should be removed every couple of years. This is only possible when

the septic tanks are easily accessible. A truck was proposed for the removal of the excess sludge from the

septic tanks which brings it to a treatment facility36.

An alternative for this treatment is a more resource oriented approach. Black water is rich in nutrients and

energy. When urine and faeces are split at the toilet, the nutrient rich urine and energy rich faeces can be

made profitable. Urine is sterile, and rich in phosphorous. It can therefore be the raw material for the

production of fertiliser, which on its turn can be used in agriculture and for the production of algae for

fishponds.

The urine and faeces can be collected in containers an put on the sides of the road. This requires fewer

investments compared to the septic tanks, and is therefore within reach of the whole population. It is also

more flood resilient, as the same system of collection and treatment can continue during floods. Each

participating household can get a discount on their water bill if they participate in the project.

The energy potential of faeces can be turned into CH4 gas via anaerobic treatment. This is the advantage of

anaerobic treatment in comparison with aerobic treatment: anaerobic treatment produces energy in the

form of bio-gas and produces less excess sludge while aerobic treatment consumes a lot of energy for

aeration and creates a lot of excess sludge.37

36

Hagonoy Water District (2011) 37

Metcalf & Eddy (2014)


Figure 9-3: Resource oriented sanitation by splitting urine and faeces

Splitting urine from the faeces is beneficial for the production of methane gas in the anaerobic reactor, but

it is not necessary. Anaerobic treatment is also possible for the system of collection of excess sludge from

the septic tanks. However, it will produce less bio-gas as part of the energy has already dissipated in the

septic tanks. Anaerobic reactors do not require a continuous process and can quickly respond after long

periods without feed. They are therefore more suitable for treating batches of wastewater than aerobic

reactors. However, anaerobic reactors are more sensitive to the composition of the wastewater.37

Toilet

Urine Fertilizer

Agriculture

Algae production

Faeces Biogas (CH4)

Fuel

Electricity


10 The Framework for Vulnerability

The following descriptions of vulnerability are based on the article Alternative water management options

to reduce vulnerability for climate change in the Netherlands by De Graaf, Van de Giesen and Van de Ven

(2007). Although it has been developed for the Netherlands, it is a good framework to look at the

vulnerability of the delta of the Pampanga and Angat. The general theory of the framework will be

explained first, after which the theory will be applied on the local situation of the delta.

10.1 What is vulnerability?

Vulnerability can be described as “the ability to build a threshold against disturbances”38. A low

vulnerability is vital for economic development. Figure 10-1 shows a scheme which describes the aspects of

a system in relation to its vulnerability. The explanation of the vulnerability scheme is based on the lectures

of Frans van de Ven (2012).

Figure 10-1: Effects of the system – with pressures, thresholds, sensitivities and adaptabilities – on the vulnerability (based on the lecture slides of Van de Ven, 2013)

A company that wants to expand its business looks for the most suitable area to invest in. This can depend

on the skill of the local workforce, the company’s origin but also the vulnerability of an area in relation to

natural hazards like flooding. Banks do the same thing when they grand credit to a business.

The hazards are part of the pressures. Examples of pressures are rainfall, discharges, tides, wind etc. The

chance of occurrence depends on the size of a particular pressure: the larger the size of the pressure, the

lower the chance of occurrence.

Whether a system fails at a certain size of the pressure depends on the level of the threshold: only when

the pressure exceeds the threshold level, the system fails. Examples of thresholds are dikes, hydraulic

structures, discharge capacities and land levels. One can imagine that a system with raised dikes and

increased discharge capacities of the rivers and streams has a lower chance of failure. The Netherlands

uses dike-ring systems. Within a dike ring system the chances of failure are equal, because the thresholds

38

De Graaf, Van de Giesen and Van de Ven (2007)


of which the dike ring consists are adjusted to the local pressures. The chances of exceeding lie between

once per 250 years and once per 10,000 years.

The chance of failure varies over an area. When mapping the chance of failure, this will result in a hazard

map.

Take into account that we are talking about chances of failure. This means that no threshold can ever

prevent that a system will fail. It can only reduce the chance of failure. When looking at vulnerability, we

should also think of what will happen when the system fails.

The company however, will not only look at the chance of failure, but also at the effects a hazard will have

on its business. In other words, the company will look at its risk. The risk depends on the chance of failure

and the damage sensitivity of the business to the hazard.

The damage sensitivity depends on the type of business and its dependency on the environment. How well

can the business cope with a hazard and how well can it recover? For example a farm can reduce its

damage sensitivity by growing alternative crops. A business can arrange its building in such a way that the

most vital things are the safest. This will make that the farm or the business can better cope with or more

easily recover from the hazard. The reason the roads in the delta are elevated is also because of the

damage sensitivity: they are vital for the infrastructure. The local and regional economies rely on these

roads. The damage sensitivity cannot be reduced, and therefore the threshold is increased by raising the

road.

The risk can also be mapped, by taking into account the sensitivity of the activities in the area. The result is

a risk map.

The vulnerability depends on the risk and the adaptability. A wooden shed is more adaptable than a

concrete building. The previous example of a farm being able to grow alternative crops is also an example

of adaptability.

There are four capacities which can be adjusted to decrease the vulnerability: Threshold capacity, coping

capacity, recovery capacity and adaptive capacity39.

10.2 Theory of the vulnerability framework To assess the vulnerability of an area or system, it is split up into four capacities, following the theories of

De Graaf, Van de Giesen and Van de Ven (2007). The vulnerability framework can, besides flooding, also be

used for water quality and resources e.g. water supply.

Threshold capacity describes the ability of a society to prevent damage. Examples related to flooding are

dikes, discharge capacities etc. An example related to water supply is the construction of reservoirs to

reduce the effects of drought.

Coping capacity describes the ability to reduce the damage in case the threshold is exceeded. In relation to

flooding, this capacity can consist of emergency and evacuation plans, damage reducing measures,

creation of risk awareness and a clear organisational structure. Examples for water supply are emergency

39

De Graaf, Van de Giesen and Van de Ven (2007)


and backup water facilities and a distribution plan in case of drought. Coping capacity reduces the damage

during a hazard, because of earlier construction and organisation.

Recovery capacity is the ability of a society to recover to an equivalent state as before the hazard. Examples

for after flooding are the reconstruction of infrastructure, buildings, dikes etc. For water supply, one can

think of cleaning or rebuilding the distribution and drainage system and re-achieving safe supply and

sanitation. Also, the economic capacity and the political will and organisation to recover are part of this

capacity.

Adaptive capacity is the ability to adapt and adjust to future uncertainties. This requires a vision or a

prediction of future circumstances that can outbalance a currently good functioning system. Examples of

these circumstances are climate change, population growth and changes in land use.

This capacity is determined by the will of the residents and other actors to allow implementation of

solutions or to implement solutions themselves, the knowledge and perception of water related problems

and the contribution to it of the residents and decision makers, the locally available solutions and

resources, property rights (social capital) and the presence of relevant institutions.

10.3 Capacities in the Manila Bay Delta

The assessment of each capacity is based on the observations during the fieldwork and the interviews in

Hagonoy. Each capacity is discussed separately.

10.3.1 Threshold capacity

Increasing the threshold capacity in the delta is more an individual action than a community action:

Farmers and fishpond farmers raise their levies, businesses and houses are built artificial hills, about 1.5-2

meters higher than the surrounding and doorsteps are raised – some doorsteps are more than two feet

high.

Whether a farm, household of business can increase the threshold capacity depends on their financial

strength. Most large houses in the south of Hagonoy are owned by large fishpond owners. These houses all

have a raised ground level. These households stay close to their businesses in the south of Hagonoy. Other

more wealthy families have already moved to higher grounds in the surrounding. This clearly has had an

impact on the distribution of the living conditions: poor living conditions and more densely populated

neighbourhoods in the south compared to the north.

Different government levels also work individually: raising the roads only reduces the flooding of the roads,

but increases the flooding of the other areas according to the locals – especially the areas between the

elevated road and the river in Hagonoy. Riverbanks are also the responsibility of the land owners on the

shore. In fact, the whole river management and maintenance is not organized: the Labangan channel

hasn’t been dredged since the construction of the Labangan Channel in the ’70 and are all filled with

garbage and litter.

On the sides of the Pampanga estuary channel lay two dikes that should protect the surrounding area

during high water levels, as can be seen in Figure 10-2. However, the dikes do not form a ring, and water

can flow through the gaps in between. The offtake of the Hagonoy River is also a gap in the dike ring: there

are no dikes on the sides of the Hagonoy River and there is no hydraulic structure regulating the discharge

at the offtake.


West of the mouth of the Pampanga, the land subsidence is between 2 to 8 [cm/year]40. Some residents

and officials also indicate that land subsidence is a big problem and the cause of the increase in tidal floods

over the past years. Others however, refer to climate change and sea level rise cause. The result is an

increase in the chance or occurrence of tidal flooding, whether it is the decrease of the threshold level or

the increase in pressure.

Figure 10-2: The dikes on the side of the Pampanga estuary (marked red) stop at one point. There are smaller dikes that lie closer to the river up to the start of the Hagonoy River (marked blue). There are no hydraulic structures to regulate the flow into the Hagonoy River from the Pampanga. (Images/maps: Google, Cnes/Spot Image, DigitalGlobe, Landsat, 2014)

10.3.2 Coping capacity

Every governmental level has a disaster management council. Their coping plans are based on their own

experiences in the municipality. The MDRRMC (Municipal Disaster Risk Reduction Management Council)

operates at the municipal level. For tidal flooding, which mainly affects the southern barangays of

Hagonoy, there is a tidal calendar. Residents can plan their activities with the tidal calendar. In some places

the tidal floods have become so severe, that families have abandoned their houses, or their first floor.

The upstream flooding mainly affects the north of Hagonoy, both in duration and in water level. The

MDRRMC monitors the chances of flooding, helps with public relief and evacuation during the floods and

helps with the recovery after the flood. The organisational chart is given below in Figure 10-3.

40



Figure 10-3: The organisation of the Hagonoy MDRRMC as of September 2012.

The command centre or “the body of the crab” (coloured red in Figure 10-3) consists of the chairman – the

mayor – the action officers who coordinate the operations and the flood monitoring officer, who is in

contact with the flood forecasting centres of the Pampanga and Angat and the provincial disaster risk

management. They will provide information on the state of the water levels – e.g.

normal/critical/decreasing – or on the dam releases. On its turn, the MDRRMC warns the residents of a

coming flood. In practice, all know what can happen during the raining season. After watching the weather

forecast in the upstream areas, residents have often already predicted the floods themselves.

Below the command centre is the layer that manages the practical aspects during the flood (coloured

green in Figure 10-3). Communication within the MDRRMC is done by the action officer. The action officer

is also part of the call centre or communication and media relations team. They also keep in touch with

family members abroad – almost every family has a relative working outside the Philippines – and partially

rely on them financially – and communicate with the barangay disaster risk reduction and management

council or BDRRMC. Communication can be difficult as mobile phone network is sometimes out of

operation during floods.

During a flood there are about 100-300 volunteers active. These are all managed by the personnel officer.

The finances for the operation and preparation, buying food and other relief goods and paying some of the

volunteers, are done by the finances officer. The logistics team has to distribute both the volunteers and

their food over the municipality. They also provide the teams with equipment when necessary.

The operation in the field is done by the teams that are coloured blue in Figure 10-3. The rescue operations

team consists of trained residents, which can evacuate elders, children, disabled or ill and take them to an

evacuation centre or the hospital.

In practice, most households have at least one member staying behind during a flood, while the children

and elder go to the evacuation centre or to relatives. Some go to their neighbours or family, if they have a

good relationship and a 2nd floor. Relief operations provide food and drinking water to those in need. The

municipality has a stock of food prepared for times of flood. A large number of residents in Hagonoy are

day labourers, like tricycle drivers, who spend what they have earned on the same day. Stores are either


closed or have become very expensive during floods. Those without savings therefore depend on the relief

operations team.

Evacuation centres provide refuge for those living in the neighbourhood. Most evacuation centres are

schools and covered basketball courts. The evacuation centre management is in charge of the centre and

keeps an eye on those staying there, which is necessary when a large number of people of people are living

close together under such stressful circumstances. Figure 10-4 gives a good idea of the situation in an

evacuation centre.

The medical operations team is also present at the evacuation centres and pays visits to those who stayed

at home. The team consists of the same municipal doctors, nurses and orderlies and volunteers who also

staff the municipal health offices. They also advise people to move to an evacuation centre or to a hospital.

The residents going to school or employed outside the municipality still have to commute during the

floods. For the lower water levels, there are elevated tricycles. These can be found especially in the south

of Hagonoy, which is affected most by the frequent tidal floods. The public transport system with busses

and jeepneys is replaced by bigger wheeled dumper trucks.

Figure 10-4: Evacuation centre in Calumpit in 201341

.

The public utilities coordination focuses on water distribution system, the electricity supply and telephone

connections. These utilities are still crucial during floods.

41

Rappler (2014)


10.3.3 Recovery capacity

The teams in Figure 10-3 that are coloured purple focus on the recovery after the flood. This involves the

damage assessment and infrastructure rehabilitation. Farmers can get some funds from the national

government for their lost crops, but these are hard to get and minor compared to the losses.

The houses in Hagonoy are also adjusted to the circumstances: there is hardly any plaster in the south on

the walls of the houses as there are a lot of tidal floods. It will simply be too costly to build a beautiful

house that should be redecorated after every tidal flood. Originally, the people in the delta lived in bamboo

houses on small poles that are easy to rebuild. Switching back to this building style is not an option.

After the floods, garbage that was taken up from the streets and from the canals has ended up on the

streets, in gardens, houses and buildings. This also requires organised communal actions, as there is

normally no garbage collection system.

Some fishponds are also adjusted to improve the coping capacity: fishponds with breached dams have

placed nets inside. An extra upside is that the fishpond is now also a buffer for collection of water. A

downside is that the waste the fish produce affects the environment.

10.3.4 Adaptive capacity

At this moment, the dikes do not provide adequate protection for the land lying behind it. Since the dikes

are currently the highest points of the area, they are the best place to build a house. When the dike system

has to be adapted to cope with changed pressures or increased standards the houses have to be removed.

This was also the reason why the dikes on the sides of the Pampanga Estuary could not be extended: the

residents on the shores of the Pampanga did not want to move away and blocked the construction of the

dike.

The same thing is true for the canals: on the inner corners where there has been enough sediment

deposited, locals have built their house. When these canals have to be adapted to increase the discharge

capacity, these houses have to be removed.

The farmers that are able to switch from rice to fishponds or to other more flood resilient crops like specific

types of grass, also made use of their adaptive capacity. However, salt water fishponds might be hard to

turn back into rice paddies.

10.4 Conclusions and recommendations

A water system that has a low vulnerability and is sustainable and resilient should not only pay attention on

high dikes and hydraulic structures. These measures are only the first step to decrease the vulnerability.

Implementing and improving these hydraulic structures increases the threshold capacity. The threshold

capacity depends on the weakest link: only when the whole system of thresholds has been well-planned

and implemented, it reduces the chance of failure. This requires involvement of representatives from all

governmental levels. The decisions should not be implemented from top down, but the higher

governmental levels should involve the municipal engineers and planners since they know their area best.

What improves the situation for one community can worsen the situation for the other. The decision of the

municipalities to work together is a good step since building threshold capacity is most efficient when done

on a large scale.

The resiliency of the local population is something to cherish: if the chances of flooding are reduced,

resiliency remains important. The municipalities seem to be well prepared for situations like flooding, and


this will still be important in the future. Of course, the physical situation as it is now is not something to

cherish.

However, not all are able to cope with the situation: some farms could not cope with or recover after the

floods. Rice fields are abandoned and the wealthy residents either move to a different location or increase

their own threshold strength by living on an artificial hill. With increased wealth the damage sensitivity also

increases.

The budget for the municipalities is too low for a good recovery capacity. The quicker the response, the

faster the situation returns to an equivalent state and the less damage will remain in the future.

The future circumstances are hard to predict. Increasing the adaptive capacity in the delta requires a long

term view and good spatial planning. For spatial planning cooperation, awareness and institutional strength

are important to prevent individuals from building on the wrong places. The hydraulic structures should

allow for adjustments in the future.

The basis for economic growth is the reduction of vulnerability. When the vulnerability of the area has

been reduced, it becomes more interesting for investments. Lying in between Clark airport in Angeles and

the capital Manila, the area has a good potential for economic development.


11 Conclusion

Serious water related problems exist in the Pampanga delta. These problems are not expected to decrease,

but rather to increase. We believe the Pampanga delta requires maintenance, restructuring or a

combination. Complete restructuring is an option which might not be economically viable.

This delta is a complicated, interconnected system. Work on the delta can be done either by local ‘trial and

error’ or by a complete system analysis. ‘Trial and error’ has most chance to result in error, as what will be

a solution for some, will result in a problem for others. Thereby, individuals have different capabilities to

implement measures. Cooperation is the key. To perform system analysis, serious investments will have to

be made by the whole community, which will not show immediate results.

Primary attention should be given to hydraulic modelling of the flooding, as the problems are of today and

ask for ad hoc measures. A simple first model setup has been made using SOBEK. The vital ingredient is a

high resolution elevation model, which was not available (to us). This is because tidal flooding is a matter of

centimetres, as the tidal range is relatively small. Profiles of the main rivers and tidal boundary conditions

of depth variation have been obtained. With these ingredients and a small river flow assumption, a virtual

reality model could be constructed in which solutions for tidal flooding can be tested.

River discharges require additional hydrological research. Rainfall measurements have been analysed, but

little effort has been made for the conversion from rain to discharge, since ground measurements are

essential. They are available in the form of seemingly reliable hourly water heights, but measurements

should be taken to convert them to river discharges. Several of these gauging stations also measure tidal

influence and therefore cannot be used to compute discharges, so it is advisable to gauge higher up in the

smaller branches of the catchment.

A secondary issue with large impact is the gradual conversion from rice fields to fish ponds. This seems to

be partially forced by flooding and salt intrusion, which can both be expected to increase in the current

state. For another part this conversion seems driven by economic interests, since the fish is economically

viable. The process can be observed by satellites, as the two land types can be distinguished quite clearly.

Flood reduction measures, like potential dredging, will significantly influence the salt intrusion and might

accelerate this process from gradual to sudden impact.

Another secondary issue is sanitation. The current source of the water supply lies within the urban area.

Groundwater abstraction from an urban area with leaking septic tanks poses possible health risks. The

uncertainties of the future quality and quantity of the surface waters make that surface water treatment is

too risky. Groundwater abstraction from a protected area might be a better option, as it requires little and

inexpensive treatment. Public health risks increase during floods because of the poor water quality.

Improving the sewage system will not only have a large effect on the quality of the surface water, but also

gives chances of resource recovery.



12 References

1. Japan International Cooperation Agency (JICA), CTI Engineering International co., LTD. & Nippon

Koei co., LTD. (2011) The study on integrated water resources management for poverty alleviation

and economic development, Volume I: Summary, National Water Resources Board, The Republic of

the Philippines.

2. The Republic of the Philippines Ministry of Public Works and Highways National Irrigation

Administration, Feasibility Report on the Pampanga Delta Development Project, Main Text,

February 1982, JICA, Tokyo, Japan

3. Savenije, H.H.G., 2007, Lecture notes CT5450 Hydrology of Catchments, Rivers and Deltas, Water

Resources Section, Delft University of Technology, Delft

4. Savenije, H.H.G., Salinity and Tides in Alluvial Estuaries, Second Completely Revised Edition, 2012;

Delft University of Technology

5. Ahern M., Kovats R.S., Wilkinson P., Few R. & Matthies F. (2005) Global Health Impacts of Floods:

Epidemiologic Evidence. Epidemiologic Reviews 27, 36-46

6. Hagonoy Water District and The Philippine Water Revolving Fund Support Program (2011)

Hagonoy, Bulacan. Septage Management Project, Feasibility Study. Proposal for USAID.

7. Van Lier J.B., Mahmoud N. & Zeeman G. (2008) Anaerobic Wastewater Treatment. Biological

Wastewater Treatment: Principles Modelling and Design. Chapter 16. IWA Publishing.

8. Van Lier J.B., Rietveld L.C., Verberk Q.J.C. & Spanjers H. (2011) Fundamentals of drinking water and

wastewater treatment. Delft University of Technology, Faculty of Civil engineering and

Geosciences, Sanitary Engineering Department.

9. Metcalf & Eddy (2014) Wastewater engineering: treatment and resource recovery. Fifth Edition. Mc

Graw Hill.

10. De Moel P.J., Verberk J.Q.J.C. & van Dijk J.C. (2006). Drinking water- Principles and practices. World

Scientific

11. Shimi A.C., Parvin G.A., Biswas C. & Shaw R. (2010) Impact and adaptation to flood, a focus on

water supply, sanitation and health problems of rural community in Banladesh. Disaster Prevention

and Management 19, 298-313

12. Verberk J.Q.J.C., Van der Meer W.G.J., Van der Hoek J.P., Heijman S.G.J., De Ridder D. , Grefte A., P.

Andeweg (2011) Drinking water treatment. Delft University of Technology, Faculty of Civil

engineering and Geosciences, Sanitary Engineering Department.

13. WHO (2011). Guidelines for Drinking- water Quality. Fourth Edition .World Health Organization

Press, Geneva.

14. De Graaf R., Van de Giesen N. & Van de Ven F. (2009) Alternative water management options to

reduce vulnearbility for climate change in the Netherlands. Nat. Hazards 51, 407-422

15. Van de Ven F. (2013) Lecture slides Water Management in Urban Areas. Delft University of

Technology, Faculty of Civil engineering and Geosciences, Section of Water Resources

Management.

16. Provincial Planning and Development Office (August, 2009); Province of Bulacan - Provincial

Development and Physical Framework Plan - Flooding Map; DENR – Mines and Geosciences Bureau

17. Philippine Atmospheric, Geophysical & Astronomical Services Administration (PAGASA, 2013)

http://www.pagasa.dost.gov.ph/, Applied on March 28, 2014


18. Philippine Statistics Authority – National Statistical Coordination Board; (June, 2013)

http://www.nscb.gov.ph/activestats/psgc/NSCB_PSGC_SUMMARY_2013Jun30.pdf , Applied on

March 28, 2014

19. Alliance for coastal technologies (2013);

http://www.act-us.info/sensor_list.php?cat=Groundwater&type=Physical , Applied on March 28,

2014

20. PRFFWC (2013); http://prffwc.webs.com/, Applied on March 28, 2014

21. Deltares (2013); http://www.deltares.nl/nl/software/108282/sobek-suite , Applied on March 28,

2014

22. QGIS (2014); http://www.qgis.nl/, Applied on March 28, 2014

23. Google Earth (2014)

24. United States Geographical Survey (USGS, 2013); http://www.usgs.gov/, Applied on March 28,

2014

25. NASA (2014); http://www2.jpl.nasa.gov/srtm/, Applied on March 28, 2014

26. Nationwide Operational Assessment of Hazards (NOAH, 2014); http://noah.dost.gov.ph/, Applied

on March 28, 2014

27. Rappler (2014); www.rappler.com , Applied on March 28, 2014

28. Philippine Foundation for Vaccination (2013); www.philvaccin.org, Applied on March 28, 2014

29. Inquirer; Mapping flood hazards goes high tech; Inquirer.net (December, 2012), Applied on March

28, 2014


13 Appendices

– Spatial scope of work Appendix 1

On the following map the eight coastal municipalities of the alliance are indicated.

Figure 13-1: Map of coastal municipalities in alliance



– Flooding map Appendix 2 This flooding map42 is obtained from the Provincial Planning and Development Office (August, 2009) and

roughly visualises extreme flooding heights in the Pampanga delta.

Figure 13-2: Flooding map Bulacan Province

42

Provincial Planning and Development Office (August, 2009)



– Tidal curves in Manila Bay43 Appendix 3

This map of the PRFFWC is used as comparison to the findings of this project.

Figure 13-3: Tide curves for reference stations

43

PRFFWC



– Pressure changes and tidal ranges in Pampanga mouth and Sulipan Appendix 4

2014/01/05-2014/01/21

Here, the obtained absolute water pressure changes in the Pampanga River during the given period are

shown. See Excel-file for values.

Unfortunately, this appendix is not publicly available. For more information on these


Figure 13-4: Tidal ranges obtained from diver measurements



– Pressure changes during measuring interval in Pampanga mouth and Appendix 5

Sulipan 2014/01/06

Here, the obtained absolute water pressure changes in the Pampanga River in the 3-hour measuring

interval are shown. See Excel-file for values.



Figure 13-5: Tidal influence on depth measuring interval



– Measurements in Pampanga mouth and Sulipan 2014/01/06 Appendix 6



Figure 13-6: Measurements in Pampana mouth and Sulipan



– Depth measurements in Pampanga 2014/01/06 Appendix 7 See graph below for the measured depths and calculated flow profiles of the Pampanga River. See Excel-file

for values.



Figure 13-7: Depths Pampanga River

Figure 13-8: Flow profile areas Pampanga River



– Width variations in Pampanga Appendix 8 See graph below for the calculated width variations of the rivers Pampanga and Angat. See Excel-file for

values.



Figure 13-9: Width variations Pampanga River



– Table of depth measurements in Angat 2014/01/07, not corrected for Appendix 9

tide



Figure 13-10: Depth measurements in Angat River



– Profile measurements in Angat 2014/01/07, not corrected for tide Appendix 10 See graphs below for the measured depths and calculated flow profiles of the Angat River. See Excel-file for

values.



Figure 13-11: Depths Angat River

Figure 13-12: Flow profile areas Angat River



– Depth measurements in Calumpit 2014/01/09, not corrected for tide Appendix 11



Figure 13-13: Depth measurements in Calumpit



– Depth measurements in Calumpit2014/01/09, not corrected for tide Appendix 12 See graphs below for the measured depths of the connection between the rivers Pampanga and Angat. See

Excel-file for values.



Figure 13-14: Depths Pampanga (Calumpit)

Figure 13-15: Depths Calumpit South

Figure 13-16: Depths Calumpit North-East

Figure 13-17: Depths Calumpit to Angat

Figure 13-18: Depths Angat (Calumpit)



– Cross sections Hagonoy River, tidal influence slightly visible Appendix 13

See graphs below for the tape-measured depths of the Hagonoy River. See Excel-file for values.



Figure 13-19: Depths Hagonoy River (B022)





– Average depths Pampanga and Angat Appendix 14

See QGIS-map 44 below for the calculated average depths per profile during the measuring interval.



Figure 13-22: Average depths River system (Images/maps: Google, TerraMetrics, 2014)

44

Tool: QGIS



– Hydrodynamic modelling Appendix 15 This appendix shows images which further clarify the inputs and outcomes of the hydrodynamic modelling

process45.

Figure 13-23: SOBEK 1D model on GIS layer (Deltares)

45

SOBEK


Figure 13-24: DEM Pampanga River Basin with 1D model in the Pampanga Delta (Deltares)

Figure 13-25: Legend SOBEK 2D model (units: [m])


– IDF curves rainfall stations Pampanga River Basin Appendix 16

In this appendix, the intensity-duration-frequency curves of ten rainfall stations are given. The information

is based on rainfall data acquired from 1974 until 2008. On average, 13% of the rainfall data is missing over

this period for the ten stations.

Figure 13-26: IDF curves Sapang Buho

Figure 13-27: IDF curves Zaragoza

0

50

100

150

200

250

300

350

0 2 4 6 8 10 12

Rai

nfa

ll in

ten

sity

(m

m/d

)

Duration (days)

Intensity-Duration-Frequency curves Sapang Buho

T=2

T=5

T=10

T=20

T=50

T=100

0

50

100

150

200

250

300

0 2 4 6 8 10 12

Rai

nfa

ll in

ten

sity

(m

m/d

)

Duration (days)


T=2

T=5

T=10

T=20

T=50

T=100


Figure 13-28: IDF curves Papaya

Figure 13-29: IDF curves San Isidro

0

50

100

150

200

250

300

350

400

0 2 4 6 8 10 12

Rai

nfa

ll in

ten

sity

(m

m/d

)

Duration (days)

Intensity-Duration-Frequency curves Papaya

T=2

T=5

T=10

T=20

T=50

T=100

0

50

100

150

200

250

300

0 2 4 6 8 10 12

Rai

nfa

ll in

ten

sity

(m

m/d

)

Duration (days)

Intensity-Duration-Frequency curves San Isidro

T=2

T=5

T=10

T=20

T=50

T=100


Figure 13-30: IDF curves Arayat

Figure 13-31: IDF curves Candaba

0

50

100

150

200

250

300

0 2 4 6 8 10 12

Rai

nfa

ll in

ten

sity

(m

m/d

)

Duration (days)

Intensity-Duration-Frequency curves Arayat

T=2

T=5

T=10

T=20

T=50

T=100

0

50

100

150

200

250

300

350

0 2 4 6 8 10 12

Rai

nfa

ll in

ten

sity

(m

m/d

)

Duration (days)

Intensity-Duration-Frequency curves Candaba

T=2

T=5

T=10

T=20

T=50

T=100


Figure 13-32: IDF curves Sibul Spring

Figure 13-33: IDF curves Sulipan

0

50

100

150

200

250

300

350

400

0 2 4 6 8 10 12

Rai

nfa

ll in

ten

sity

(m

m/d

)

Duration (days)

Intensity-Duration-Frequency curves Sibul Spring

T=2

T=5

T=10

T=20

T=50

T=100

0

50

100

150

200

250

300

350

0 2 4 6 8 10 12

Rai

nfa

ll in

ten

sity

(m

m/d

)

Duration (days)

Intensity-Duration-Frequency curves Sulipan

T=2

T=5

T=10

T=20

T=50

T=100


Figure 13-34: IDF curves Ipo Dam

Figure 13-35: IDF curves San Rafael

0

100

200

300

400

500

0 2 4 6 8 10 12

Rai

nfa

ll in

ten

sity

(m

m/d

)

Duration (days)

Intensity-Duration-Frequency curves Ipo Dam

T=2

T=5

T=10

T=20

T=50

T=100

0

50

100

150

200

250

300

350

0 2 4 6 8 10 12

Rai

nfa

ll in

ten

sity

(m

m/d

)

Duration (days)

Intensity-Duration-Frequency curves San Rafael

T=2

T=5

T=10

T=20

T=50

T=100



– Salt intrusion Appendix 17

Phase lag equation:

( )

( )

=7.0282e-05

c=6.25

b=65000

=0

Geometry tide relation:

( )

=4

=1

H=1.25



– Fish ponds in project area Appendix 18 The figure below is an overview of the fish ponds in the project area of eight municipalities. Fish ponds in

the south-east are not shown. This due to the fact that there only information in shape files was available

about from the Pampanga River Basin. The south-east of the project area is not in this river basin.

Figure 13-36: Fish ponds in project area (only for Pampanga River Basin) (Images/maps: Google, TerraMetrics, 2014)



– Validation land use Appendix 19 This survey is held to create input for validation of the land use in the areas around Hagonoy and

Paombong. By means of 8 questions, farmers or those living close to the farms on certain specific locations

are asked about the land use and the (eventual) change over the years.

Questions:

1. What is produced on this land?

2. Has this situation always been like this?

3. When has the land use changed?

4. Who is the owner of the land?

5. Why has the land use changed?

6. Did you/the land owners ask permission for the land use change?

7. How did you/the farmers learn to deal with the new type of land use?

8. How do you see the future of the land use in this area?

Calumpit – Hagonoy Date: December 20, 2013

Interviewed by: Joris de Vos & Lorrie Mia San Pedro

Waypoint 601

1. In this area, there are mainly rice fields and some fish ponds.

2. There have been no significant changes in last 20 years in land use.

3. n/a

4. Some farmers are tenants, some harvest in their own land.

5. n/a

6. n/a

7. n/a

8. There is a possibility that there will be fish ponds here in the future, because there are a lot of

floods here.

Waypoint 602

1. There are only rice fields in this area.

2. There have been no significant changes in last 20 years in land use.

3. n/a

4. We are owners of the land.

5. n/a

6. n/a

7. n/a

8. In the future I expect lesser harvest because of the floods. I think we have to stop growing rice in

the future.

Waypoint 603

1. There are rice fields here, duck raising ponds and some small fish ponds.

2. Before there were pure rice fields, they could harvest three times per year before but now only

once a year.

3. The land use has changed 4 years ago, at that time three harvests per year were possible.


4. Most farmers here are tenants.

5. The land use changes because of floods and climate change. The small fish ponds were created

because we needed soil to put up a business along the road.

6. We had permission for the land use change.

7. The government organized a seminar for the farmers to teach them how to do something when

the water in the rice fields is still there after the rain or how to get additional income.

8. I think that this land will be mainly fish pond after 20 years. The elevation of the land is 1.5m below

sea level.

Waypoint 604

1. There are rice fields, fish ponds and vegetable fields.

2. Before, there were only pure rice fields here.

3. The land use took place more or less 15 years ago.

4. The owners of the land here harvest in their own land.

5. During high tide, sea water stays on the land. This is not good for the rice.

6. Yes, we did.

7. We came up with fish ponds because the rice fields harvest less now than before. We dig the land

to make a fish pond of it.

8. We think that this land will change, because before there were pure rice fields and now it is a

combination of rice fields and fish ponds. I think that the rice fields will disappear.

Waypoint 605

1. There are lots of fish ponds in this area.

2. Before there were no rice fields, just fish ponds.

3. n/a

4. Farmers here are tenants.

5. n/a

6. n/a

7. n/a

8. n/a

Waypoint 606

1. There are pure fish ponds here.

2. Before it was full of rice fields.

3. The land use change took place 13 years ago.

4. Former mayor Cruz owns a lot of fish ponds, we are tenant here.

5. The reason for the land use change is climate change: fresh water becomes salty.

6. n/a

7. There was a seminar about raising fishes in sea water.

8. In 20 years, the situation will be the same here: fishponds.

Waypoint 607

1. There are pure fish ponds, no more rice fields here.

2. Before, it was full of rice fields here.

3. 20 years ago was it changed.

4. There are tenants here.


5. The land use is changed because of salt in the water. Rice can’t grow anymore because of that.

6. The owner decides what to do in the land.

7. The farmers come up to do fish ponds because they learn from others that it can harvest more

than rice fields.

8. We don’t think that the agriculture will change here. The fish ponds will stay because of the salty

water.

Waypoint 608

1. Agriculture here is mainly fish ponds.

2. Before it was a combination of rice fields and fish ponds, but mostly rice fields.

3. This situation was 20-30 years ago.

4. We are the owner of the lands.

5. The land has changed because of flooding and because of the fact that houses are increasing here.

6. Yes.

7. People here come up in fish ponds because of their parents.

8. There is no chance that fish ponds turn back in rice field because of the floods every year.

Waypoint 609

1. There are just fish ponds here.

2. Before, the land here was used for rice fields.

3. We talk about 25 years ago when rice was planted here.

4. The owners of the land for fish ponds are the ones who manage it.

5. Because of the high tide, sea water enters the rice fields and it becomes fish pond. There could be

no irrigation. High tide lasts for one to two months.

6. No.

7. We copy the idea of raising fish in the ponds because we learn that it is easier to harvest than rice.

8. There is no chance to change the land use to go back to rice fields again.

Waypoint 610


2. Before, there was a lot of rice here.

3. This was 20-25 years ago.

4. n/a

5. It is because after the Mount Pinatubo eruption, ashes fall on the river and the river becomes

shallow. Fresh water does not enter here anymore. The river also becomes smaller because of the

increase of the houses.

6. The owner is the one who is responsible for the rice fields which become fish ponds.

7. n/a

8. There is no chance that the fields turn back in rice fields. Fish ponds will be here in 10-20 years

with higher harvests.

Waypoint 611


2. n/a

3. Since 1973 (since I have been here) is it fish pond.

4. n/a


5. Garbage is the cause that the river becomes shallow.

6. n/a

7. n/a

8. The status of agriculture here will not change in the next 10 or 20 years.

Waypoint 612


2. n/a


4. n/a

5. There have been no land use changes here.

6. n/a

7. n/a

8. I think there will be no change for the next 10 to 20 years, because we are close to the sea.

Calumpit – Paombong Date: December 20, 2013

Interviewed by: Frans Willem Hamer & Elmer Capiral Libiran

Waypoint 701

1. In this area, there is rice twice a year. On the other side of the road, there is vegetable.

2. This situation has been for ever since I know.

3. n/a

4. There are different land owners (1/2 ha)

5. n/a

6. n/a

7. n/a

8. Sometimes there are floods during extreme conditions. Sometimes we lose 30/40% of our harvest

due to that.

Waypoint 702

1. There is rice produced on this land. There are also some residences.

2. The residences are there since the canal moved away from the river.

3. n/a

4. n/a

5. n/a

6. n/a

7. n/a

8. There are no houses flooded since the dyke of 1970. Fields are flooding, there is no drainage

possible if there are heavy rains, because of the high level of the Angat. There is water of the Angat

canal in the irrigation canals.

Waypoint 703

1. Here, peanuts are grown one time per year, on 1,5 ha or one time rice in a year (this switched

every year). There are also vegetables grown here.

2. There is rice only once a year because there is no irrigation and there is no rice from December till

May due to salty water.


3. n/a

4. The owner of this land is the farmer.

5. There is only water for rice coming from rain. We stopped irrigation because of salt in 1991.

6. n/a

7. n/a

8. There are more floods, like this September, which is not normal for this region.

Waypoint 704

1. There is blue grass grown here for one year. For the rest other vegetables like eggplant, tomatoes.

2. Before, it was rice and sugar cane.

3. 5/6 years ago, the land use has changed.

4. We are owners of 4000 m3.

5. In May, June till November we can get water from the river, after that it is salty. The water comes

from a depth of 13 meters.

6. We did not ask permission for the land use change.

7. Friends and neighbours taught us here how to deal with the new land use.

8. This year, we lost a lot of vegetables. That’s why we are growing blue grass right now. This won’t

die due to flooding.

Waypoint 705

1. Now there are fishponds in this area. Harvests are large shrimps, milkfish and other fish twice a

year. There are also some vegetables. This is really the border of vegetables and fish ponds.

2. It was rice before, now the land is 0.5 meters deeper.

3. This situation was in the 1990s.

4. The farmers are the owners of the land.

5. The land use is changed due to the salt intrusion.

6. n/a

7. Farmers here learned from the agricultural office of the municipality. If the fish is 3 months old, we

harvest before the flood. The warnings come from TV.

8. n/a

Waypoint 706

1. On this farm, there are cocks for cock fighting right now.

2. Before, these fields were rice fields. The higher land is due to the soil coming out of the fish ponds.

The fish ponds around were rice fields before.

3. The fields changed a long time ago due to salty water.

4. n/a

5. There are check gates built here to make sure the salt water cannot go in. However, this is bad for

the flow in times of high discharges. Water cannot go out. There has not been any dredging for

more than 40/50 years. Now you can stand in the water here, earlier not.

6. Houses are built in the river here, no permission was asked for this.

7. n/a

8. n/a

Waypoint 707

1. The land here is used for fish farming: 1.6 ha. Milkfish, shrimp and lobster is grown here.


2. It has been rice before.

3. This was in the early ’90.

4. The owners of the fishponds are the owners of the land.

5. The land use is changed because of salt water. Our neighbours also changed in these times.

6. n/a

7. There was a guy who had a fish pond before it became salty here. It gave him a lot of profit so that

it the reason that we also changed to fish ponds.

8. If water muddy floods enter the fish ponds, the shrimps die. When the flooding comes, 100% dies.

Nets are around the fish ponds and we listen to warnings from the media. Putting nets takes 1 day

for 50 yards.

Waypoint 708

1. This is a rice field between many fish ponds.

2. n/a

3. n/a

4. n/a

5. n/a

6. n/a

7. n/a

8. n/a

Waypoint 709

1. There are fish ponds here.

2. Before it was rice. The whole area switched at the same time.

3. The conversion took place late 80s begin 90s.

4. Farmers are land owners, this farmer has 1.2 ha.

5. The change took place because of salt intrusion.

6. No permission needed for land use change.

7. Relatives and neighbours taught us how to deal with the new land use.

8. We expect more problems. In 2012/2013m there was 50/60 cm water in this place. Before there

were no problems. We use nets for protecting the fish.

Waypoint 710

1. There are fish ponds here: milk fish, tilopia, shrimp and big crabs are harvested.

2. Before, it was rice.

3. The land use change was 5 years ago. Other farms around changed 20 years ago.

4. n/a

5. Because of the salty water and high river discharges, the land was hard to cultivate.

6. n/a

7. For the switching, we go help from the government.

8. This year and last year, there was 20 cm of flooding. We protect the fish from swimming away by

big nets.

Waypoint 711

1. There are fishponds here. A farmer here has 3 ha. There is only milk fish.

2. Before, there was mangrove vinegar. They are still around however.


3. Fish ponds changed 30 years ago.

4. n/a

5. n/a

6. There is permission needed for the land use change.

7. They are trained by experience.

8. During flooding of 2011 and 2012, fish went out. We didn’t use nets because we were not

prepared like everyone. We used sandbags to protect the fish.

Malolos – Hagonoy Date: January 18, 2014

Interviewed by: Joris de Vos & Lorrie Mia San Pedro

Waypoint 344

1. In this area, there are fish ponds.

2. Before it was rice here.

3. Before the year 2000, there was grown rice here.

4. n/a

5. The reason for the land use change is the salt intrusion.

6. n/a

7. n/a

8. The people in this area think that the area could turn back in rice fields if there is not so much salt

water here during times of the year. At the moment this is not possible because of the many

floods.

Waypoint 345

1. There are fish ponds here: there are milk fish, tilapia, prawns and crabs.

2. Before it was rice here.

3. The land use has changed 35 years ago (around 1980).

4. The landowner is the Magsakay family.

5. The reason for the land use change is the salt intrusion.

6. n/a

7. n/a

8. The man here thinks that the rice cannot come back here anymore. The water from Manila Bay

doesn’t flow on its proper way. The area is full of structures now so the any way for the water is to

flow into their land.

Waypoint 346

1. There is no agriculture in this area: no rice paddies and also no fish ponds. Most of the people are

tricycle driver here. The land is mainly filled with houses.

2. Ever since the area here doesn’t have any rice fields or fish ponds.

3. n/a

4. n/a

5. n/a

6. n/a

7. n/a

8. n/a


Waypoint 347

1. There are fish ponds here. In the fish ponds, there is milk fish, tilapia, and prawns. There are also

some rice fields here.

2. There has been no land use change here before. The people who live here say that the floods

before (10 years ago) were very high, about 1.5 m above land level, but now there are no floods

any more.

3. n/a

4. n/a

5. n/a

6. n/a

7. n/a

8. n/a

Waypoint 348

1. There are fish ponds and rice fields here.

2. The situation was different. People could grow rice in places that are now fish pond.

3. The situation changed 10 years ago.

4. n/a

5. Because of the floods, there is no possibility to grow rice any more.

6. n/a

7. n/a

8. The land that was used for rice fields are now used for construction of buildings. So they cannot

turn back in rice fields any more. The fish ponds are now so salty that there is no possibility for the

rice to grow again they think.

Waypoint 349

1. There are only fish ponds in this area. In the fish ponds, there is milk fish, tilapia, mud fish and cat

fish.

2. Before it was all rice fields here.

3. The land use change was 8-10 years ago. The land use change was not gradually. Every fields was

changed in the same year.

4. n/a

5. The reason for the land use change is that the water levels in the land are too high for the rice to

grow and also the water is salty.

6.

7. n/a

8. The people here don’t think that the fish ponds can turn back in rice fields. The water gets saltier in

the years they expect.

Additional question: How much money does it cost to change a hectare of rice field into fish pond?

Answer: It costs about ₱30,000/100m2. This means that it costs ₱3,000,000/ha to change the land use.

Converted to Euros this is €48,902/ha.

Waypoint 350

1. There are fish ponds in this place.

2. n/a


3. n/a

4. n/a

5. n/a

6. n/a

7. n/a

8. n/a

Waypoint 351

1. There are rice fields and fish ponds here.

2. Before, most of the land was used for rice production.

3. Most of the land use change was 10-15 years ago.

4. n/a

5. The reason for the land use change the water that gets saltier.

6. n/a

7. n/a

8. People here think it is impossible to convert the fish ponds back to rice, because many former rice

paddies are quarried to become deeper to grow fish.

Waypoint 352

1. There are rice fields and fish ponds here.

2. Before, most of the land was used for rice production.

3. The land use change was more or less 10 years ago.

4. n/a

5. The reason for the land use change is the water that gets saltier, because the Pampanga delta gets

narrower.

6. n/a

7. n/a

8. The persons here think that the fish ponds cannot turn back in rice again because the land is dug to

become deeper to grow fish.



– Interview Mr. Angel Lontok Cruz Appendix 20

Part 1 - Date: December 11, 2013 - Interviewed by: Frans Willem Hamer & Joris de Vos

Can you tell something about yourself?

I have been a major for six year, and I found out that there is a lot to do in this world. My farm is an

example of how I created my love for the nature. I have chickens, rice and fish. I like it to use my products

from the farm in my restaurant. Before I have been a manager in this town and I lived in the Netherlands.

Further I am involved in the development of this community. How can I as manager, farmer, major

contribute to my community? Actually I am something like a social entrepreneur.

What are the most important problems in this area?

Water management is this most important problem here. I showed the director of the development bank

at my farm that there were mainly rice paddies. Now this is not the case anymore. This is a result of last

years, the river floods. 450 ha of the town is back to nature right now. Farmers have to deal with two

things, one: farmers cannot plant the rice because it’s too wet, and two: farmers don’t want to work

anymore, because every time you plant it’s a loss. This is coupled to the economic development of the

area.

Mr. Santos told us about the disaster risk and management team to look during floods what’s going to

happen on which scale. Did you bring something from the Netherlands? Or how did you do it?

It’s mainly a result of what happened here. I experienced many floods (4/5). As a major you are responsible

for the whole community and I wanted to protect this community. Because of our experience of floods, we

could make a plan about how we can better operate during the next calamity. This management team is

mainly set up because of our experience.

How was it before?

Before it was every man for himself. The government (provincial and municipal government), NGOs helped

us. Relief goods were shared, but no real emergency services were delivered.

We learned to deal with high threshold capacities in the Netherlands. Other capacities are coping capacity,

recovery capacity and adaptive capacity. How do you deal with these capacities?

We don’t know how to adapt our systems to increase the threshold capacity. The politics makes it difficult.

That’s what we are not strong about. However our population has a high coping capacity. Food supply is

well arranged. We have all the villages, and we split the town up in 5 sectors. In the north, we have the

most river floods. We know what should be the supply in emergency times for families here. We have

priority zones 1,2,3,4 and 5. We cannot bring all that food of course, however we know what we have to

buy and store for these people. Coping system is good. If people won’t go to strange and dangerous places

this is good. Recovery capacity should come from our people, but also from higher levels. Recovery of

bridges, roads and other infrastructure could not be our task, we simply can’t pay that. We can only

recover small projects like a fish paddy or so. Maybe our political system doesn’t allow to bring higher

threshold capacities to the area. We have elections every 3 years. This time span is simply too short to

implement important projects like increasing the threshold capacity of our system.

Who are involved in the politics here? Is it the top layer of the society?

This is an interesting question. The top layer here is not the highest educated layer. Many of our top

political persons don’t have the knowledge from an academic educations to broaden their knowledge.


Educational level is a problem here in politics. Our political persons mainly come up with populist solutions

for problems. Not science/knowledge based solutions.

The coping system during floods, is this the case for neighbouring municipalities too?

Yes, neighbouring municipalities also have implemented this coping system in the last years. There is a

disaster council for several political layers. Every municipality has their own coping plans because of their

own experiences. However, we implemented an alliance with our neighbouring municipalities in 2009.

There are all vulnerable for floods. The Dutch ambassador was present here as this implementation. The

majors were symbolic representatives. The main work is done by the municipal engineer or planner. How

can we develop plans to prevent floods and how can we fight water pollution. It is all related to water

management, but also related to disaster management.

Thinking about results from the alliance with the municipalities, is there already something developed?

No, I am the pusher of this alliance. The fact that you are here is a result of this alliance.

How is the building of houses arranged in this area, for example building in a river bank?

This is all arranged by the inhabitants itself.

How about land use? We walked on your terrain? The rights of the land: do people have their own piece of

land here?

Yes, they have their own piece of land and they can do with it what they want. There is a plan to monitor

the land, but this should be worked out better. The plan is more a wish. It is a development without a plan

right now. We think we can’t reach the optimum according to the plans. The land use is not optimal. For

example: someone could have salt water fish here and his neighbour is growing rice on his paddy. This was

the start of my initiative: I have to arrange something here! I thought it was reasonable to make land use

plans about agriculture and planning, but it really is a difficult thing. Collaboration between rice farmers

was there several years ago. However, since the transition from rice to fish took place, this collaboration is

gone. When I came back from Netherlands in 1996, we were growing rice. However, 6 years ago we

stopped with growing rice. The problem is the water level on the farms but also the saline groundwater.

How do you let water into your field and how does the water system in this area look like?

We do it via sluices and canals, but it also comes from the ground. The water in this area becomes much

more saline. Because of deepening and straightening of specified canals, the salt water comes in much

faster than earlier.

How did the shift from rice to fish take place? What are the signs for these shifts.

The shift from rice to fish is gone gradually. I experienced in 1996 that fish farmers had rice growing tools

on their lot. You can clearly see on some lots that rice agriculture took place. Rice tools are a clear mark.

It’s clear to see that rice agriculture took place. Also the names of the towns tell something about the

history. A certain name could mean something related to rice field while fishponds are there instead of

rice. This is also an indication. The transition from rice to fish does not go gradually. Rice only has shallow

water levels, while fish ponds demand bigger depths. Other indications for changes to fish ponds is that

you see more people on the street. People lose their jobs because fish ponds don’t need much labor

instead of rice.


Go people to school here to determine their own future or are they encouraged to do the same work as their

parents?

The educational system right now is that people with money go to college. However, for the big mass there

are not many professions to be taught. 8 out of 10 student finish lower school. 4 of 8 go further to high

school and finish it. 1 out of 10 initial students finishes college. These people are business man, engineers,

etcetera. Many people try to find work abroad because they can earn more money there. Many families (1

out of 8) have a family member working abroad. More or less 4000 people here in Hagonoy are employed

abroad. Foreign companies come to The Philippines to recruit people to work abroad. Most of the people

working abroad have a basic education. For example a young farmer here drives tricycle here or work in

the construction industries.

Do investors buy large areas of land here?

There are some large fish pond owners. These people have for example 500 ha fish ponds. You don’t want

to know what they pay their workers. I think this amount is below 200 PHP.

Part 2 - Date: December 13, 2013 - Interviewed by: Frans Willem Hamer & Joris de Vos

How is the political system arranged here?

It is a too simple organized system. There is a village council with a head, after that the municipality with a

major, the province with the governor and council and the region which is not chosen. For the regional

level, a lot of bureaucracy is involved. There is a lot of bureaucracy involved if decisions have to be

implemented: decisions, policy etcetera. That is difficult here. In The Philippines, there are not political

parties. It’s more that people come together to form a group before the elections start. It’s pure to be

chosen. There are no political programs or principles. On national level, there are two parties: the first

party is the ruling party, the other one is the opposition. During elections, the mission of the parties is to

get chosen, not to show their views. Popular people are brought together to get the votes.

Is there are tasks structure in the governmental system?

For infrastructure, there are national roads and other infrastructure. My experience: the municipality has

experiences with infrastructure, but if the government has other priorities, the project of the municipality

is not implemented. Between the different governmental layers, there is no discussion. The little discussion

which is there, is not about water but mainly about roads and other infrastructure.

Is there during a water engineering issue like the building of the dikes along the Pampanga discussion with

the municipalities or is it more a top down process?

It’s a top down discussion. Municipal planners or engineers should be more involved in these kind of

projects.

Is there regulation in the municipality here?

Yes there is a municipal officer. For example: I came back in 1996 and I wanted to know more about rice. I

talked about it under a mango tree with a neighbor farmer. I wondered where to get advice. He said that I

should go to the municipality. The advisers there said: you have to plant 1 ha instead of only 0.5. So I

thought it was easy to grow rice initially. There is not much information more to get. So I went to the

province and an institute called: The Philippine Rice Institute to learn more about rice. I went to seed

producers and other co operations afterwards. Also seminars are there now to learn more about rice.

About the change to fish ponds in this area, we get no help. All the farmers who changed from rice paddies

to fish ponds have thought about it by themselves. There is no official system regarding this.


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