rapid hazard and risk assessment post-flood return analysis

RAPID HAZARD AND RISK ASSESSMENT

POST-FLOOD RETURN ANALYSIS

UNESCO on behalf of OCHA and UNCT, NEPAL Funded by UNDP

Supported by ICON/ADAPT Nepal

TABLE OF CONTENT

TABLE OF CONTENT....................................................................................................... II

LIST OF TABLES..............................................................................................................IV

LIST OF FIGURES.............................................................................................................V

1 INTRODUCTION .................................................................................................. 1

1.1 BACKGROUND .......................................................................................................... 1 1.2 OBJECTIVES/SCOPE OF THE STUDY................................................................................ 2 1.3 METHODOLOGY AND ORGANIZATION OF THE REPORT ..................................................... 3 1.4 LIMITATION.............................................................................................................. 6 1.5 ASSESSMENT TEAM.................................................................................................... 6

2 RIVER KOSHI AND THE BREACH ....................................................................... 8

2.1 INTRODUCTION ......................................................................................................... 8 2.2 RIVER SYSTEM........................................................................................................... 9

2.2.1 Sunkoshi Basin..................................................................................................... 10 2.2.2 Arun River Basin.................................................................................................. 11 2.2.3 Tamur River Basin................................................................................................ 12

2.3 KOSHI AREA TOPOGRAPHY....................................................................................... 12 2.4 THE KOSHI PROJECT ................................................................................................ 14 2.5 CHARACTERISTICS OF THE RIVER KOSHI CHANNELS WITH RESPECT TO GEOMORPHIC

CONTEXT GENERAL ......................................................................................................... 18 2.6 RIVER CHANNEL CHARACTERISTICS........................................................................... 19

2.6.1 River Channel Geometry and Processes..................................................................... 20 2.6.2 Response of Koshi River in Altered Conditions ........................................................... 23 2.6.3 Historical Records................................................................................................. 26 2.6.4 Sediment Load...................................................................................................... 26 2.6.5 Bed and Flood Profile Slopes.................................................................................... 27

2.7 SPUR FAILURE ......................................................................................................... 30 2.8 HYDROLOGICAL ASPECTS.......................................................................................... 36 2.9 ASSESSMENT OF THE EVENT OF THE EMBANKMENT BREACH FLOOD ON 18TH AUGUST 2008. 40

3 OBSERVATIONS FROM THE FIELD VISIT......................................................... 44

3.1 AREA AND PEOPLE AFFECTED .................................................................................... 44 3.2 PROPERTIES LOST ..................................................................................................... 45 3.3 BREACH REPAIR...................................................................................................... 52 3.4 CONDITIONS OF THE SPURS AND MAINTENANCE.......................................................... 52 3.5 REHABILITATION WORKS IN PROGRESS ....................................................................... 54 3.6 ASSESSMENT OF BREACH FLOOD RISK......................................................................... 54 3.7 EXPOSURES TO POTENTIAL RISK................................................................................. 57 3.8 LOCAL CAPACITY TO COPE WITH FLOOD RISK ............................................................... 63 3.9 FLOOD RISK MANAGEMENT...................................................................................... 65

3.9.1 The August 2008 breach flood ................................................................................. 65 3.10 PREPAREDNESS ....................................................................................................... 74 3.11 FLOOD FIGHTING AND PREPAREDNESS ( FF&P)............................................................ 75

4 CONCLUSIONS AND KEY ISSUES..................................................................... 77

4.1 INTRODUCTION ....................................................................................................... 77 4.2 TECHNICAL ISSUES:.................................................................................................. 77

Rapid Hazard and Risk Assessment Final Report: 20 March 2009 Koshi River Embankment Breach

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4.3 INSTITUTIONAL ISSUES:............................................................................................. 79 4.4 SOCIAL ISSUES ......................................................................................................... 79 4.5 PREPAREDNESS ISSUES: ............................................................................................. 80

5 RECOMMENDATION FOR RISK REDUCTION.................................................. 82

5.1 IMPROVING PREPAREDNESS ....................................................................................... 82 5.2 PREPARATION OF FLOOD STANDING ORDER ................................................................ 83

5.2.1 Nepal-India History of Flood Forecasting Cooperation ................................................. 84 5.2.2 Review of the existing hydrological and meteorological network ..................................... 88 5.2.3 Strategy to prepare a Flood Standing Order............................................................... 90

5.3 ASSESSMENT OF EARLY WARNING SYSTEM (EWS) AND STRATEGY FOR CREATING EWS ..... 91 5.4 MAINTENANCE OF SPURS.......................................................................................... 95 5.5 COMPREHENSIVE STUDY TO REDESIGN THE SPURS ......................................................... 96 5.6 DAM BREAK ANALYSIS.............................................................................................. 97 5.7 GENERATING ‘WHAT-IF SCENARIOS’ ........................................................................... 98 5.8 MONITORING MECHANISM........................................................................................ 98 5.9 MANPOWER TRAINING:............................................................................................ 99 5.10 CONSTRUCTION OF RETIRED EMBANKMENT................................................................. 99 5.11 LONG TERM ISSUES – CLIMATE CHANGE......................................................................100 5.12 RECOMMENDED ACTIVITIES AND RESPONSIBILITIES ......................................................101 5.13 MEDIUM TERM PLAN ..............................................................................................102

6 REFERENCES......................................................................................................103


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LIST OF TABLES

Table 2.1: Aggradation/Degradation of the River Koshi (GFCC & CBIP, 1986)..........26

Table 2.2: Hydraulic Parameters of the Koshi River (GFCC & CBIP, 1986).................29 Table 2.3: Flood frequency analysis at Chatara ............................................................38

Table 3.1: Number of households and population figures for the affected VDCs.......44

Table 3.2: Number of deaths and injuries .....................................................................45 Table 3.3: Loss of /damage to private properties.........................................................46

Table 3.4: Extent of damage to cultivated land............................................................46

Table 3.5: Number of livestock lost...............................................................................47 Table 3.6: Loss of crops in quintal.................................................................................48

Table 3.7: Loss of fruits in quintal.................................................................................48

Table 3.8: Losses of vegetables in quintal.....................................................................49 Table 3.9: Loss of household goods in number.............................................................50

Table 3.10: Estimated monetary loss...............................................................................50

Table 3.11: Loss/damage of roads and trails..................................................................51 Table 3.12: Damage toinfrastructure..............................................................................51

Table 3.13: Number of days when the flow of goods and services were closed ............52

Table 3.14: Elements exposed to the potential risk of breach flood in Koshi.................59 Table 3.15: Area under different levels of risk and population......................................60

Table 3.16: Area under different levels of risk by land types.........................................61

Table 3.17: Number and percentage of houses located with different levels of flood risk.................................................................................................................61

Table 3.18: No. and percentage of livestock owned by households with different

levels of flood risk.........................................................................................62 Table 3.19: Major crops with level of risk.......................................................................62

Table 3.20: Number and percentage of public buildings, industries and structures

by the level of flood risk ..............................................................................63 Table 3.21: Number and percentage of items of infrastructure by level of flood risk....63

Table 3.22: Number of households by major occupation...............................................64

Table 3.23: Number of households by size of landholding............................................64 Table 3.24: Number of households by annual income category.....................................65

Table 3.25: Number of households by level of food sufficiency from own

production.....................................................................................................65 Table 3.26: Number of households and population in vacated camps located on the

western bank of Koshi River. ........................................................................67

Table 3.27: Number of camps by size of population ......................................................68 Table 3.28: Number of people by sex and other status...................................................68

Table 3.29: Number of families by ownership of land ...................................................69

Table 3.30: Number of household and population living in the camps by the place of origin.........................................................................................................69

Table 3.31: Number of camps with/without service facilities .......................................70

Table 3.32: One month’s expenditure on different items in the camps..........................70 Table 3.33: Number of camps reporting sufficiency in the distribution of goods and

services ..........................................................................................................71

Table 3.34: International/National Agencies Involved in Relief by Sector....................72 Table 3.35: Number of people willing/not willing to return home ...............................73


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LIST OF FIGURES

Figure 1-1: Assessment Framework............................................................................4

Figure 1-2: Framework for Analysis ...........................................................................5 Figure 2-1: Koshi River Basin......................................................................................9

Figure 2-2: Koshi Topography..................................................................................14

Figure 2-3: Major River Control Structure................................................................17 Figure 2-4: Historical Shifting of Koshi River...........................................................21

Figure 2-5: Satellite Picture of the lateral shifting and Alluvial fan of river Koshi .22

Figure 2-6: Channel Characteristics ..........................................................................24 Figure 2-7 Relationship between river discharge and sediment load at Koshi

Barrage at Hanuman Nagar (Garde et al., 1990) ....................................28

Figure 2-8: Schematic representation of the breach location with respect to the spurs at chainage 12.1 kmand 12.9km (Not to scale).............................33

Figure 2-9: Google Image 2004 showing concentration of flow. ..............................34

Figure 2-10: Google Image Showing Breach exactly on the concentrated flow.........35 Figure 2-11: Mean daily gauge height at Chatara from 12, Aug to 25 Aug, 2008 ......37

Figure 2-12: Average monthly discharge at Chatara..................................................37

Figure 2-13: Maximum instantaneous flood discharge in Koshi at Chatara..............39 Figure 2-14: Mean daily discharge at Chatara and mean daily rainfall for 12 Aug to

18 Aug, 2008............................................................................................39

Figure 3-1: Potential Breach Points and Flow Paths.................................................55 Figure 3-2: Google Earth Image showing concentration of flow upstream of the

breach (1=Current Breach, 2= Prakashpur, 3= Rajabas and

4=Pulthegaunda).....................................................................................56 Figure 3-3: Area under risk and major ethnic groups ..............................................58

Figure 3-4: Risk classification of the Koshi Basin below Chatra until the Barrage...60

Figure 3-5: Shelter Camps in the Area......................................................................67 Figure 3-6: Area Covered by Sand and Water..........................................................73

Figure 5-1: Conceptual Approach to Koshi Flood Preparedness .............................83

Figure 5-2: Line Diagram of Hydrometric Station on Koshi and its Tributeries in India ........................................................................................................86

Figure 5-3: Hydrometric and Precipitation Station in Koshi Basin..........................87


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1 INTRODUCTION

1.1 Background

1. Flooding is a common phenomenon in the Himalayan Rivers. Every year

floods affect thousands of people in the Himalayan region. Every year the

monsoon floods of immense magnitude from the Himalayan Rivers cause

huge loss in terms of damage and disruption to economic livelihoods,

businesses, infrastructure, services and public health. Long term data on

natural disasters suggests that floods are by far the most common cause

of natural disasters in this region. This has both an immediate effect such

as loss of life by drowning as well as a long term effect such as the spread

of disease. Fifty five percent of all people whose lives have been affected

by natural disasters are the victims of flooding. Between 1980 and 2008,

every year an average of 10 million people suffered flood damage, a

statistic which makes floods the most devastating of all natural disasters.

2. Flooding is already one of the most widespread of hydrometeorological

hazards, and international panels such as IPCC and ISDR have predicted

that it is very likely that flood hazard will continue to increase in many

areas of the world, including the Himalayan region, (McCarthy et al.,

2001). Both the number and magnitude of flood risks are increasing. This

increase is partly due to an uncertainty in the way that natural

phenomena are understood and interpreted, and partly due to the

increasing vulnerability of people living in the flood plain or in an area

with high exposure to a flood event.

3. The Koshi flood that occurred on the 18th of August had a devastating

impact. The disaster occurred due to the breach of eastern embankment

of the Koshi barrage at Kushaha of Sunsari district. The flood entered into

the settlements damaging national highways, power transmission lines,

communication cables, schools, health posts, village roads and private

and public buildings. After the initial rescue and relocation works

carried out by the administration, security forces and NGOs, the


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immediate remedial measures for flood control are being carried out to

restore the pre-flood situation in the affected district. The objective of

ongoing repair and construction works is not only to repair and retrofit

the damage caused, but also to create a situation such that it is safe for the

internally displaced people (IDP) to return to their homes and farms.

1.2 Objectives/scope of the study

4. Although the Koshi River is now flowing back within the guided

embankment, there are several activities that need to be undertaken to

ensure that such disasters do not happen again. There was an immediate

need to undertake a risk and vulnerability assessment to ascertain :

a. Risk for and vulnerability of the IDPs in returning back to their

place of origin vis-à-vis the quality and pace of repair and

construction work along the embankment, especially the breach

area;

b. Adequacy of flood preparedness and early warning;

c. Likelihood of return of the flood in the area.

5. The broader objective of this assignment was to carry out a rapid

assessment of the ongoing remedial measures undertaken for the Koshi

Floods in terms of hydraulic and structural effectiveness. More

specifically, the objectives of the assignment were::

a. To make a qualitative and quantitative assessment of the

immediate vulnerability of the flood affected people of Koshi,

especially a risk and vulnerability analysis of the quality and pace

of ongoing repair works vis-à-vis the flood displaced community

in a participatory manner;

b. To assess the adequacy of flood preparation and the early warning

mechanism in the flood prone region;


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c. To assess the likelihood of the scenario of the return of floods of

similar magnitude and the potential for disaster.

d. To develop a risk management plan to deal with possible flooding

that will facilitate coordination between agencies, including the

UN system agencies

e. To prepare a medium term action plan and an implementation

plan.

1.3 Methodology and Organization of the report

6. This report was prepared on the basis of a rapid assessment of the

disaster stricken area. The team, comprised of senior government officials

from Nepal, consultants from both India and Nepal and led by a UN

official, visited the breach site and undertook a detailed investigation on

the cause of the breach and analyzed the existence of pre-breach hazard

and vulnerability in the area. The work was undertaken at the request of

UNCT, Nepal.

7. This report is an outcome of 8 days (4 -11 Feb 2009) of extensive fieldwork

by experts, 30 days of hydrological data collection and assessment both in

Kathmandu and in the field (21 January – 18 February, 2009) and 30 days

( 30 January – 1 March, 2009) of socioeconomic data collection. While the

fieldwork of the experts mainly involved high-level interactions and

measurements, the latter two involved all three methods of data

collection – review of literature, survey at Village Development

Committee (VDC) level and observation. Published and unpublished

documents, information sheets and maps from relevant institutions were

collected and reviewed. All the affected VDCs and those located along the

Koshi river bank and its adjoining areas and all the shelter camps and

institutions located in local areas were surveyed with the help of

structured check lists. The current situation of the river channel

morphology, spurs and embankment were observed.


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8. For vulnerability assessment, a total of 17 VDCs were surveyed. Among

them 12 VDCs1 were affected by the flood and the remaining 5 VDCs are

adjoining VDCs. Information at VDC level was generated through group

discussion. Social mapping was another important aspect in the collection

of field information. The group was requested to identify different levels

of flood hazard-prone areas within their VDCs, based on their

experience/perception and to delineate such areas in the toposheet on the

scale of 1:25000. The participants in the group discussion included VDC

secretary, ex-chairman, ex-ward chairman, leaders of different political

parties, social workers, businessmen etc. The size of the group in most

cases ranged from 10-12.

9. Similarly a total of 26 shelter camps were surveyed. Group discussion

was organized in each camp. The participants in the group discussion

included members of the shelter camp management main and sub-

committees, the camp supervisor, the health worker and internally

displaced people living in the respective camps.

10. Both the relevant spatial and attribute data so far collected from the field

has been integrated with the help of GIS tool (Arcview) for the

assessment of damages and potential risk in the future.

Figure 1-1: Assessment Framework

1 Only 4 VDCs have been frequently reported as breach flood affected area. Many VDCs in the south east of Sunsari district were also affected by the flood water. However, the loss in those VDCs was negligible.

Social

Causes

Technical

Causes

Institutional

Causes

Breach


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11. The report has analyzed the probability of hazards and the existing

vulnerabilities along three critical areas which, based on the initial

deliberation, the team has identified as the key reason for the breach. The

primary causes for breach, broadly grouped as technical, social and

institutional complexities, or interplay there of, have been highlighted in

the succeeding chapters.

12. The report is written by taking into consideration the Hyugo framework

for action.

Figure 1-2: Framework for Analysis


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1.4 Limitation

13. This is a preliminary assessment at the pre-feasibility level. This is limited

only to Nepal and only for the eastern bank of the Koshi River, although a

cursory visit and observation was also made of the Western

Embankment. The level of field information generated for this study is at

VDC level, through group discussion. Likewise, the identification of the

potential breaching site was done based on the discussion with the key

informants and visual observation without making detailed investigation

of the properties of the materials used and the sheer strength of the

construction.

14. It must be noted that this report has been prepared to facilitate

humanitarian assistance and is not an attempt to question any bilateral

understanding which exists between India and Nepal. The content of this

report is not the view of UN agencies, but solely that of those who were

involved in the rapid assessment and how have they interpreted the

situation on the ground. Therefore the content of this report should in

no way be used as a bilateral negotiation tool.

1.5 Assessment Team

15. The Assessment Team involved senior government officials from Nepal,

Experts from Both India and Nepal.

a. Dr. L.P. Devkota, Hon. Member NPC

b. Mr. M. Dangol, Joint Secretary, MOWR

c. Mr. M. Gurung, DG, DWIDP

d. Mr. Adarsha Pokhrel, Former DG, DHM

e. Mr. R. Khadka, Regional Director, DWIDP

f. Prof. Prakash Adhikari, Department of Geology, TU

g. Prof. P.P. Mujumdar, Indian Institute of Science, Bangalore,

India

h. Prof. U.C. Kothyari, IIT, Roorkee, India


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i. Mr. D.B.Yadav, Officer In-charge Regional office of DHM, Dharan

j. Prof. Narendra Khanal, Department of Geography, TU.

k. Dr. Sanjeev Shah, Structural Engineer, ICON

l. Mr. Srijan Aryal, Hydrologist, ICON

m. Dr. K.N.Dulal, Hydrologist, Nepal

n. Dr. B.R. Neupane, UNESCO


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2 RIVER KOSHI AND THE BREACH

2.1 Introduction

16. The event proved beyond the reasonable doubt that the burden of loss, of

course, is greatest in poor communities, where previous studies have

shown that thirteen times more people die from flood events compared to

their rich counterparts. Economic losses also tend to be larger as a

proportion of the total economy of poorer communities tends to be

uninsured. The current flood has also proved that a natural disaster

knows no boundaries, economic background or ethnicity and is unbiased

in its assault. Koshi disaster impacted on two countries, affected millions

and perhaps pushed back the pace of development in the impacted area

by several decades, by hitting hard on local economies, health, quality of

life, education, politics and perhaps stability of the area.

17. This corroborates the common wisdom on flood management that there

is a dire need to share information on existing flood preparedness and

adopt practices that are best for the area. Enhanced preparedness is

obviously better than cure after the flood has impacted on the area.

Understanding the fact that floods can still return, there is a need to

undertake unilaterally, bilaterally or multilaterally the design and

establishment of an integrated system of flood management and

forecasting.

18. Complacency on the part of the authorities regarding existing strategies

and actions on monitoring, opted modalities for repair and maintenance,

confidence over the existing system of mutual cooperation, reliance on

available facilities for flood fighting and lack of emergency preparedness

all have played a distinct role in the breach that caused massive damage

and destruction and led to about 55 deaths thus far. Having said this, one

of the biggest contributors to the disaster is the very limited knowledge of

the Koshi River itself, which remains one of the least understood and

least studied rivers in Nepal. The information available about this river is


9

insufficient in terms of what is normally required to better understand a

river.

2.2 River System

Figure 2-1: Koshi River Basin

19. The Koshi River basin is the largest river basin in Nepal (Fig 2.1). It

comprises of about 61, 000 sq.km. Out of a total catchment area of 27, 816

sq. km. (45.6%) lies in Nepal and the remaining 33,1845 sq.km. lies in


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Tibet. In addition to the Koshi River basin, the other two major basins are

in Nepal namely; the Karnali and Gandaki River basins.

20. The River Koshi also commonly known as Sapta Koshi comprises of

seven rivers namely (From west to east); Indrawati, Sunkoshi, Tama

Koshi, Likhu, Dudh Koshi, Arun and Tamor. Out of these three major

rivers or tributaries originate in Tibet; namely; the Sun Koshi, Tama

Koshi and Arun. Broadly, the basin of Koshi can be divided into three

major river sub-basins; the Sunkoshi, Arun and Tamor. The Sunkoshi

River comprises of the Indarwati, Sunkhoshi, Tama Koshi, Likhu and

Dudh Koshi rivers.

2.2.1 Sunkoshi Basin

21. The catchment area of the Sunkoshi basin is about 19,000 Km2. The

Sunkoshi River originates in the mountain range east of Barhabise called

Kalinchowk, and flows in a westerly direction with steep river gradients

of 1:10 to meet the Bhotekoshi at Barhabise. The Bhotekoshi, originates

from a glacier on the south slope of Mt. Xixabangma Feng, in the

southern part of the Himalayan range in the Tibetan plateau. The

catchment area at the confluence point is about 2,375 km2 of which about

2000 km2 lies in Tibet. The average gradient in the upper reach is 1:8,

while in the lower reach it is about 1:31.

22. The Sunkoshi flows in a south-east direction up to Dolalghat, the

confluence point of the Sunkoshi with the Indrawati River, with an

average gradient of 1:130. The Indrawati River, one of the main

tributaries of the Sunkoshi River, originates in the Himalayan range and

flows in a south, south-east direction to meet with the River Sunkoshi at

Dolalghat. The average gradient of this river is about 1:34 in the upper

reach and 1:194 in the lower reach. The total catchment area of the

Indrawati at the confluence with the Sunkoshi River is about 1,175 km2.

The Sunkoshi River, after the confluence with Indrawati River, flows in a

south-east direction up to Tribeni with an average gradient of 1:450.


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23. The Tamakoshi River, which originates in the southern part of the Tibetan

Plateau of China, flows in a southerly direction through the Rolwalin

Himalayan range and enters Nepal. Within Nepal, the river flows in a

southern direction through the mountainous and hilly areas with an

average gradient of 1:20 in the upper reach and 1:110 in the lower reach to

meet with Sunkoshi River at Khurkot. The Tamakoshi River has total

drainage area of 4,190 km2 at Khurkot. About 40 km downstream of

Khurkot, the Sunkoshi River joins with the Likhu Khola.

24. The Likhu Khola originates in the mountain areas and flows towards the

south to meet the Sunkoshi River. The average gradient of Likhu Khola is

about 1:54. Its drainage area at the confluence point with the Sunkoshi is

1,070 Km2. The Sunkoshi River after the confluence with Likhu Khola,

meets with the Dudhkoshi about 25 km downstream.

25. The Dudhkoshi originates in the Khumbu and Nojumpa Glaciers located

on the southern slopes of the Mahalangur Himalaya range and flows

directly from north to south resulting in a rapid river gradient. The

average gradient is about 1:30 in the upper reach and 1:250 in the lower

reach. The total drainage area of the river (at the confluence with the

Sunkoshi River) is about 4,140 km2.

26. The Sunkoshi River flows in a south-eastern direction to meet the Arun

and Tamur Rivers to form the Saptakoshi at Tribeni. The total length of

the river is 330 km. The gradient of the Sunkoshi River is approximately

1:210 through out the entire length of its course in Nepal.

2.2.2 Arun River Basin

27. The Arun River originates from a glacier on the northern slope of Mt.

Xixabangma Feng (El.8012m), part of the Himalyan range in the southern

part of the Tibetan highland. The river is called Pengqu within Tibet. It

flows eastward almost parallel to the Himalyan range in upper reaches

for a distance of about 280 km and then makes a sharp turn to the

southwest at the junction with its tributary, the Yenuzangbu River (in


12

Tibet), forming a big bend. The Arun then flows southward crossing the

Himalyan range into Nepal. It continues to flow south and joins the

Saptakoshi (Koshi) River at Tribeni. The total length of the river is about

510 km and the total drainage area is about 36,000 km2, out of which

25,310 km2 lies in Tibet. In Tibet it has a gradient of 1:130 and 1:630 in

upper and lower reach, respectively. When it enters in Nepal it has a

steep slope in the range of 1:30 to 1:50 in upper reach. In the middle reach

of Nepal it has a slope of 1: 96 and in lower reaches it has a slope of 1:300

to 1: 400.

2.2.3 Tamur River Basin

28. The river has its source in the High Himalayas. Near its source the

Tamur is called Medalung Khola. Before becoming the Tamur River it is

joined by a large khola called Yangma Khola. The north boundary of the

Tamur catchment lies in high Himalayas and delineates the border

between Nepal and Tibet. Similarly the eastern boundary lies in the High

Himalayas and delineates the border between Nepal and India.

Kanchanjanga (at an elevation of 8586m) the world’s third highest peak

lies in this basin. In addition, there are 13 other major peaks in the basin,

ranging from 5938 m (Ganbul on northern border of Nepal with Tibet) to

7902 m (Kambachen inside Nepal).

2.3 Koshi Area Topography

29. The altitude of the basin ranges from only 65 m near the Nepal-India

border in the south to 8848 m in the north within a short distance of

about 150 km. The channel gradient in the north is high, as a result the

tributaries are powerful in terms of erosion and transportation. When the

river debouches from the mountain areas near Chatra its gradient is

decreased and the channel pattern becomes braided. In the south near the

border and the barrage area, the relief of the channel bed is only 0.5 - 0.6


13

m/km. There are marked differences in the discharge between winter

and summer. The minimum recorded discharge is 280m3/s whereas the

average flood discharge during the monsoon period is about 11400 m3/s.

The long term average discharge in August is 4729 m3/s. The recorded

peak discharge was 25878 m3/s in 1968 (Dixit, 2009). Six events of

extraordinary flood in the Koshi River have been reported by local

people. These were in 1954, 1962, 1969, 1979, 1988 and 1996. One

extraordinary flood event usually occurs every 7-10 years. The river is

heavily loaded with sediments. It brings about 120 million cubic meters of

sediment every year of which about 90% is transported during monsoon

period. The major sources of sediment in the mountain areas are

landslide, debris flow, rockfall, avalanche, glacial lake outburst, active

down cutting of the river bed and bank erosion etc.. Due to such a high

sediment load, the river channel in the Terai, south from Chatra, is very

dynamic. This river has shifted about 115 km from the east to the west in

the last 220 years (Gole and Chitale, 1996 cited in Dixit, 2009). This

shifting of the Koshi River in the west is in the reverse topographic

gradient associated with the shifting of channel bars, due to excessive

sediment concentration in the river. The topography of the Piedmont

area has been tilted from north-west to south-east as shown by the

contours (Figure 2). There is therefore the possibility of the river

shifting eastwards by avulsion, a fact which was realized long ago

(Chorely, 1984).


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Figure 2-2: Koshi Topography

2.4 The Koshi Project

30. The Koshi Project was framed with the purpose of flood control,

irrigation, generation of hydropower and prevention of erosion. An

agreement incorporating all the terms and conditions was signed on the

25th April, 1954 by the government of Nepal and India. The project

components consisted of the construction of a barrage, afflux and flood

banks, canals and protective works (Figure 3). A barrage was constructed

in Nepal about 15 km upstream from the international boundary between

Nepal and India. The construction of the Barrage was completed in 1964.

Similarly, embankments and spurs were constructed on both the banks in

order to control the flow and floods. A 32 km long embankment and


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spurs on the west bank and a 29 km long embankment with 46 spurs

were constructed by the project. The major work for the construction of

embankment and spurs was completed in 1959 some years ago when the

construction of the barrage was completed. A railway line was

constructed along the embankment between the barrage and

Chatra/Ghopa for the purpose of transporting construction materials

such as stone. After the completion of the construction work of the major

structures its operation was stopped and almost all the materials used in

the construction of railway line have been stolen.

31. The original agreement of 1954 between Nepal and India was

amended in 1966 (GoN, 1975). Some of the provisions of the amended

agreement of 1966 are as follows.

a. Any construction work for the project within Nepal is carried out

in consultation with the Government of Nepal.

b. Investigations and surveys for the general maintenance and

operation of the project are carried out by the Union

(Government of India) after due intimation to the Government

of Nepal.

c. All the data, specimens, reports and other results of surveys and

investigations carried out by the Union are made available to the

Government of Nepal freely and without delay. Similarly,

relevant data, maps, specimens, reports and other results and

surveys and investigations carried out by the Government of

Nepal are made available to the Union.

d. The Government of Nepal permits necessary access for the

execution of construction works including occupation of necessary

land.

e. No customs duty or duty of any kind, during construction and

subsequent maintenance, on any article and materials required


16

for the purpose and project and work connected therewith, are

not to be charged for by the government of Nepal.

f. Compensation for lands required for the execution of various

works, submerged lands, houses and other immovable

property and loss of land revenue is paid by the Union.

Compensation, in every case is tendered by the Union through

the Government of Nepal to the owners of the land for all

accidents that may have occurred .

g. Assessment of the compensation and the manner of payment is

determined jointly by mutual agreement.

h. Preference is given to Nepali labor, personnel and contractors for

the construction work where available. .

i. The establishment of a joint Indo-Nepal Koshi Project

Commission for the discussion of problems of common interest in

connection with the project and for purposes of co-ordination and

co-operation between the two governments. Until the joint

commission is formed, provision is also made for a temporary

coordination committee for the Koshi Project, in order to solve

the problems associated with land acquisition, the rehabilitation of

displaced people and maintenance of law and order.

j. As per the agreement, the Government of Nepal has established

Liaison and Land Acquisition Offices in Biratnagar with 25 staff.

These salaries of these staff are paid by the Koshi project. The

Liaison Office facilitates the import of construction materials

whereas the Land Acquisition Office keeps land records for

compensation.

32. The Koshi Project agreement between Nepal and India indicates that

the role of the Government of Nepal is limited to facilitation of the

project with very limited role in major decision making processes for

investigation of the embankment and river control structures and their


17

proper maintenance work. Similarly, the involvement of local people and

institutions that are likely to be affected by the failure of the flood control

structure in carrying out monitoring, maintenance and repair, is rather

poor. The perceived ownership by the local people of the protection of the

river control structure is very critical. . During the field work it was

observed that there was no gabion wire at the surface of almost all the

spurs constructed by the project, between 13-29 km lengths of the

embankment. However, the spurs constructed by the Sunsari-Morang

Irrigation Project during 1978-79 a few kilometers upstream were found

with the gabion wire intact.

Figure 2-3: Major River Control Structure


18

33. Another major project in the Piedmont area is the Sunsari-Morang

Irrigation Project. It was originally implemented as a Chatra Canal Project

under grant aid from the Government of India in 1964. The main canal

has a length of 53 km with a net total command area of 73,000 hectares

(Figure 2.3). The intake site is located near Chatra. During 1978-86, the

Koshi river control works were carried out and the embankment and

spurs were constructed.

34. The Koshi Tappu Wildlife Reserve between 6-25 km upstream from

the Barrage with an area of 175 sq. km, was established in 1976. It

was also recognized as Ramsar site in 1987.

2.5 Characteristics of the River Koshi Channels with respect to Geomorphic Context General

35. In general terms, the drainage basin of the Koshi River can be divided

into three main zones: an upper erosional zone of sediment production, a

middle zone of sediment transport with simultaneous erosion and

deposition, and a lower zone of sediment deposition. Flooding is more

common in the lower zones where the river overflows frequently onto

adjacent agricultural and other areas on both banks.

36. In the case of the Koshi River, the longitudinal profile of the stream

system tends to flatten through time by degradation in the upper reaches

and aggradation in the lower reaches. As in most of the natural river

systems this process is also slow enough to be of little engineering

concern; but in the case of the Koshi River the process is remarkable. It

has been observed that after the intervention on the Koshi River during

1950, profile flattening has been proceeding at very noticeable rates. The

flattening of the longitudinal profile was found to proceed rather

dramatically, especially in the lower zones after the construction of an

afflux bund for the Koshi Barrage and an embankment for flood

protection.


19

37. After assessments of the basin and channel system geomorphology

including historical maps, aerial photographs, satellite images,

hydrological records, geological and soils reports, ground reconnaissance,

and consultation with local residents and specialists, it was observed that

during the design and implementation of the Koshi Project during the

1950’s, more attention had been given to hydraulic design studies

whereas insufficient attention had been given to stability and

sedimentation aspects. In other words, stability was addressed to a great

extent but insufficient attention was given to long-term effects and

responses within and beyond the project area.

2.6 River Channel Characteristics

38. The lower zone of the Koshi River (from the foot hills of Nepal to the

downstream section ) comprises of an alluvial fans channel where the

river emerges from a mountain valley onto relatively flat land. In this

zone, the depositional tendency of the river channel is found to be

prominent. Depositional features are usually characterized by quantities

of coarse to fine alluvial materials. Similarly, unstable multiple channels

subject to frequent shifts or “avulsions” is a common phenomenon in the

lower zone of the river. It was also observed that the main channel is

often “perched” on the highest ground a number of times. It was

observed with the help of historical aerial photographs and through

interaction with senior local people, that deposition of sediment is highly

noticeable during the historical flood events in the alluvial fan and the

stream is eroding into earlier deposits dramatically. In general, the main

features of the river in the area of concern are (i.e. lower zone) the

formation of multiple channels and coarse deposits which are dynamic in

nature. The results of this phenomenon further deteriorate the stability

problems of the channel by sudden shifts in channel direction, erratic

deposition and degradation in the channel.


20

39. Embankments and other structure stability problems on this type of

alluvial fan include avulsion of the river at a point upstream of the

barrage structure or along river training works, thereby bypassing the

structures and infilling of the designed conveyance channel with coarse

to fine sediment deposits. Although, it was observed that flood control

works have been provided sufficiently far upstream of the barrage and

afflux bond stretches, however consideration for trapping or removal of

the sediment upstream of the flood control zone has been found lacking.

2.6.1 River Channel Geometry and Processes

40. In general, channel geometry has four main components: planform, cross

section, slope (gradient), and bed topography. The term “channel

processes” generally refers to natural changes in planform, cross-sectional

boundaries, longitudinal profiles, and bed topography.


21

Figure 2-4: Historical Shifting of Koshi River


22

Figure 2-5: Satellite Picture of the lateral shifting and Alluvial fan of river Koshi

41. The planform has been discussed in river channel characteristics. It was

also mentioned in several references to the shifting nature of the Koshi

River before construction of the guide bunds during the 1950’s. Therefore,

before the implementation of a guide bund on both sides of the river

planform of the Koshi River changed frequently due to its shifting nature

(Fig 2.4). A satellite picture of the lateral shifting of the river Koshi and its

alluvial fan is presented in Fig 2.5. However, now the shifting of the river


23

has been restricted within the bund. Relationships between planform and

other aspects of geometry and processes of Koshi River are difficult to

systematize. In order to establish some relationship of planform and other

aspects of geometry and processes, the river has to be vigorously

monitored and assessed on a regular basis for the long term.

42. In general the cross section of a natural channel depends on basin runoff,

sediment input, and boundary soils and vegetation. Although under

natural conditions the average cross section usually does not change

much over a period of years, in the case of the Koshi River it was

observed that cross sections on the lower zone have been altering

frequently and temporarily during medium to severe floods.

43. Further, in the Koshi River channel the process of cross-section

enlargement by erosion is prominent on one bank and has been observed

by most people. This is mainly because the loss of banks and adjacent

properties are much more of a social issue than the shrinkage on the

opposite bank. Shrinkage of the cross section varies considerably. The

phenomenon of shrinkage of the cross section in the Koshi River is

mainly due to significant differences in the rate of deposition and the rate

of sedimentation during medium to severe floods.

2.6.2 Response of Koshi River in Altered Conditions

44. Instability and sedimentation have two aspects with respect to

construction of the barrage and afflux bund in the Koshi River: the impact

of existing processes on the project, and the impact of project changes on

the stream system both within and beyond the project length. In the case

of the Koshi River, it has been observed that the first aspect has been

taken greater care of than the second aspect. It should be noted that, the

flooding of adjacent banks and the breaching of the embankment of the

Koshi River were due to non-consideration of second aspect. The figure

below illustrates concepts for long term formation and the response of the

Koshi River. It is clearly illustrated that with the alterations in the


24

controlling variables (boundary conditions) of the river, the river will

respond by altering the cross section, slope and planform.

Figure 2-6: Channel Characteristics

45. Following are some expected changes in channel characteristics with

changes in driving variables or boundary conditions.

a. With an increase in river discharges, the channel width and depth

increases, resulting in slope reduction and increased bank erosion.

Generally widths vary more or less as the square root of

discharge, other things being constant. Widening in response to

increased flood discharges can generally be expected. In the case

of reduced discharges, ultimate narrowing can be expected if the

channel carries enough sediment to deposit on the banks or on

side bars.

b. Depths increase with the increase of discharges, but not as much

as compared to width. Depths will generally decrease with an

increase in bed material inflow, as slopes increase.


25

c. Similarly if bed-sediment load increases, the depth is reduced

with a remarkable increase in the bed slope, resulting changes in

planform, especially by increasing bars and channel splitting. This

may increase channel erosion.

46. The most widely known geomorphic relationship embodying slope and

the equilibrium concept is known as Lane’s (1955) Principle and can be

expressed in the form:

QS ~ QS D50

where

Q = discharge, ft3/sec

S = slope, ft/ft

Qs = bed material discharge, tons/day

D50 = median sediment size, ft

47. The periodic devastating floods on the Koshi River can be attributed to

the raising of the bed of its embanked channel by sediment brought down

from upper catchment, followed by the raising of the banks, whereby the

river is forced to flow above the level of the plains. When the river was

first embanked during the 1950’s, a considerable space was left between

the embankments and its banks on each side, so that sufficient space has

been provided to allow deviations in the channel and in consideration of

two main aspects; that a large area would be available for the depositing

of sediment and that a good width of channel would be available for

flood discharge. However it has been observed that the channel keeps on

shifting to the either side of the riparian land left within the

embankments and exposed to every flood. The boundary of the inner

embankments were formed close to the river, thereby greatly confining

the flood-waters, and consequently raising the flood-level and the river-

bed and therefore exposing these embankments to undermining by

merely a moderate change in position of the river channel.


26

2.6.3 Historical Records

48. Most of the left bank tributaries of the River Ganga originate in the

Himalayas and carry an enormous amount of silt. The problem of bank

erosion in these rivers is very common. The Koshi Rver shifted east-

wards over a distance of 112 kms in a period of about 225 years. In 1963,

the Koshi Project was constructed with a barrage at Hanuman Nagar and

with embankments along both the river banks. Earlier a disastrous breach

of the eastern embankment had occurred in 1984. An excessive silt load

and the consequent aggradation of the river bed are believed to be the

main cause of the braiding plan form of river and also that of the shifting

tendency of its numerous channels.

49. Detailed studies on the aggradation problem of the Koshi River were

carried out earlier (Garde et al., 1990) at IIT Roorkee (formerly the

University of Roorkee). The river bed levels were observed to mostly

aggrade in different reaches post the construction period of Koshi Project

in 1963 as per the table below.

Table 2.1: Aggradation/Degradation of the River Koshi (GFCC & CBIP, 1986)

River reach Bed variation during 1963-

74 (Post-barrage) in mm/yr

From To

Length of the reach (in

km)

Bed level variations

during 1955-62 (pre-barrage) in mm/yr

(-)Scouring; (+) Silting

1 2 3 4 5

Chatra Jalpapur 27 (-) 17.6 (+) 123.4

Jalpapur Bhimnagar 15 (-) 165.6 (+) 107.0

Bhimnagar Dagmara 26 (-) 35.6 (-) 08.3

Dagmara Supaul 34 (-) 03.8 (+) 18.6

Supaul Mahesi 40 (+) 95.6 (+) 63.5

Mahesi Koparia 25 - (+) 120.3

2.6.4 Sediment Load

50. The recorded peak flood discharge of the River Koshi is 25,800 m3/s. The

minimum discharge of the river is about 280 m3/s and its annual average

run off is 5.8 m ha.m. The sediment concentration at the point of debouch


27

from the gorge is about 0.2 percent by volume. The river carries little

coarse sediment; about 0.02 percent of the total load. The percentage of

fine silt in sediment concentration is more than 50%. The average

sediment load per 100 km2 is estimated as about 19 Ha.m. The variation

of suspended sediment with river discharge is depicted in the Fig. 3

where d represents the average size of the bed sediment.

2.6.5 Bed and Flood Profile Slopes

51. The recorded (past) values of highest flood levels (HFL), the slope of the

HFL and the bed slope of the River Koshi in the different reaches are

given in the table below. The distance between the Chatra Gorge to the

outfall of the Koshi on the Ganga near Kurushela is about 161 m and the

total fall in bed level is about 79.25 m. The slope of the head reach is

about 0.95 m per km but it flattens to 0.03 per km in the tail reach.


28

Figure 2-7 Relationship between river discharge and sediment load at Koshi

Barrage at Hanuman Nagar (Garde et al., 1990)

52. The drastic reduction in bed slope results in the marked reduction of

sediment transporting capacity and hence causes significant aggradation.

However the observed sediment concentration of the Koshi increases in

the head reach up to Hanuman Nagar (Table-2.2). This increase is

primarily due to an increase in fine fraction which finds its way into the

river due to erosion of the Belka hill face on the head reaches. Beyond

Hanuman Nagar, the sediment concentration however progressively

reduces and in the final reach of the river, coarse and medium fractions

are very small compared to the fine fraction.

CUSECS


29

Table 2.2: Hydraulic Parameters of the Koshi River (GFCC & CBIP, 1986)

Sr. No.

Station (starting upstream)

Distance (in km)

Suspended sediment load

in terms and percent of corresponding

values at Barakshetra

HFL (in m)

HFL slope (in

m per km)

Bed level (in m)

Bed

slopes (in m per km)

1. Chatra 0 109 110.18 - 102.16 -

2. Galpharia 17.71 111 - 0.95 - 0.89

3. Raniganj 41.86 - 70.74 - 65.08 -

4. Hanuman Nagar

51.52 141.5 - 0.50 - 0.42

5. Bhaptiahi 74.06 - 56.98 0.21 51.79 0.19

6. Saupaul 114.31 - 48.38 - 44.27 -

7. Karahara 123.97 96.5 - 0.12 - 0.23

8. Dhamra Ghat

210.91 - 36.25 - 19.58 -

9. Basua 238.28 27.5 - 0.32 - 0.023

10. Nagchia 296.24 - 33.35 0.074 17.19 0.057

11. Kursela 318.78 24 31.70 - 11.12 -

53. Because of a typical river morphology and huge sediment deposition, the

Koshi is characterized by a large number of small, local islands due to

braiding. This causes the flow to be constricted in narrow channels with

increased velocities. Further, the braids themselves change in shape, size

and location depending on the flow and sediment characteristics which

therefore adds complexity to flood protection measures for the river

system.

54. With these complexities there has to be a paradigm shift in management

of the Koshi River floods from ‘river control’ to ‘river management’

which emphasizes an integrated approach and addresses the cause rather

than the effect (Brierley and Fryirs, 2005). The river management strategy

must include modern approaches such as satellite-based monitoring and

system dynamic approaches integrated into user-friendly decision

support systems.


30

2.7 Spur Failure

55. The Koshi River is one of the typical Himalayan rivers possessing some of

its own specific evolutionary history besides the common characteristics

that it shares with the others. Generally, a combination of embankments

with spurs is provided in flood protection measures. Spurs at regular

intervals are provided to protect flood embankments. Spurs generally

minimize scouring on the embankment by moving the scour-causing

turbulence away from the embankment. Therefore, spurs are necessary to

protect the bank and the embankment from which they are projected and

deflect the current away from the bank.

56. In general, there are three reasons for embankment breach:

a. Overtopping-high flood, silt deposition

b. Piping- seepage and leakage due to rat holes, inappropriate

material and insufficient compaction

c. Scouring-flow concentration, high flood

57. To tame the Koshi River, different river training works have been

followed. The most commonly used structures to protect the bank erosion

and flood controls in the Koshi River are the construction of marginal

embankments and spurs. There are numerous spurs regularly arranged

from Chatra to the Koshi Barrage on the eastern (and western) side of the

Koshi River. Marginal embankments are constructed parallel to the bank

line, which shed regular spurs transversely into the river. The marginal

embankments near the Koshi Barrage acts as guided banks as well. The

spurs constructed more than 40 years ago are still functioning. The older

spurs are constructed ofearthen material; while the recently built spurs in

the upper reaches of the fan are of masonry bounded by woven wire nets.

Most of the spurs are at right angles to the riverbanks, but a few become

oblique due to the later action of river.

58. The marginal embankment along the eastern side of the Koshi River from

the Koshi Barrage to Chatra was focused on for the present study. The


31

embankment has a dual purpose , one for protecting the eastern area

from flooding and the other is serving as an embankment service/village

road. The embankment was constructed about 50 years ago, while the

embankment around west of Prakashpur and the Chakraghatti area are

newer. The older one was constructed using earthen material and the

latter was constructed using stone masonry with soil covering. The

embankment is about 2 to 3 m in height from the general surface i.e. the

bottom of the embankment, (which was more than 5 m above the water

surface of the river during the field inspection), and 5 m in width at the

top and 7 to 8 m at the bottom. The action of the embankment upstream

of the Koshi Barrage becomes evident by noting the elevation difference

of the ground on the riverside and the outer side of the embankments.

The elevation in some areas reaches up to 2 m or more. The elevation

differences become more just downstream of the spurs radiating into the

riverward side from embankment.

59. The spurs along the banks of the Koshi River are built to obtain certain

objectives, such as:

a. To train the river along the desired courses by attracting, or deflecting the flow in the desired direction.

b. To reduce the concentration of flow at a particular point of attack.

c. To create the slack zone for silting up the area.

d. To protect the bank by keeping the flow away from it.

60. In general, the spurs on the eastern bank of the Koshi River worked

satisfactorily to protect the area until the event of 18th August 2008.

61. The spur has two types of sedimentary processes, erosional and

depositional processes on either side, i.e., upstream and downstream

sides. The upstream side of the spur represents the site of erosion, and the

downstream side is the site of siltation, i.e., site of deposition. By

maintaining the good spacing between spurs, the worst effects of erosion

on the upstream side can be mitigated. The consequence of improper

spacing of the spurs has occurred at some locations. An example of one of


32

the worst cases of this occurred near the Salbandi village, Sunsari

district..

62. The breaching of the embankment on August 18 2008 took place due to

the failure of the upstream and the down stream spurs at the breach

point. The successive failure of a downstream spur (12.1 km from the

Barrage) and then an upstream spur (12.9 Km) allowed the stream

channel to shift from its previous location to the adjacent embankment.

The failure was due to the effect of scouring rather than to the magnitude

of the flood. The magnitude of the flood on that particular day had been

assessed with the help of gauging data at Chatra, which concluded that

the flood level was even less than 5 year return period flood in Koshi

River.

63. Figure 2.8 below shows a schematic of the breach portion with respect to

the spurs at chainage 12.1 km and 12.9 km. The spur at chainage 12.1 km,

which had eroded considerably over the last few years and was not

restored to its original length, was hit first. The nose portion of the spur –

which is the most critical structural part of a spur – failed because of the

high velocity of flow. Once the nose portion was eroded, the spur did not

have the structural strength and protection to resist further damage and a

rapid failure of the spur ensued.


33

Figure 2-8: Schematic representation of the breach location with respect to the spurs at chainage 12.1 km and 12.9km (Not to scale)

64. After a significant length (about 60%) of the spur at 12.1 km was eroded,

the impact was transferred to the spur at 12.9 km and, also being in

structurally bad shape already, the spur started giving way. As the two

protections gave way, the brunt was borne by the embankment and the

breach occurred, as the embankment was structurally not capable of

taking the entire impact.

65. The hydraulic/technical reasons for the breach are twofold : (a) The flow

has been concentrated near the east bank for several years now, and the

formation of local islands due to large amounts of silt deposition has

canalized the flow in a narrow funnel leading to increased velocities

locally. The Google imageries below show the concentration of the flow

in a narrow space around the spurs at 12.1 km and 12.9 kms, for about the

last four years and (b) the two spurs were in structurally bad shape,

having been insufficiently-maintained over the years, and therefore,

although the flood discharge was not very high, the spurs failed.

Flow direction

Spur at 12.1 KM

Spur at 12.9 KM

Breach location

Local island created by silt

deposition

Embankment


34

Figure 2-9: Google Image 2004 showing concentration of flow.


35

Figure 2-10: Google Image Showing Breach exactly on the concentrated flow

66. Therefore, after the collapse of the spurs at 12.1 km and 12.9 km, scour

causing turbulence hit the toe and sides of embankment between the

stretch (12.1 to 12.9 km) causing embankment failures of even during one

of the lowest flood levels in Koshi.

67. Spurs are built either perpendicular to the bank or embankment or at an

angle inclined slightly upstream for flood protection. The falling of trees

on the river between two constructed spurs generally falls in the

downstream direction . The falling of a large number of trees in this

fashion, together with grass and other debris, acts as natural spurs

causing the scour hole to form closer to the bank and tends to maintain

the river current close to the bank, as attracting spurs. Therefore trees

falling between the constructed spurs during flood always enhance the

chances of attracting the river channel more towards the embankment

sides.


36

68. Most flood protection and river engineering projects in the Indian

subcontinent are based on Lacey’s Theory. According to Lacey’s Theory,

scour depth is a function of discharge and silt factor. Generally, in order

to determine the level of scour, the river discharge and silt factor have

been taken for micro levels (overall flood discharge over full width of

river). However, in the case of a river with a splitting tendency, into a

number of channels, the scour level of channels adjacent to the bank can

be more critical than the overall river scenario during flood. This may be

one of the reasons for failure of the spurs.

69. The breach of the spur at 12.1 km occurred over a period of more than 24

hours, and if an early warning system was in place, there was adequate

time to issue warnings on the possible breach of the embankment.

2.8 Hydrological aspects

70. The mean flood discharge during August 2008 which contributed to the

breach of the embankments was 5120 m3/sec and occurred on 16 August

2008 (Fig 2.11). On 19th August this discharge was exceeded and rose to

5190 m3/sec. Similarly, the area had not experienced any significant

rainfall that would have caused this. The breach, however, had already

occurred on 18th August and hence the higher discharge (of 5190 m3/sec)

did not directly contribute to causing the breach.


37

Figure 2-11: Mean daily gauge height at Chatra from 12, Aug to 25 Aug, 2008

71. The analysis of the observed flow record at the Chatra gauging station in

the Koshi basin shows that the average annual flow is about 1600 m3/s

and the peak flood has generally occurred in June to July where the

monsoon rain dominates the river flow regime. About 80% of the total

annual rainfall occurs during the monsoon season.

Figure 2-12: Average monthly discharge at Chatra


38

72. The extreme flow in the Koshi River at Chatra station was 25879m3/s in

1968 followed by 24241 m3/s in 1954 and then about 24000 m3/s in 1980.

The flood flow on 18 August 2008 at Chatra was only about 4250 m3/s

when the flood disaster in the Koshi River was initiated while the mean

precipitation was about 2.4mm. The discharges shown in Table XX for the

period 12th August 2008 to 25th August 2008 are all not significantly high

in comparison with the critical flood discharges in the Koshi river. Based

on a flood frequency analysis, the discharge of the flood with a five year

return period at Chatra is 11578 m3/sec (with log Pearson III

distribution). The design discharge of the Koshi Barrage (located

downstream of the breach site) is about 27,000 m3/sec. The maximum

instantaneous flood discharges in previous years have varied from 5630

m3/sec to 24000 m3/sec. (Figure 2.13)

Table 2.3: Flood frequency analysis at Chatra

Flood (m3/s) Return period

Gumbel (Extreme value I) Log-Pearson type III

5 13703 11578

10 17021 14862

20 20202 18739

30 21835 21336

40 23081 23346

50 24328 25009

60 25051 26438

70 25774 27699

80 26391 28832

90 26903 29864

100 27415 30813

73. Flood frequency analysis at Chatra (Table 2.3) shows that the flood flow

on 18 Aug, 2008 is less than the magnitude of the five year return period

flood. The return period of flooding in 1980, which was 24000m3/s, is

between 40 to 50 years.


39

Figure 2-13: Maximum instantaneous flood discharge in Koshi at Chatra

Figure 2-14: Mean daily discharge at Chatra and mean daily rainfall for 12 Aug to

18 Aug, 2008

74. The breach, therefore, did not occur because of a high flood discharge,

but rather because of the concentration of flow in a narrow channel and

because of vulnerability due to badly maintained spurs. Discharge at

Chatra was 4250 m3/s (149940 cfs) and at the Barrage 4800 m3/s (169344

cfs), which is much lower than the flood in 1980 and the design discharge


40

of the Barrage, whereas the average daily rainfall on 18 August was 2.4

mm only. The 10 year return period flood is 12,831 m3/s. From these

facts, it can be concluded that the breach was not due to hydrological and

meteorological extremes. The embankment was breached due to

scouring. The reasons for scouring may be the following:

a. Concentration of flow towards left bank at the breached site for

the last few years.

b. Rise in river bed level due to sediment deposition.

c. Drainage congestion due to opening of only 34 gates out of 56

gates on August 18, that contributed to the scouring of spurs.

d. Lack of proper inspection, observations and regular maintenance

of the spur and a prompt engineering response recognizing the

criticality of the problem.

2.9 Assessment of the Event of the Embankment Breach Flood on 18th August 2008

75. As noted the Koshi River cut two spurs and an embankment in the east

and consequently its flow diverted to further south east on 18th August

2008, when the discharge was far below the long term average high

flow. Complete breaching of the embankment occurred at 12:55 PM.

Since, the danger of breaching was realized since the early morning and

local people were informed about the potentially dangerous areas, they

had decided to evacuate before the breach. The speed of the breach was

not so high at the beginning. It took about one and half hours for the

flood to reach the highway.

76. The breaching of the embankment was neither due to the overtopping of

water over the embankment nor was it due to a seepage of water. It was

due to the change in the flow direction to the embankment on the one

hand and the weak shearing properties within the embankment on the

other. It was also partly due to slackness in regular monitoring,

maintenance and repair of the spurs and embankment.


41

77. The need for the maintenance and repair of the spurs and embankment

was realized one month back before the breaching occurred. The office of

the Koshi Tappu Wildlife Reserve was requested for permission to clear

trees and bushes along the embankment and to permit entry of

construction materials without any obstruction through the office of the

Chief District Officer. However no permission was granted until the day

of the breaching.

78. There was also a one week bandh (strike) called by Terai Madhes

Loktantrik Party between 12-16 August. It was reported that the

continuous cutting back of the spur-12.10 by the river was noticed on 15th

August but the flood fighting work was hindered due to the

combination of different events - evacuation of the area by the army

for gun firing on the same day, bargaining for wages by the local

laborers, the theft of gabion wire from the project site, attempts to set fire

to the Koshi Project officials’ vehicles, delays from the customs office in

granting permission for the import of construction materials and

desertion of Koshi Project staff from the potential breach site for security

reasons at midnight on the 17th of August. They returned to the breach

site only on the 22 August, i.e., four days after the breach when security

was ensured for their return.

79. In many places, the spur length has been reduced by 20-80 m due to

cutting by the river. However, no attempt has been made to bring them to

their original design length. After this flood disaster, the project has

considered repairing many spurs but it has only considered extending it

by 10 m.

80. Reportedly, a test model is being conducted at the Pune Research Lab and

the results of the test will be used as a basis to redesign the spurs and

their lengths. It will be a very welcome move to reduce underlying risk

on the area.

81. Before 1988 when an earthquake of 6.6 on the Richter scale occurred, with

its epicenter in the Udaypur district, the larger portion of water flowing


42

was on the western side of the embankment. After this event the flow had

diverted to the eastern part, damaging most of the spurs along the eastern

embankment.

82. As per the agreement and general practices of the project, the inspection

is carried out during the lean season of the river. Reportedly, the

maintenance and repair works take place during the lean season,

however, the focus is also kept on flood fighting (normally between 15th

June and 15th October). During this period, most of the spurs and the

embankment are covered with bushes and shrubs. As a result access to

the spur, embankment and reaches of the river becomes poor. It also

hampers the identification of potentially hazardous sites where breaching

could occur and in the carrying out of maintenance and repair works.

83. As discussed earlier, shifting of the river channel and diversion of flow by

avulsion are common geo-hydrological processes even in a natural

braided channel in the Terai. For example, the Sundari – one of the

tributaries of Koshi completely changed its channel and flow direction

during and after the floods of 1973 (Khanal, 1993). Seven events of flood

disaster due to breaching of the embankment have been reported from

Bihar and Nepal between 1963 and 1991. Among them, two events – one

in 1963 at Dalwa and another in 1991 in Joginiya on the west bank, a few

km downstream from the Koshi Barrage have been reported (Mishra,

2006 cited in Dixit, 2009). Flood disasters due to breaching of the

embankments have also been reported from other areas of Nepal. Many

people were swept away and a huge amount of property was damaged

due to the embankment breach flood in the Tinau River near Butwal in

1981 and the Rapti River in the Makawanpur and Chitwan districts in

1993 (Khanal, 1996).

84. The threat of breaching of the embankment after cutting of the spur toe

was noticed 17 km from Prakashpur in 1993. However, the breach and

the subsequent disaster were averted through active flood-fighting with

the active participation of the local people. It is very difficult to say if the


43

breach of 2008 could have been averted if similar measures had been

taken. However an attitude of complacency about flood recurrence is

quite noticeable.


44

3 OBSERVATIONS FROM THE FIELD VISIT

3.1 Area and people affected

85. A total of 12 VDCs were affected by the flood of August 2008 (Table 3.1).

And within this total of 6183 households about 40% of the households in

these VDCs were affected by this flood. The number of households

affected differs with the sources of information. One estimate shows a

total number of 7306 only in the VDCs of Shreepur, Haripur and Paschim

Kusaha. Another source shows a total of 7584 displaced families (CDO

Office, Sunsary). Almost all the households in Haripur and Shreepur

Jabadi were affected. The percentage of affected households decreases

with the increase in the distance from the breach site.

Table 3.1: Number of households and population figures for the affected VDCs

SN Name of the VDCs

Total number of

households

Total number of population

Number of household affected

% of affected household

1 Haripur 1580 9006 1580 100.0 2 Shreepur Jabadi 2250 13500 2250 100.0 3 Paschim Kusaha 2000 11800 1000 50.0 4 Ghuski 1682 10365 300 17.8 5 Basantapur 668 3941 350 52.4 6 Laukahi 909 4920 68 7.5 7 Narsimha 2835 17689 110 3.9 8 Ramgunj Sinuwari 1639 9991 105 6.4 9 Devangunnj 1650 10725 104 6.3

10 Sahevgunj 705 3873 109 15.5 11 Madyaharsahi 910 5364 55 6.0 12 Kaptangunj 1410 8643 152 10.8 Total 18238 109817 6183 33.9

Source: Field Survey, February, 2009

86. There was only one reported fatality from the flooding. However, the

number of deaths reached 55, mostly in the shelter camps (ref: CDO

Office, Sunsari). Table 3.2 shows the number of dead and injured people

as reported during the discussions in the surveyed VDCs. The number of

deaths ranged from 2 in Ghuski VDC to 3 in Paschim Kusaha, 16 in

Shreepur Jabadi and 19 in Haripur. Among the reported total of 40


45

deaths, 18 were female and 6 were children. Many of them had died due

to diarrhea. The total number of injured people were 2350, of whom 898

were female and 816 were children. The number of injured women and

children is relatively high.

Table 3.2: Number of deaths and injuries

Death Injury

SN

Name of the

VDCs Male Female Children Total Male Female Children Total

1 Haripur 7 8 4 19 120 150 200 470

2 Shreepur Jabadi 8 6 2 16 500 700 600 1800

3 Paschim Kusaha 0 3 0 3 12 35 6 53

4 Ghuski 1 1 0 2 1 1 0 2

5 Basantapur 0 0 0 0 3 12 10 25

6 Laukahi 0 0 0 0 0 0 0 0

7 Narsimha 0 0 0 0 0 0 0 0

8 Ramgunj Sinuwari 0 0 0 0 0 0 0 0

9 Devangunnj 0 0 0 0 0 0 0 0

10 Sahevgunj 0 0 0 0 0 0 0 0

11 Madyaharsahi 0 0 0 0 0 0 0 0

12 Kaptangunj 0 0 0 0 0 0 0 0

Total 16 18 6 40 636 898 816 2350


3.2 Properties lost

87. Table 3.3 shows the losses of and damage to property from the flooding.

A total of 5985 Bighas of cultivated land, 230 pakki houses and 3167

kachchi houses, 323 ordinary sheds and 89 ponds were destroyed by the

flood. Almost all the cultivated land in the three VDCs namely Haripur,

Shrepur Japadi and Paschim Kusaha was damaged by the flood. Large

parts of cultivated land were covered by a thick layer of sand and gravel.


46

Table 3.3: Loss of /damage to private properties

House (no)

SN

Name of the VDCs

Land

(Bigha) Pakki Kachchi

Sheds

(no)

Pond (no)

1 Haripur 2200 30 400 0 14

2 Shreepur Jabadi 1500 150 1700 0 35

3 Paschim Kusaha 1300 50 880 300 20

4 Ghuski 200 0 54 0 7

5 Basantapur 50 0 25 0 3

6 Laukahi 120 0 0 0 1

7 Narsimha 150 0 0 23 0

8 Ramgunj Sinuwari 75 0 16 0 0

9 Devangunnj 85 0 55 0 2

10 Sahevgunj 130 0 9 0 4

11 Madyaharsahi 65 0 11 0 0

12 Kaptangunj 110 0 17 0 3

Total 5985 230 3167 323 89


88. Another estimate of damage to land shows a much higher area of nearly

8200 Bighas damaged by the flood, in only four VDCs. by only. Nearly

46% of the area was totally damaged and the remaining 54% was partially

damaged.

Table 3.4: Extent of damage to cultivated land

Name of VDC

Total land area in Bigha

Totally damaged land area in

Bigha

Partially damaged land area in Bigha

Paschim

Kusaha 2473 477 1996

Laukahi 584 0 584

Haripur 2087 624 1463

Shreepur 3063 2663 400

TOTALS 8207 3764 4443

89. Table 3.5 shows the number of livestock lost due to the flood. The number

of deaths of cows, buffalos and goats were 1000, 1180, and 7306,

respectively. These were mainly confined to the three VDCs namely;

Haripur, Shreepur Jabadi and Paschim Kusaha. Another major loss was


47

fish. The loss of fish was considerable even in the downstream areas such

as Kaptangunj and Sahebgunj.

Table 3.5: Number of livestock lost

SN Name of the

VDCs Cow Buffalo Goat Chicken Duck Pig Fish

1 Haripur 150 100 500 5000 1000 0 5000

2 Shreepur Jabadi 250 280 5000 12000 0 0 200000

3 Paschim Kusaha 600 800 1800 4000 1000 300 15000

4 Ghuski 0 0 0 300 0 0 30000

5 Basantapur 0 0 6 200 0 0 30000

6 Laukahi 0 0 0 0 0 0 10000

7 Narsimha 0 0 0 150 0 0 0

8 Ramgunj

Sinuwari 0 0 0 112 0 0 0

9 Devangunnj 0 0 0 55 0 0 0

10 Sahevgunj 0 0 0 65 0 0 3500

11 Madyaharsahi 0 0 0 50 0 0 0

12 Kaptangunj 0 0 0 115 0 0 10000

Total 1000 1180 7306 22047 2000 300 303500


90. Table 3.6 shows the quantity of standing crops damaged and loss of grain

stored in the house because of the floods. The standing crops were paddy,

sugarcane and jute. The quantity lost ranged from 39800 quintal of

sugarcane to 79214 quintal of rice and 2170 quintal of jute. Similarly, the

loss of stored grains ranged from 4940 quintal of wheat to 5427 quintal of

maize and 635 quintal of potato.


48

Table 3.6: Loss of crops in quintal

SN Name of the VDCs Paddy Wheat Maize Potato Sugarcane Jute

1 Haripur 3744 1085 240 100 25000 1000

2 Shreepur Jabadi 35437 1500 1000 500 350000 200

3 Paschim Kusaha 27850 300 200 0 0 100

4 Ghuski 1020 20 10 6 100 60

5 Basantapur 1200 1000 500 0 3000 200

6 Laukahi 2040 0 0 0 20000 500

7 Narsimha 1845 50 30 0 0 0

8 Ramgunj Sinuwari 1095 32 29 0 0 58

9 Devangunnj 1127 568 3100 0 0 37

10 Sahevgunj 1729 225 213 23 0 0

11 Madyaharsahi 438 45 15 6 0 0

12 Kaptangunj 1689 115 90 0 0 15

Total 79214 4940 5427 635 398100 2170


91. Table 3.7 shows the loss of fruits from the flood. The estimated loss of

mangoes, jack fruit, bananas, guavas and litchis is 4620, 2370, 300, 100 and

500 quintal respectively. The loss of fruits is confined to three VDCs,

namely Haripur, Shreepur Jabadi and Paschim Kusaha.

Table 3.7: Loss of fruits in quintal

Name of the VDCs Mango Jack

fruit Banana Guava Litchi

Haripur 200 70 0 0 0

Shreepur Jabadi 3000 1500 0 0 500

Paschim Kusaha 1200 800 300 100 0

Ghuski 70 0 0 0 0

Basantapur 50 0 0 0 0

Laukahi 35 0 0 0 0

Narsimha 3 0 0 0 0

Ramgunj Sinuwari 3 0 0 0 0

Devangunnj 12 0 0 0 0

Sahevgunj 25 0 0 0 0

Madyaharsahi 12 0 0 0 0

Kaptangunj 10 0 0 0 0

Total 4620 2370 300 100 500


49

92. Table 3.8 shows the estimates of vegetables damaged by the flood. The

estimated loss of pumpkin, bottle gourd, cucumber, pointed gourd, chili,

aborigine, okra and arum was 1062, 40219, 102, 31015, 10000, 1200, 10 and

30 quintals. Again, Haripur, Shreepur Jabadi, Paschim Kusaha and

Ghuski were affected most.

Table 3.8: Losses of vegetables in quintal

Name of the VDCs Pumpkin Bottle gourd Cucumber

Pointed gourd Chili Aborigine Okra Arum

Haripur 200 150 80 0 0 0 0 0 Shreepur Jabadi 0 40000 0 30000 10000 0 0 0 Paschim Kusaha 0 0 0 15 0 0 10 30

Ghuski 1400 0 0 1000 0 1200 0 0 Basantapur 0 0 0 0 0 0 0 0 Laukahi 0 0 0 0 0 0 0 0 Narsimha 0.5 0.5 0.5 0 0 0 0 0

Ramgunj Sinuwari 0 0 7 0 0 0 0 0 Devangunnj 0 65 12 0 0 0 0 0 Sahevgunj 0 2 1.5 0 0 0 0 0 Madyaharsahi 0.5 0.5 0.5 0 0 0 0 0

Kaptangunj 0.5 1 0.5 0 0 0 0 0 Total 1601.5 40219 102 31015 10000 1200 10 30


93. Table 3.9 shows the estimated loss of household goods. The estimated

total number of losses of, bed, closet, radio, television, cycles and motor

bikes was 3288, 1075, 1490, 225, and 3150 respectively. Those losses were

confined to three VDCs. In addition to these, 8 rice mills and 23 seller

mills were damaged.


50

Table 3.9: Loss of household goods in number

Name of the VDCs Khat Daraj Radio TV Cycle Motor bike

Haripur 75 25 40 10 50 1

Shreepur Jabadi 3000 1000 1400 200 3000 10

Paschim Kusaha 150 50 50 15 100 0

Ghuski 30 0 0 0 0 0

Basantapur 30 0 0 0 0 0

Laukahi 0 0 0 0 0 0

Narsimha 0 0 0 0 0 0

Ramgunj Sinuwari 0 0 0 0 0 0

Devangunnj 0 0 0 0 0 0

Sahevgunj 3 0 0 0 0 0

Madyaharsahi 0 0 0 0 0 0

Kaptangunj 0 0 0 0 0 0

Total 3288 1075 1490 225 3150 11


94. One estimate of the loss/damage incurred in monetary value shows that

there was a loss of about 3773.6 million rupees (Table 3.10). Land value

comprises nearly 64% of the total loss, followed by livestock, food, crops

and houses. This estimate is based on the losses in only four VDCs and

did not incorporate the loss of other household goods, infrastructure and

services. So, the total loss would seem to exceed this estimate.

Table 3.10: Estimated monetary loss

Properties Loss in Rs % House and shed 60454080 1.6 Land 2422400375 64.2 Livestock 319247508 8.5 Crops 176641475 4.7 Food 190844448 5.1 Total 3773603836 100.0

95. Table 3.11 shows the estimated loss of infrastructure such as road, bridges

and culverts. About 7 km of metalled road, 126 km of graveled road, 131

km of earth road and 82 km of trails were damaged. Similarly, 6 bridges

and 67 culverts were also damaged by the flood.


51

Table 3.11: Loss/damage of roads and trails

Road (km)

SN

Name of the VDCs Metalled Graveled Earth Total

Trail (km)

Bridge (no)

Culvert (no)

1 Haripur 4 15 25 44 5 1 12 2 Shreepur Jabadi 3.1 35 20 58.1 10 2 35 3 Paschim Kusaha 0.2 28 15 43.2 8 3 6 4 Ghuski 0 11 15 26 7 0 4 5 Basantapur 0 3 6 9 8 0 2 6 Laukahi 0.1 1.5 2 3.6 0 0 1 7 Narsimha 0 8 8 16 7 0 2 8 Ramgunj Sinuwari 0 3.5 10 13.5 10 0 0 9 Devangunnj 0 14 16 30 9 0 1

10 Sahevgunj 0 2 4 6 4 0 2 11 Madyaharsahi 0 2 3 5 4 0 1 12 Kaptangunj 0 3 7 10 10 0 1 Total 7.4 126 131 264.4 82 6 67


96. Table 3.12 shows the losses of other infrastructure such as transmission

lines, canals, public buildings and temples. About 117 km of transmission

line, 73 kms of canal, 19 public buildings and 26 temples were damaged

by the flood. Transmission lines and canals even in the downstream area

in the far south and eastern parts were damaged. Five towers of 132 kv

transmission line were damaged by the flood.

Table 3.12: Damage to infrastructure

SN Name of the VDCs Transmission line Canal Public Building Temple

1 Haripur 24 9 4 0 2 Shreepur Jabadi 60 8 12 26 3 Paschim Kusaha 15 8 3 0 4 Ghuski 0 10 0 0 5 Basantapur 0 2 0 0 6 Laukahi 0 2.5 0 0 7 Narsimha 0 6 0 0 8 Ramgunj Sinuwari 6 7 0 0 9 Devangunnj 12 10 0 0

10 Sahevgunj 0 4 0 0 11 Madyaharsahi 0 5 0 0 12 Kaptangunj 0 1.5 0 0 Total 117 73 19 26



52

97. The flow of people and goods ceased completely for a period of between

30 to 220 days. Previously more than 3600 vehicles used to shuttle every

day on the East-West Highway.. Similarly, the supply of drinking water

and electricity was completely stopped for up to 220 days in many places.

Industries were closed for up to 220 days (Table 3.13).

Table 3.13: Number of days when the flow of goods and services were closed

SN Name of the VDCs Traffic flow

Water supply Electricity Trade Industry

1 Haripur 180 200 220 150 150 2 Shreepur Jabadi 180 200 220 150 220 3 Paschim Kusaha 200 200 200 200 200 4 Ghuski 200 0 20 30 20 5 Basantapur 30 0 15 30 15 6 Laukahi 220 7 30 30 30 7 Narsimha 30 15 15 30 15 8 Ramgunj Sinuwari 45 15 15 30 15 9 Devangunnj 45 15 15 30 15

10 Sahevgunj 40 15 15 30 15 11 Madyaharsahi 40 15 15 30 15 12 Kaptangunj 45 15 15 30 15


3.3 Breach Repair

3.4 Conditions of the Spurs and Maintenance

98. The assessment team undertook a detailed assessment of the

embankments and spurs. As per the team’s assessment, spurs from

0.0Km to 10.6 KM2 from the border, there is a need to bring the spurs to

their design length to address the shorter term problem. However, there

is a need to develop a physical model to undertake detailed analysis and

build spurs. The pitching of the nose is damaged in most of the spurs and

the nose protection using gabion-wire boxes filled with boulders are

essential.

The breach repair work repair is ongoing between 10.7 km and 13.4 km.


53

99. For spurs from 14.1 km and 14.5 km, there is a need to restore the nose,

apron and shank slope. There is a need extend the length of the spur to

their design length of 150m and providing proper armoring of gabion

boxes.

100. On spurs between 14.5 and 15.3 km, there is a need to construct a new

spur, possibly extending up to 180 m. It should be noted that this will

only be a temporary measure and should be confirmed with detailed

model testing. Spur at 16.8 km appears damaged and there is need to

extend the spur to its design length, properly armor and construct nose,

shank, and launching apron.

101. Spurs from 18.81 km and 19.52 km need urgent attention and these need

to be repaired with priority. Procupines are provided but they need to be

very urgently repaired before the onset of the monsoon. Several of the

nuts and bolts of the porcupines have gone missing. This place preferably

the river is diverted away from its current flow direction. There is a need

also to provide geo-tubes.

102. The Prakashpur/Rajapur section of spurs (23.1 k m and 23.52 and 24.45

km to 27.1 km) also need to be repaired immediately before the onset of

the monsoon. The spurs require laying of geotubes especially along the

embayed section in between the spurs. The repair work needs to be

carried out without delay and there is no need to wait until the results of

the model tests become available. All the spurs need to be extended to

their design lengths and efforts should be made to channelize the flow of

the Koshi away from the embankment.

103. Construction of new spurs at suitable locations and rehabilitation of

damaged spurs is also proposed to protect the existing and the newly-

constructed embankments, especially from the two spots that the team

has identified as dangerous (along Prakashpur and Rajabas).

104. The western embankment is extensively encroached. At places, local

people have constructed animal pass and the spurs are being put in


54

various uses. Apparently, the east-ward shifting of the river has made

people complacent about the possibility of flood. There is a need to

quickly address this situation and remove uses of

3.5 Rehabilitation Works in Progress

105. Following the breach, remedial works have been undertaken to

reconstruct the embankment between chainages 12.100 km to 13.400 km.

To facilitate this work, the Koshi River has been diverted westwards

through the construction of a series of three cofferdams. The river

diversion has been very effective.

106. The new embankment between chainages 12.100 km to 12.900 km is

designed with a slope of 1:2 on the river side and 1:5 on the country side.

Revetments are being placed over geotextiles at the embankment toe on

the river side to protect it from scouring. The designed section and

protection works for the embankment appear adequate.

3.6 Assessment of Breach Flood Risk

107. It is very difficult to determine the probability of breaching and the

direction of the water flow and its magnitude, without making a detailed

investigation of the materials and geo-hydrodynamics of the river

channel as well as the terrain of the piedmont. However, an attempt has

been made to identify potential sites where breaching could occur after a

short field observation and discussions with the local people. Three sites –

Prakaspur, Rajbas and Pulthegaunda were identified as potential sites for

breaching, in the absence of effective protective measures (Figure 3.1).


55

Figure 3-1: Potential Breach Points and Flow Paths


56

Figure 3-2: Google Earth Image showing concentration of flow upstream of the breach (1=Current Breach, 2= Prakashpur, 3= Rajabas and 4=Pulthegaunda)

2

3

1

2

3

4


57

108. The flow path was determined based on the gradient of the terrain as

indicated by the contours. Another consideration in determining the flow

path, particularly from Pulthegaunda, was the old channel of the Koshi

River. The old channel of the Koshi River has been traced to about 35 km

east from the Barrage (Gole and Chitale, 1996 cited in Dixit, 2009). It is in

this context that the flow is likely to follow the old channel.

109. As can be seen in Figure 3.2 above, similar concentrations of river are

clearly visible on the embankment.

3.7 Exposures to Potential Risk

110. Identification and quantification of the elements exposed have been based

on two sources of information – topo sheet maps and field surveys at

VDC level. The analysis is made at VDC level. The breach floods of 2008

affected 12 VDCs with a total population of 98,680 according to the

Population Census of 2005. The number of VDCs likely to be affected

from the Prakashpur site are 20 (12+8), which also includes VDCs located

in the downstream area with a population of 163,846. Likewise, the

number of VDCs likely to be affected due to the breach at Rajbas is 29

with a total population of 259,646. Inaruwa, the district headquarters of

Sunsari District is likely to be affected. The number of VDCs likely to be

affected due to breaching at Pulthegauda is 54 with a total population of

652,811. Biratnagar is likely to be affected in this scenario (Table 3.1 and

Figure 3.14). The cultivated land likely to be affected ranges from 360 sq.

km from the potential Prakashpur breach to 436 sq. km from Rajbas and

826 sq. km from Pulthegaunda. The total area likely to be affected ranges

from about 44.6 sq km of forest, 14.5 sq. km of plantation area, 25.2 sq. km

of grassland and 2.5 sq. km of built up areas. About 677 km of road,

including 61 km of highway is likely to be affected. There are more than

100 ethnic groups living in this area. The major ethnic groups in

population are Muslim, Tharu, Bahun, Chhetri, Yadav, Koiri, Mushahar,


58

Jhagar, Newar, Teli, Dhanuk, Rajbansi, Kewat, Rai, Baniya, Mallaha,

Marwadi, Haluwai, Gangai and Bantar (Figure 3.3).

Figure 3-3: Area under risk and major ethnic groups


59

Table 3.14: Elements exposed to the potential risk of breach flood in Koshi

Likely to be affected

Elements exposed Affected Prakashpur Rajbas Pulthegauda Total

No of VDCs (no) 12 8 9 25 54 Population (no) 98680 65166 95900 393065 652811 Land (sq. km) 192.76 113.52 188.43 478.63 973.34 Cultivated 171.86 88.50 172.46 393.37 826.20 Forest 0.33 3.99 7.68 32.64 44.64 Plantation 3.13 2.30 4.01 5.10 14.54 Bush 0.02 0.23 0.03 0.70 0.98 Grassland 4.01 8.87 0.15 12.12 25.15 Built up area 0.03 0.00 0.38 2.13 2.54 Barren land 0.58 0.08 0.12 3.16 3.95 Sand and gravel 3.83 4.61 0.42 15.80 24.66 Swamp 3.15 0.31 0.20 0.31 3.96 Water body 5.81 4.62 2.98 13.30 26.72 Road (km) 133.94 82.21 70.83 389.79 676.77 Highway 22.75 1.16 3.8 33.23 60.94 Other roads 111.19 81.05 67.03 356.56 615.83

Source: Compiled from different sources – population from Population Census, 2001; landuse and road from topo sheet maps (1:25000) published by the Survey Department, GoN.

111. A survey of 17 village development committees located in areas adjoining

stretches of the Koshi River, shows that nearly 41% of the total land area

in these VDCs is likely to be severely affected. About 28% area is likely to

be moderately affected from the breach floods (Fig 3.3 Table 3.15). Nearly

42% of households and 43% of the population are living in areas which

are likely to be severely affected by the flood. The percentage of

households and portion of the population living in areas which are likely

to be moderately affected is 30% each. There are many settlements on the

island within the distributaries of the Koshi River and within the

embankments in two of the VDCs- Prakashpur and Manhendranagar.

These settlements are located in high risk areas. There are 152 families in

Mahendranagar and 350 households in Prakashpur living in a high risk

area.


60

Figure 3-4: Risk classification of the Koshi Basin below Chatra until the Barrage

Table 3.15: Area under different levels of risk and population

Land Household Population Level of Risk

Area (Bigha) % Number % Number % Severely 33310 41.0 12651 42.2 75241 43.4 Moderately 22433 27.6 9122 30.4 51853 29.9 Slightly 25446 31.3 8222 27.4 46430 26.8 Total 81189 100.0 29995 100.0 173524 100.0


112. Nearly 40% of the total cultivated land, 38% of vegetable and fruit

growing areas and 48% of forest land are likely to be affected severely

from the flooding. About 29% of the total cultivated land and 28% of the

vegetable and fruit growing areas are likely to be moderately affected.

The percentage of cultivated land with slight risk of flood is less than 32%

(Table 3.15).


61

Table 3.16: Area under different levels of risk by land types

Cultivated land Orchard Forest Level of Risk

Bigha % Bigha % Bigha % Severely 26086 39.4 506 37.7 164 48.1 Moderately 19353 29.2 369 27.5 95 27.9 Slightly 20743 31.3 467 34.8 82 24.0 Total 66182 100.0 1342 100.0 341 100.0


113. Table 3.16 clearly shows that nearly 46% of pakki houses and 44% of

kachhi houses are located in areas which are likely to be severely affected

by the flood. About 33% of pakki houses and 29% of kachchi houses are

located in areas which are likely to be moderately affected. Only 21% of

pakki houses and 27% of kachhi houses are located in relatively safe

areas.

Table 3.17: Number and percentage of houses located with different levels of flood

risk

House Pakki House Kachhi Level of Risk Number % Number % Severely 935 46.2 11310 43.9 Moderately 658 32.5 7474 29.0 Slightly 429 21.2 6967 27.1 Total 2022 100.0 25751 100.0


114. Nearly 37% of cattle, 45% of buffaloes and 46 percent of goats are owned

by the households who are living in areas which are likely to be affected

severely by the flood. Only 26% of the cattle, 27% of the buffalo and 23%

of the goats are reared by households living in relatively safe sites (Table

3.18).


62

Table 3.18: No. and percentage of livestock owned by households with different

levels of flood risk

Cattle Buffalo Goat Level of Risk Number % Number % Number % Severely 20263 36.7 22282 45.0 27821 45.7 Moderately 20656 37.4 14045 28.4 19002 31.2 Slightly 14301 25.9 13198 26.6 14112 23.2 Total 55220 100.0 49525 100.0 60935 100.0


115. Nearly 41% of the total paddy production, 49% of maize, 49% of wheat

and 51% of millet are from areas which are likely to be severely affected

by the flood. Only 30% of the total production of paddy, 26% of maize,

wheat and millet are from areas which are relatively safe from flood

hazard (Table 3.19).

Table 3.19: Major crops with level of risk

Paddy Maize Wheat Millet

Level of Risk Quintal % Quintal % Quintal % Quintal % Severely 403217 41.4 162107 48.7 178813 48.8 8065 50.5 Moderately 274622 28.2 84622 25.4 92290 25.2 3810 23.9 Slightly 296495 30.4 86468 26.0 95031 26.0 4095 25.6 Total 974334 100.0 333197 100.0 366134 100.0 15970 100.0


116. Table 3.20 shows the number and percentage of public buildings and

other infrastructure located in areas with different levels of flood risk.

Nearly 48% of school buildings, 45% of office buildings, 47% temples,

48% of rice mills and 44% of tube wells are located in areas which are

likely to be affected severely by flood hazard. Only 24% of schools, 13%

of office buildings, 26% of temples, 29% of rice mills and 24% of tube

wells are located in relatively safe sites.


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Table 3.20: Number and percentage of public buildings, industries and structures

by the level of flood risk

Schools Office building Temple Rice mills Tube well Level of Risk

Number % Number % Number % Number % Number % Severely 64 48.1 38 44.7 99 47.4 59 48.4 11468 44.2 Moderately 37 27.8 36 42.4 56 26.8 28 23.0 8176 31.5 Slightly 32 24.1 11 12.9 54 25.8 35 28.7 6280 24.2 Total 133 100.0 85 100.0 209 100.0 122 100.0 25924 100.0


117. Table 3.21 shows the distribution of infrastructure in areas with different

levels of flood risk. Nearly 67% of bridges, 54% of culverts, 46% of

transmission lines, 41% of irrigation canals, 69% of highways and 43% of

road networks are located in areas which are likely to be severely affected

by flood hazard. Only 16% of bridges, 24% of culverts, 28% of

transmission lines, 3% of highway lengths and 29% of the road networks

are located in relatively safe sites.

Table 3.21: Number and percentage of items of infrastructure by level of flood risk

Bridges

Culv ers

Transmission line

Canals

Highways

Other roads

Lev el of Risk Number % Number % km % km % km % km % Sev erely 4 66.7 114 54.0 226 45.6 131 40.9 22.5 69.2 354 42.8 Moderately 1 16.7 47 22.3 130 26.2 84 26.2 9 27.7 235 28.4

Slightly 1 16.7 50 23.7 139.5 28.2 105.2 32.9 1 3.1 238 28.8 Total 6 100.0 211 100.0 495.5 100.0 320.2 100.0 32.5 100.0 827 100.0


118. It is evident that nearly two thirds of land, property and infrastructure is

at high risk of hazardous flooding. This fraction is likely to be lost or

damaged by the flood.

3.8 Local capacity to cope with flood risk

119. It is evident that nearly two thirds of land, property and infrastructure is

at high risk of hazardous flooding which means that they are likely to be

lost or damaged by the flood. Attempts have been made to assess the

local capacity to cope with the potential risk of flood based on four


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indicators – major occupation of the household, size of landholding, level

of income and food sufficiency. The major source of income of 64% of

households is agriculture followed by labor, trade and remittance (Table

3.22)

Table 3.22: Number of households by major occupation

Occupation Household % Agriculture 19698 64.4 Trade 2304 7.5 Labor 6185 20.2 Service 745 2.4 Remittance 1533 5.0 Other 110 0.4 Total 30575 100.0


120. Many households depend on agriculture for their livelihoods. But the size

of their land holdings is rather small. Nearly 70% households are either

landless or marginal farmers with less than one hectare of cultivated land

(Table 3.23). Only 5% of households have a landholding size more than 3

ha and are capable of receiving cash earnings from agricultural products.

Table 3.23: Number of households by size of landholding

Size of landholding Household % Landless 2449 8.0 Marginal (<1ha) 18988 62.1 Small (1-3ha) 7426 24.3 Medium (3-5ha) 1469 4.8 Large (>5ha) 243 0.8 Total 30575 100.0


121. The average annual household income among 15% of households is less

than NRs. 25,000 which is about 4 -5000 rupees per person (Table 3.24).

More than 75% of households have an annual income of less than

100,000Rs which is about 18,000Rs per person. Only 7 % of households

have an annual income of more than 200,000Rs.


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Table 3.24: Number of households by annual income category

Income category (NRs.) Household % <25000 4506 14.7 25000-50000 7782 25.5 50000-100000 10882 35.6 100000-200000 5323 17.4 >200000 2082 6.8 Total 30575 100.0


122. The production generated by a large number of households is not

sufficient to fulfill their own food requirements. Nearly 38% of

households have their own produce which is sufficient only for six

months (Table 3.25). Only 20% of households do have enough production

with surplus for sale.

Table 3.25: Number of households by level of food sufficiency from own production

Food sufficiency Household % < 3 months 7136 23.3 3-6 months 4618 15.1 6-9 months 5667 18.5 9-12 months 7110 23.3 Surplus/sale 6044 19.8 Total 30575 100.0


123. It is clear from the discussion above that the capacity of local people to

cope with flood risk is very low. Because the majority of people are

landless, marginal and small farmers, they have a low level of income

and they have a severe food deficit.

3.9 Flood Risk Management

3.9.1 The August 2008 breach flood

124. Rescue and relief activities were carried out immediately after the

breaching of the embankment. Since the breaching occurred in the

daytime at 12.55pm and the potential of risk to the local population was


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communicated early in the morning, people left the area with their

belongings before the breach flood reached to their localities. So the

number of deaths due directly to the flood was only one. The number of

internally displaced families was 7306 with a total population of 41,340.

Among these internally displaced families about 72% lived in camps, 3%

in host families and the remaining 25% in their original home community.

The statistics for the internally displaced people still need verification

because of the reporting by members of the same family in different

camps on the one hand and non-reporting by many people on the other.

The recording and verification work is ongoing.

125. This survey shows that there are 34 camps distributed in different areas

(Figure 3.5). Eight camps located by the western bank of the river have

been vacated. The Indians living in these camps returned home by taking

a sum of Rs. 4,500 provided by the government. However, the displaced

Nepalese people have joined other camps located in the Sunsari district.

The details of households and population in these abandoned camps are

given in Table 3.26.


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Figure 3-5: Shelter Camps in the Area

Table 3.26: Number of households and population in vacated camps located on the western bank of Koshi River.

Camp Id Household Population A 463 2993 B 344 1512 c1 373 2000 c2 78 461 c3 102 558 c4 209 1135 d1 641 3781 d2 426 2470 Total 2636 14910


126. A total of 26 existing camps were surveyed during the field work. There

are a total of 44466 internally displaced people in these camps. The size of


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camps in terms of the number of displaced people living in the camps,

ranged from 395 people to 3487 people, with an average of 1710.There are

8 camps with a population size of less than 1000, 8 between 1000-2000, 9

between 2000-3000, and only one with more than 3000 (Table 3.27).

Table 3.27: Number of camps by size of population

Population size Number of camps Below 1000 8 1000-2000 8 2000-3000 9 > 3000 1 Total 26 Source: Field Survey, February, 2009

127. Table 3.28 shows the demographic characteristics of internally displaced

people living in the surveyed camps. The female population exceeds the

male population in these camps. Nearly14% are children and 0.3% are

disabled.

Table 3.28: Number of people by sex and other status

Number % Male 21541 48.4 Female 22925 51.6 Total 44466 100.0 Children 6322 14.2 Disabled 142 0.3 Source: Field Survey, February, 2009

128. Table 3.29 shows the economic status of internally displaced people.

Nearly 45% of the total number of families who answered about

ownership of land are landless while 55% of families do have their own

land. Many families belong to marginal and small farmers. Only 2%

families do have a large size of landholding and they rent out their land.


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Table 3.29: Number of families by ownership of land

Status Number % Landless 1355 45.1 Landowner 1651 54.9 Not Stated 4235 58.5 Renters 65 2.2

129. Table 3.30 shows the place of origin of the internally displaced people

living in these 26 camps. These places are Haripur, Shreepur, Kusaha and

Laukahi VDCs in the Sunsari District in Nepal and nearby areas from

India. The average family size of these internally displaced people ranged

from only 5.3 to 6.7 members. Out of a total of 44,466 people living in the

camps 32% are from Haripur, 47% from Shreepur, 18% from Kusaha and

1.6% from India.

Table 3.30: Number of household and population living in the camps by the place

of origin

Household Population Average size % Haripur 2530 13454 5.3 32.7 Shreepur 3611 21459 5.9 46.6 Kusaha 1373 8097 5.9 17.7 Laukai 100 665 6.7 1.3 India 127 791 6.2 1.6 Total 7741 44466 5.7 100.0 Nepal 7614 43675


130. Table 3.31 shows the service infrastructures available in these camps.

Drinking water and toilet facilities are available in all the camps.

However, there is no health care, child care or education facilities in

many of the camps. There is also a lack of provision of security in the

majority of the camps. Lack of security for adolescent girls and the fear of

women and children being trafficked across the border and fear of

communal confrontation are some of the issues associated with the poor

security provision in many camps.


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Table 3.31: Number of camps with/without service facilities

SN Type of facilities With Without Total % With

1 Drinking water facil ity 26 0 26 100.0 2 Toilet facility 26 0 26 100.0 3 Bathroom 23 3 26 88.5 4 Health care service 19 7 26 73.1 5 Child Development Care Centre 17 9 26 65.4 6 Education facility 11 15 26 42.3 7 Security provision 14 12 26 53.8 8 Information Centre 11 15 26 42.3 9 Electricity 2 24 26 7.7


131. An attempt was also made to estimate the value of different major items

distributed within the camps. These values were based on the

expenditure made during one month before the survey month. Nearly

29% is spent on clothes followed by food, tent construction and

maintenance, utensils and training activities (Table 3.32).

Table 3.32: One month’s expenditure on different items in the camps

Items No. of people benefited Value (Rs.) % Value

Food 43357 57839911 26.84

Lito (baby cereal) 806 77600 0.04

Cloth 43357 63401143 29.42

Medicine 43357 1439772 0.67

Tent 43357 54763145 25.41

Toilet 24966 5057284 2.35

Chulo 395 156400 0.07

Drinking water 43357 3598665 1.67

Container 2560 18275 0.01

Utensils 43357 11330918 5.26

Training 2195 10286808 4.77

Cash 41732 7548100 3.50

Total 332796 215518021 100.00


132. Table 3.33 shows the sufficiency in the distribution of different items

requested by different camps. Food, clothing, tents, utensils and cash are


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not sufficiently distributed in many camps and the supply of drinking

water, medicine and training is similarly not wide. People have been

suffering from many diseases such as coughs, fever, diarrhea, eye

infections, skin diseases, measles and acute respiratory illnesses. More

than 80% cases are of diarrhea. It was also reported that the size of clothes

and utensils distributed has not been according to their needs. They are

either too small or too big.

Table 3.33: Number of camps reporting sufficiency in the distribution of goods

and services

Items Yes No Food 3 23 Clothing 2 24 Tent 2 24 Medicine 18 8 Utensil 4 22 Drinking water 20 6 Training 24 2 Cash 2 24


133. Many international/national/local institutions are involved in relief and

rehabilitation activities for the internally displaced people (Table 3.34)

Their efforts are confined to registration, verification and distribution of

goods and services. No one is actively involved in the rehabilitation of

degraded land by removing sand. The layer of sand over the cultivated

land in many places is 3-6 ft. In the season of strong winds, the sand

deposited in the cultivated land could create health hazards in the area.


72

Table 3.34: International/National Agencies Involved in Relief by Sector

Sector Institutions involved

Food WFP, NRCS, SC, LWF, FAO, DEPROSC, Concern, WVI, UNICEF,

Clothing Oxfam, KVS, Care Nepal, NRCS, IOM, EV, SC, WEL, LWF, UNICEF, Rotary, WVI, Nepal Paribatan

Tent Rotary International, Oxfam, KVs, NRCS, Care Nepal, EU, LWF,

UNICEF, WEL, KODEF Nepal, IOM, Action Aid Medicine NRCS, Oxfam, KVS, DPHO, Care Nepal, WEL, UNICEF

Utensil NRCS, Care Nepal, KVS, Oxfam, IOM, WEL, Rotary Club

Drinking Water DWO, Caritas, RRN, Oxfam, KVS, NRCS, UNICEF, WEL, Paribartan

Nepal, CSDC

Training Rotary International, DPHO, Oxfam, KVS, NRCS, WASH, WEL, Paribartan Nepal, OHCHR, Plan Nepal, Action Aid

Cash District Disaster Committee, CDO Office

Chulo Care Nepal

Litopitho WFP, DEPROSC, CONCERN, SC

Toilet Oxfam, KVS, Sabal Nepal, WEL, NRCS, UNICEF, LWF

CDO=Chief District Office(r) CSDC = Community for Social Development Centre DEPROSC = Development Project Service DPHO=District Public Health Office DWO=District Water

Office FAO= Food and Agriculture Organization IOM = International Organization for Migration KVS = Koshi Victim’s Society, LWF = Lutheran World Federation NRCS = Nepal

Red Cross Society OHCHR= Office of the High Commissioner for Human Rights SC =

Save the Children UNICEF = United Nations Children’s Fund WFP = World Food

Programme WVI = World Vision International

134. Table 3.35 shows the willingness of the people living in the camps to

return to their homes. Very few people are willing to return to their

home. The figure is only 13%. Nearly 87% of the total internally displaced

people living in the camps are not willing to return their homes 3. Many of

them are landless and marginal farmers. There is still a fear of the danger

of breach flooding from the same site. Furthermore there is a wide spread

belief that the government will provide compensation. Many families

have been maintaining multiple households to take advantage of the free

distribution of food and other household items in the camps. They have

demanded land and other support for resettlement and identified two

areas for resettlement: One is located in Singiya VDC and another is

located in Mahendranagar VDC. Both areas are on public land covered

with forest.

3 Previous study showed that more than 60% families were willing to return their home.


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Table 3.35: Number of people willing/not willing to return home

Willingness Number % Willing to return home 5708 12.8 Willing to stay in camp 38758 87.2 Total 44466 100.0


Figure 3-6: Area Covered by Sand and Water

135. The Government has classified the internally displaced people into three

categories – red, yellow and green. People belonging to the red category

are those whose lands are covered with a thick layer of sand or have been

scoured by the flood. (fig 3.6) The estimated families in this category are

1500. There are two alternatives for the rehabilitation of this group – the

rehabilitation of their land by removing sand or resettlement in other


74

areas. No collective or institutional effort has been made in connection

with the rehabilitation of damaged land till now. There was an

opportunity to rehabilitate the sand deposited area if proper care had

been made for cultivation when there was enough moisture in the soil, by

providing seeds, fertilizer and technology for the landowners.

136. The government has issued a package of Rs. 50,000 per family to return

internally displaced people in the yellow and green category to their

homes. However, the demands of internally displaced people including

the leaders of many political parties were higher than this. They

demanded land for resettlement. The Jhumka Agricultural Farm is

another alternative for the resettlement of the internally displaced people.

However, the size of land available is too small to accommodate all the

displaced people. This issue has been politicized and the large

landholders who belong to different political parties have asked others

not to leave the camps hoping that they could receive compensation for

all their land from the government through their collective voice.

3.10 Preparedness

137. Most of the activities have been focused on rescue and relief activities.

Only a few activities have been carried out for rehabilitation and

preparedness. The provision of NRs. 50,000 package for Nepalese

displaced families and NRs 4,500 for Indians has been made to encourage

people to return home. The capacities of many internally displaced

people has been improved through different types of training. However

no effort has yet been made for the rehabilitation of damaged land and

resettlement or other alternatives for those who are unwilling to return

home.

138. It has been planned for the maintenance of all those spurs which are

shortened due to toe cutting by the river. It was reported that the

proposed plan i.e. the addition in length by 100m in the existing spur in

many places is not enough to reduce the risk of beach.


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139. Improvement in the road network- 23 km of the Jhumka-Chatra road, 12

km Dharan-Chatra road, Kanchanpur-Fattepur road and the Inaruwa-

Jalpapur-Dewangunj road and the provision of a ferry with a maximum

capacity of transporting 20 tons at a time, are some of the major activities

performed for flood preparedness. Keeping in view the magnitude of the

vehicular flow (1800 one way traffic per day), the provision of a ferry is

not enough. There is a need to construct a permanent bridge for better

preparedness.

140. Local people including political parties at a local level are not well aware

of the need of for preparedness activities. They often care for fulfilling

immediate needs. During the discussion, it was reported that the

investment in improvement in roads is a waste of resources. They

demanded that investing that resource for the rehabilitation of displaced

people should be a priority rather than spending on road improvement.

It is in this context that efforts should be made to make local people

aware of the importance of flood preparedness activities and the

development of a preparedness plan by involving them, in order to

reduce and manage the risk of flood hazard in the future.

3.11 Flood Fighting and Preparedness ( FF&P)

141. The assessment revealed that there is no organization responsible for

flood fighting and preparedness. There is no preparedness plan in place.

Notwithstanding, there is a mechanism that exists to undertake relief

measures after a disaster has already occurred. A large gap exists in terms

of organization, especially when it comes to coordination. The

Government of Nepal (GoN) has mandated the Department of Water

Induced Disaster Prevention (DWIDP) under the Ministry of Water

Resources (MoWR) to deal with water induced disasters. In the Koshi

case according to the Nepal-India agreement, the Government of India

(GoI) is responsible for all infrastructural works including repair and

maintenance from Chatra to the Indian Border. This makes DWIDP’s role


76

almost none existent in the area from the Chatra confluence to the

Barrage. The GoN has mandated the Department of Hydrology and

Meteorology (DHM) for hydrological and meteorological data collection,

including early warning and flood forecasting on a nation-wide basis, but

the DHM has very limited instrumentation in the Koshi river basin.

Needless to say the establishment of an Early Warning System (EWS) is

one of the prime requirements for flood fighting and a preparedness plan

to save lives and properties on n both the Nepali and Indian side. The

assessment clearly demanded that a fully- fledged EWS is established on

a priority basis as a non-structural measure in the Koshi Basin.


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4 CONCLUSIONS AND KEY ISSUES

4.1 Introduction

142. As requested by UNCT in Nepal, UNESCO fielded a team of government

officers from Nepal and experts from both India and Nepal. The Team

was assigned to undertake a Rapid Hazard Risk Assessment. The Team

has just completed their field work. The following conclusions can be

drawn from the team’s findings:

143. The river has been diverted within the course of the designed

embankment. A very dry winter in Nepal has helped the breach repair.

144. The construction work is going on satisfactorily and the observation by

the team’s structural engineer has been very positive on the quality and

pace of construction. The efficiency of the Indian engineers in

spearheading the task deserves appreciation.

145. Having said the above, if analysis is made of the pre-breach conditions of

2008, there are several conditions that still exist that indicate the existence

of risk. The following paragraphs briefly evaluate these threats:

4.2 Technical Issues:

146. All the spurs along the embankment require major repair work. The

rebatement along the sides of the spurs are almost non-existent. Also

most of the noses and the aprons of the spurs are eroded. As the Team’s

analysis has established that the breach of 2008 had principally occurred

due to the spur failure, followed by the embankment failure, there is a

need to consider restoring spurs to their original design lengths.

147. The team identified that all spurs have been shortened on average by 20-

70 meters and they need to be restored to their design length and their

noses and launching aprons need to be repaired. The repair work falls

short of what is considered adequate.


78

148. The condition of the spurs and the way they stand is not sufficiently

strong to withstand floods of a higher magnitude. As per the Team’s

observation the 2008 flood was only about 80 percent of the average high

flow in Koshi. It was not one of the critical historical hydrological events

which caused breaches.

149. The Teams have identified three places upstream of the current breach

requiring immediate attention, as the constricted flow of about 75% of the

total flow is flowing only 70 meters away from the embankment. These

spots in Rajabas, Prakashpur and Pulthegaunda need immediate

attention as a breach in either of these spots could cause massive

destruction in the area compared to the 2008 breach.

150. The geomorphology of the river is poorly understood and as the world’s

second largest silt carrying river, the role of silt in bank erosion needs

further study.

151. The basin is also prone to danger due to GLOF-related events. Although

the problem will not be so much about water but about the silt that the

GOLF can potentially bring down to the alluvial fan. This can

dramatically decrease the cross-section of the river, ultimately leading to

possible over-topping of the embankment.

152. The river is still flowing along the eastern embankment in a narrow

channel highly prone to erosion. The Google image of 2004 clearly shows

the concentration of flow, which still exists.

153. The trees in between the spurs inside the embankment in the Koshi wild

life reserve can act as attracting spurs upon their natural felling due to

smaller floods.

154. The western embankment is in relatively worse shape and if the river

course changes its course towards the western bank, a bigger catastrophe

could occur.

155. The use of latest technology and mathematical modeling is lacking (or

reportedly on-going), which could alternatively justify constructing


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frequent shorter length spurs. The shorter length flood could facilitate

maintenance and flood fighting measures quickly as practiced in the

Sunsari Morang command area development.

4.3 Institutional Issues:

156. The maintenance of the embankment is guided by a bilateral treaty and in

this treaty it is highly desirable that the role of Nepal should be

enhanced. Reportedly, this has lead to deliberate delays and/or

obstruction of work.

157. Several forms of communication failures, similar to those that existed

before the 2008 breach, still exist amongst the various agencies involved

in flood risk reduction.

158. Transparency in monitoring of the embankment and spurs still has room

for improvement. Information on regular periodic maintenance and

repairs needs to be properly archived. At least on the Nepal side, no

such archive exits.

159. The role of the authority that oversees wildlife reserve of Koshi may be

looked at again and revisited. Reportedly, the monitoring of spurs was

hampered due to indifferent behavior and neglect. This also has a bearing

on clearing of trees on the river-side of the embankment.

160. There appears to exist a focus on flood fighting and not so much focus on

the repair and maintenance of the spurs. Obviously, the “wait and watch”

approach is taking prevalence over prompt repairs and maintenance.

4.4 Social Issues

161. There is a need to look again at the broader picture of the basin and the

application of non-structural approaches, such as erosion control at the

source of the river upstream are essential.

162. The 2008 breach displaced nearly 7000 families in which majority are

landless and poor farmers. Their vulnerability to flood hazard is rather

high, thus their exposure to risk is also very high.


80

163. People's participation in the embankment repair and maintenance needs

to be improved by involving local people in the embankment repair,

maintenance and monitoring works.

164. The ownership of the embankment is the key and local people appear not

to own the embankment and spurs.

165. The team was informed of several problems regarding labor, which

existed just prior to breach. The team interviewed a few labor suppliers

and can conclude that such problems are still likely to occur.

166. The area suffers from Bandhs and strikes almost an every alternate day.

Such strikes can hamper repairs and maintenance and especially the flood

fighting effort, as it did in 2008.

4.5 Preparedness Issues:

167. The team observed that the basin does not have proper data collection,

information sharing and archiving arrangements. There is a need for

improvement vis-à-vis the application of new technology, real time data

collection, information archiving and processing.

168. There is a need to prepare hazard and risk maps and assessments which

can pay particular attention to the potential sites of embankment

breaching.

169. Since the coping capacity of local people is low, their capacity for risk

management needs to be enhanced through capacity development

interventions.

170. There is a need to develop a thorough calibrated model, either in

HECRAS or in MIKE Flood and the generation of finer resolution DEM,

and their application etc.

171. Despite the fact that the area is highly susceptible to flooding, the team

found no early warning system or flood warning system in the area.


81

172. There is a need to prepare “what-if” scenarios for the river. In this way

the flood issue scenarios can be best tackled and flood risk reduction

modality properly established.


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5 RECOMMENDATION FOR RISK REDUCTION

5.1 Improving preparedness

173. The embankment failure in the Koshi basin has provided sufficient reason to

justify the application of all forms of risk reduction strategies. There is a need

to avoid risk; develop people’s ability to live with risk; reduce risk; and

develop risk transfer mechanisms and schemes wherever possible.

174. The team used the UN/ISDR strategy to analyse the preparedness of the

Koshi region. No programme to reduce physical, social, economic and

environmental vulnerability through the enhancement of national and local

capabilities prevails in the area at all. People were observed occupying flood

plains as their permanent home for short-term economic motivations and

because of an over-reliance on the structural efforts put in place. From the

governments’ side inconsistencies remain in terms of the attention to short-

term emergency relief measures and very little long-term thinking or

investment in disaster preparedness, including that for institutional capacity-

building. As noted people’s involvement and role in disaster risk reduction

strategies is not apparent. Similarly, the broader context of disaster

mitigation at the basin scale exists only in concept and currently no solid

transboundary and basin-wide initiative exists for Koshi. This includes any

development of a participatory process on creating awareness, processing

and dissemination and for the development of empirical knowledge of risk.

175. The breach has provided a basis on which to conclude that there is a need to

undertake strategic risk preparedness in the area as a national priority with a

strong organizational and policy basis for implementation. For this, there is a

need to better identify, assess and monitor disaster risks and enhance early

warning. Suggested priorities for action could include: completing, updating

and disseminating risk maps. There is a need to increase the use of

knowledge, innovation and education to build a culture of safety and

resilience. Suggested priorities for action may include: providing readily

understood information on flood risks and protection options; capitalizing


83

upon local and traditional knowledge of flood risk; training key officials on

risk reduction; and making use of information and communication

technology; etc. This involves taking a very straightforward approach as

depicted in figure below:

Figure 5-1: Conceptual Approach to Koshi Flood Preparedness

176. This will further require an immediate review and the creation of a national

flood disaster preparedness plan, the establishment and regularly testing of

information systems; the promotion of dialogue and cooperative activities,

both between emergency management personnel and disaster risk reduction

personnel in India and also across the border.

5.2 Preparation of Flood Standing Order

177. This study has demonstrated that there is a need to prepare a detailed

standing order to deal with the flood. Floods in Koshi River, as an annual

event, regularly cause loss of life, damage to property and infrastructure, and

are often the cause of psychological and emotional disturbance. It is the poor,

forced by sheer necessity to occupy vulnerable flood prone areas constitute

the bulk of victims. It can be safely stated that reducing the flood damage

caused by annual Koshi floods increases social and economical prosperity of

the people of Koshi River Basin.


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178. Floods can neither be eliminated nor totally controlled and so efforts are to

be directed towards reducing flood vulnerability and mitigating the flood

impact through improved flood managements. After the emergence of Koshi

in the plain area the Koshi embankment has been the main protective device

against flooding for the last few decades however, the sustainability and

efficacy of massive embankment construction as a permanent flood defense,

especially where Koshi carries such a tremendous amount of sediment load is

a subject of serious debate and the debate has been aggravated more with the

2008 Koshi breach.

179. A non-structural approach to flood management lies in flood forecasting and

early warning system. Because of frequently recurring flood events people

have learned to live with these conditions and are inclined to stay with their

homes and protect their belongings. With an advance early warning system,

a significant reduction in losses can be obtained by taking protective and

preventive measures. A timely warning provides time for the disaster

services to best deploy their services.

180. The objective of establishing such a system would be to protect the

agricultural land and human settlements from flooding along the entire

Koshi basin with specific focus on the foothills and the low-lying areas on the

either side of the embankment. The value of flood forecasting increases as

the lead-time increases and hence effective and timely information

dissemination to those responsible for disaster management and then directly

to the people affected, would be likely to achieve a successful result.

5.2.1 Nepal-India History of Flood Forecasting Cooperation

181. It was agreed at the secretary level meeting between Nepal and India held in

Kathmandu on December 22, 1987 that Nepal and India would expedite the

implementation of facilities to be provided for an efficient flood forecasting

system on the major tributaries of the Ganga that flow from Nepal into India.

It was also agreed that Nepal would implement and maintain the system in

its territory and would accept the necessary equipment from India to


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implement the system expeditiously. In pursuance of this meeting, a high

level Indian delegation of technical officers, headed by the Member for (River

Management), the Central Water Commission, New Delhi, held further

discussions with the officers of the Government of Nepal in March 1988 and

identified 20 hydro-meteorological and 25 meteorological sites. A list of

additional equipment required to make these 45 stations fully operational

was also identified.

182. In May 1988 a subsequent secretary level meeting decided to form an expert

team to install a real-time data transmission system to India from selected

rain gauge and hydrological stations in Nepal. It was also agreed that on a

reciprocal basis, India would provide Nepal with hydrological data of rivers

entering India from Nepal, at two points downstream of the border. ,. It was

envisaged that the real time transmission of rainfall and hydrological data

from Nepal would help in increasing the lead time of the flood forecast

resulting in enhanced preparation time for evacuation and other preparatory

measures. This transmission of data is still continuing but the efficiency,

effectiveness and the benefits derived from this system are to be carefully

analyzed. The system as it is now carries almost no weight in terms of adding

any substantial improvement to the flood forecasting system of both

countries.

183. Moreover with the recent development in communication systems, wireless

data transmission is almost obsolete. There are several modern technologies

available which are automatic and robust and are highly reliable, based on

satellite technology and remote sensing systems. Therefore future action

should be directed to establishing a full-fledged flood forecasting system for

the Koshi Basin. It would consist of optimizing the hydrological and

meteorological observation network, ensuring sustainable operation of the

system and the establishment of early warning systems equipped with

modern technology capable of disseminating reliable flood information.

184. The Nepal-India Committee on Flood Forecasting prepared a draft Flood

Forecasting Network for the 7 major river basins of Nepal in July 2002. The


86

network for the Koshi River Basin is attached herewith. The line diagram of

hydrometric stations on the Koshi River and its tributaries in India is also

attached herewith (Figure . 5.1)

Figure 5-2: Line Diagram of Hydrometric Station on Koshi and its Tributaries in India

Sonbarsa G

R. DHANS

Kamtaul G D F

Balan H/W

Jainagar G D

Basua G F

Birpur G B

Banmankhi G D

R. FARIYANIDHAR

Kursela G F

Saulighat GD

Dhe

ngbr

idge

G

D Baltara

G D F

Jhanjharpur G D F

R.JHIM

R. KAMALA-BALAN

R. KAMALA R. B

ALA

N

R.

AD

HW

AR

A

R. K

OS

HI

Ekmighat G D F

Hayaghat GDF

Run

isai

dpu

GD

Benibad G D F

RIVER GANGA

Abbreviations used: G = Gauge D = Discharge B = Base Station for FF F = Flood Forecasting Station


87

Figure 5-3: Hydrometric and Precipitation Station in Koshi Basin


88

185. The draft observation station network prepared by the above committee

needs to be reviewed and optimized in the present context. The Department

of Hydrology and Meteorology is to be made responsible for establishing a

fully operational flood forecasting and early warning System. A wide

dissemination of information must be ensured and a Flood Disaster

Preparedness Plan (DPP) is to be put in place. The DPP is to be coordinated

by the Ministry of Home Affairs (MoHA) and the members should include

the DHM, DWIDP, other relevant central government agencies, local

government, local people, and NGO’s and INGO’s related with disasters. The

Early Warning System (EWS) is to be constructed in such a way that all the

people that come under the flood influence would be informed of the

potential danger in a timely manner. Warning Sirens are to be installed in a 1

km by 1 km grid and evacuation plans are to be prepared before the

monsoon. Large shelters are to be constructed for settling the evacuated

people. These shelters will be on the available highland and could be used by

a school or for some other fruitful purpose during the no-flood period.

5.2.2 Review of the existing hydrological and meteorological network

186. The DHM maintains 33 river gauging stations within the basin. Out of these

all 33 have a manual staff gauge, 23 have the facilities to make discharge

measurements from the cable-way and 14 stations have Automatic Water-

Level Recorder (AWLR) in which only 6 are functional. The water level is

observed only two times a day in all 33 stations. There are 19 climatological

and 55 rain gauge stations. The climatological station includes the

observation of temperature, relative humidity, vapor pressure and

precipitation. The rain gauge stations have a manual rain gauge which is

observed once in 24 hours at 08:45 Nepal time. Biratnagar Airport only has a

continuous rainfall recording device.

187. After analysis of the network and the facilities available presently for flood

forecasting purposes, the following points are observed and recommended:


89

a. The existing network is not designed for flood forecasting purposes.

This network has to be tailored in the light of flood forecasting

requirements. The present network has only 6 functional AWLRs of

which only the Sapta Koshi Chatra station is the most important. Data

from the other 5 stations will contribute very little in the Koshi flood

forecasting task.

b. The same problem exists with rain gauge stations in the basin. Many

rain gauge stations are in the district headquarters and in the Terai

area. Being a mountainous catchment and having very little lead-time,

the network is to be modified and the rain gauge stations are to be

improved by installing automatic rain gauge recorders for real time

data transmission.

c. Data collection, analysis and the transmission system are to be

modernized

d. A Flood Forecasting Centre (FFC) has to be established at Chatra to

facilitate a data hub, an analysis wing and flood forecasting and an

early warning release.

e. Real time data transmission from the river gauges and rain-gauge

stations is to be fully automated using satellite links or other remote

sensing devices so that the FFC could retrieve the data at any time.

f. Himalayan glaciers have become very active resulting in the

formation and expansion of glacial lakes. The UNEP and ICIMOD

study of 2002 shows that 26 glacial lakes of the Nepalese Himalayas

are potentially dangerous and can create Glacial Lake Outburst Flood

(GLOF). GLOF of smaller magnitude during the dry season may not

influence the Koshi plain area much but, if it is combined with the

monsoon rain-fed flood it may cause heavy casualties. Therefore the

FFC is to be strongly linked with the GLOF monitoring system.

g. The FFC at Chatra would disseminate flood information and issue

warnings. It would also be responsible for raising public awareness.


90

h. Additionally, a flood hazard map is to be prepared to identify the risk

area in relation to the flood level. It will help in ascertaining flood

affected areas and information dissemination to the people.

5.2.3 Strategy to prepare a Flood Standing Order

188. Preparation of status reports for appropriate stretches from the Chatra confluence

and identification of the desired level of preparedness associated with each of the

stretch. Ideally, there should at least be an ultra sonic technique-based sensor,

a staff gauge or radar installed to determine flow. The Joint Koshi High Level

Committee could request the Department of Hydrology and Meteorology

and Department of Water Induced Disaster Preparedness to carry out the

feasibility and install such a system.

189. Re-evaluate and re-design of hydrometric system in the basin: There is a need to

reevaluate the sufficiency of the stations that DHM maintains and their

effectiveness in relaying the relevant information to processing hubs. There is

a need to establish more number gauging stations on the stretch from the

confluence at Chatra to the Barrage. Local people may be trained and

instructed to provide the reading or any visual observation by phone to the

authority.

190. Establishing basic protocol for information collection, processing and dissemination:

For this a standard guidebook can be prepared. According to the water level

at Chatra and in the AWLR, established in the 42 KM stretch, the flood and

its intensity may be defined as: Minor Flood Level; Major Flood Level;

Dangerous Flood Level and Critical Flood Level.

191. Flood forecasting: The DHM should collect hydrological and meteorological

data from all river gauging stations and rainfall stations in the basin. The

usual method can be adopted to provide the daily stage heights and rainfall

data to the monitoring centre in Chatra (or in any other of the other station

before the barrage) at the end of each month. However, when floods are

expected during the monsoons, field personnel can be asked to submit the

hourly data to the monitoring centre via telephone and radio transceivers. If a


91

flood of a very high magnitude is expected, field personnel can be instructed

to provide stage heights and rainfall figures hourly. Based on these, runoff

figures can be calculated using rating curves and the MIKE 21 or MIKE

FLOOD package, and the areas that would be inundated can be made known

to the public through radio and television. Simultaneously hourly stage

heights can be plotted and using previous experiences, a rough idea of the

intensity of the flood could be arrived at.

192. Flood warning: When the water level reaches minor flood level at Chatra or

on other established stations with the continuous rainfall in the upper

catchment, a minor flood warning can be given. At this time the flood

monitoring centre can issue warnings to the public via television, radio, the

district office and the police stations, using loudspeakers. This information

can simultaneously be shared with people in India. The level and seriousness

of the warning may be increased as the water level height increases.

193. List of accountability: An office for the flood committee can be instituted at the

Regional DWIDP office in Biratnagar with a mandate to share information

with their Indian counterparts. For mitigation of floods in the Koshi, the

currently established RRU may be used. This may receive instructions on an

‘as and when needed’ basis, or when notification of a flood of major or

dangerous level is received, from the JHLC.

5.3 Assessment of Early Warning System (EWS) and Strategy for creating EWS

194. The Department of Hydrology and Meteorology (DHM), the principal

collector and disseminator of hydro-meteorological data of Nepal, has

established several hydrological and meteorological stations in Koshi River

basin (see section 5.2 for details).

195. The team assessed and categorically states that frequency of discharge

measurement for developing rating curve is very low. Not least to note the

reliability of rating curve is questionable. That means discharge data


92

computed from rating curve and all assessments made thereof are

questionable.

196. The team found that high frequency discharge and rainfall data, e.g. hourly

data are not available. Daily data is collected and is available to purchase it.

Numerical weather forecast for the basin is not available. Similarly no

telemetry system is installed to transmit data in real time.

197. As noted earlier, Koshi Basin receives bulk of its waters from the Chinese

side. There is no hydrometeorological data exchange agreement between

China and Nepal on the basin. This situation is complicated by sparse

raingauge network, no data on rainfall intensity, as well as prevailing poor

understanding of space and time variability of rainfall. Thus, full

hydrological regime can not be represented due to limited number of stream

gauging stations. Similarly, there is no systematic snow measurement except

in two stations. The available length of record is generally short and only a

few variables are being measured.

198. Similarly, continuous records of sediment load data are not available. There

is no high resolution DEM that can be accessed and there are no properly

surveyed cross-sections. Although DHM has a unit named ‘Flood Forecasting

project’, forecasting has not been started yet due to lack of real time data

transmission system, forecasting model and dissemination system. Neither

there are any solid efforts in place that can change the system hitherto in

place anytime soon. There are very few trained hydrologists to produce

reliable forecasts.

199. Given the recurrence, importance and huge implications of the Koshi River

flooding, it is imperative that an early warning system be developed for the

river, spanning over the entire river basin across Nepal and India.

200. The early warning system must use stage data from a Real-Time Data

Acquisition System (RTDAS) with electronic sensors to measure river stages.


93

201. A few, automatic rain gauges must be installed in the catchment area.

Locations for these must be decided based on hydrologic features of the

catchment.

202. Simple and computationally fast flood forecasting models must be developed

specifically with the real time data likely to be available. For example, use of

Artificial Neural Networks (ANNs), that use the rainfall in the catchment

area and river stage at several locations in the river on a real time basis may

be developed to issue flood forecasts.

203. Separate ‘soft’ warnings may also be issued based on the structural

conditions of the embankments and the spurs, even in the absence of a

critically high flood forecast.

204. Administratively, a single window should be created for real-time data

acquisition (both hydro-meteorological and structural), executing the

forecasting models and issuing warnings.

205. Currently improving data collection is the only way forward as it will be key

to establish the EWS and thus better the flood preparedness in the

downstream stretches.

a. There is a need to develop a concept and reach understanding on data

collection protocol between China and India.

b. There is a need to prepare a finer resolution (preferably 5-10 m

resolution) DEM of Koshi River. Most analyses appears to have been

done based on the high resolution freely available DEM (SRTM 90m

DEM). Higher resolution DEM will be needed to get more accurate

drainage network, slope, drainage length and cross-sectional

parameters, and to produce quality inundation map. There is a need

to explore the possibility of generating high resolution DEM from

available contour map.

c. As regards hydro-meteorological data, the responsible agency, DHM,

is desired improve existing hydro-meteorological network density.


94

d. Efforts should be made to automate hydrological and meteorological

data recording and collection system and collection of continuous

data with short intervals. This may be coupled with real-time

communication system to transmit data from field to dedicated

forecast offices.

e. Rather than depending on traditional methods of discharge

measurement, which is quite tedious and less accurate for large rivers,

the possibility of modern methods should be explored. For Example,

the measurement of discharge may be done using ultrasonic system

(acoustic signal) and the measurement of discharge from space may

be enhanced by coupling data collection with satellite-based sensors

that can measure hydraulic variables, such as water-surface width,

water-surface elevation and slope, and the surface velocity of rivers.

Similarly for water level data, measurement of water level may be

initiated using radar sensor (microwaves).

f. Much also is needed to improve the data transfer situation. Although

communication system has really taken a leap forward in the recent

years, existing system still rely on wireless system. Use of internet,

CDMA, satellite or other wireless communication system can really

enhance the data dissemination.

g. Recently, there have been many breakthroughs on the application of

satellite-based rainfall for ungauged or poorly gauged basin and the

same technology may be introduced to develop near real time flood

forecasting system until a more ground-truthing based approach is

established in Koshi. A quick assessment to determine the feasibility

of using satellite-based rainfall data is therefore very timely.

h. There is a need to establish a basin-wide hydro-meteorological

database and management system or at least develop a barebone

structure that can be collectively worked on by the countries that

share the basin or are prone to flooding.


95

206. The team also suggests that there is a need to simultaneously improve the

flood forecasting modeling capability on the part of the authorities. These

may be process-based hydrological and hydraulic models (routing models);

hydrodynamic model, or soft-computing models.

207. The team suggests application of BTOPMC (Block wise use of Top model

with Muskingum-Cunge routing), which is distributed hydrological model

developed at the University of Yamanashi, Japan. Given the model is based

on freely available DEM and data on soil, land use, and NDVI and CRU

climate data (for computing evapotranspiration). The model offers grid by

grid computation of flow and also spatial distribution of variables. It is noted

however that the model has several calibration difficulties and may take a

very high computation time for large basins.

208. Similarly, there may be a staged approach for which universities or research

institutions may be contracted. Utilization of lumped conceptual

hydrological models like NAM, TANK, UBC, HBV etc. by dividing up the

basin into a number of small sub-basins. This will be easy to implement and

also be rapidly computation time. However, this can also render difficulties

in calibration and may not provide reliable result outside the range of

calibration.

5.4 Maintenance of Spurs

209. The existing spurs along the river bank are long and spaced at considerable

distances. As the spacing of spurs is a function of the spur length, the existing

arrangement of long spurs at large distances is theoretically correct. Longer

spurs also keep the river flow substantially away from the embankments.

However, the drawback of this arrangement is that damage to any one of the

spurs washes out the still water pool and erodes the bank line over the entire

distance between that particular spur and the next downstream spur. Thus,

the river flow is allowed approach the embankment over a considerably long

stretch, resulting in the possibility of toe cutting of embankments and


96

possible their breaching. This effect is particularly severe immediately

upstream of the next downstream spur. This phenomenon also stresses the

downstream spur and can result in a chain reaction whereby

210. In view of the above, it is prudent to build a series of shorter spurs at regular

intervals. Though it draws the river flow closer to the bank line, this

arrangement minimizes the exposed length of the embankment in case of

failure of any one particular spur in the series of spurs. Even in this case, all

the problems referred to above may still come into play within the affected

span; however, the affected span is localized and is, therefore, not likely to

affect most of the downstream spurs. The localization of the problem also

eases repair and rehabilitation works. Needless to say, the repair and

maintenance of shorter spurs is also easier than that for longer spurs.

211. During the inspection, it was noticed that protection at the spur noses were

damaged or completely washed away. As they are most vulnerable to

damage during floods, the spur noses should be provided with adequate

protection through boulder pitching or placement of gabions or

interconnected pre-cast concrete blocks.

212. It appears that the spurs and embankments have not been regularly

maintained over the past few years. Therefore, regular inspection and

maintenance of the spurs and embankments, particularly before the onset of

monsoon, must be made mandatory.

5.5 Comprehensive study to redesign the spurs

213. While it is necessary to treat the Koshi river flooding with an integrated

approach, addressing river morphology, hydrology, engineering and socio-

economic aspects simultaneously, the designs of the structural measures

already in place, (viz., the embankments, the barrage and the spurs) must be

revisited and checked for their adequacy in view of the complexities of the

problem and the huge implications of structural failures.


97

214. The spurs were designed as part of the Koshi project in the late fifties/early

sixties. The locations, the length and the structural aspects of the nose and the

apron of the spurs should be studied with sophisticated mathematical

models using the latest methodologies that consider the hydrodynamics and

geomorphology of the river. The end results of such studies should be aimed

at providing renewed designs of the spurs – in terms of their location,

geometry and structural design.

215. The option of providing a larger number of correctly located spurs which are

shorter i.e. smaller in size, both on the east and west banks, must be explored

in these studies. The shorter spurs may be easier to maintain and are likely to

be less prone to puncturing.

5.6 Dam break analysis

216. Comprehensive dam break analysis with good quality data from both the

Nepal and Indian sides, should be carried out. The aim of such analysis

should be to assess implications of flooding if a breach occurred again. The

analysis should be carried out with different flood discharges and resulting

vulnerability maps must be put in place. Typical data required for such an

analysis are the flood hydrographs, the channel geometry and hydraulic

characteristics, complete mapping of the floodplains, including contour

maps, land use patterns and socio-economic data on the settlements in the

floodplains. Sophisticated models are now available for carrying out such

analyses and must be made use of.

217. The dam break analyses should be carried out with simulated breaches at

several potential locations on the embankment and also at locations where

river diversion works are in place (e.g., around chainage 23.1 km to 26.9 and

at Pulthedunga


98

5.7 Generating ‘what-if scenarios’

218. With the dam break analysis and/or otherwise, a number of critical flooding

scenarios should be worked out for the river.

219. A well calibrated hydrodynamic model that also considers sediment

deposition and river morphology (e.g., the MIKE21 or the HEC-RAS) may be

used along with a specialist dam break model to generate the scenarios. The

services of academic and research institutes well versed with such modeling

must be used for generating the scenarios.

220. A typical non-exhaustive list of the possible scenarios to be generated is:

a. Similar embankment breach occurring in immediate future, with

varying discharges;

b. Higher floods and larger breaches; number of breaches occurring

simultaneously at several locations.

c. Overtopping floods – the embankment does not breach but gets

overtopped, both on eastern and western banks.

d. Flooding on the western side – embankment breach on the western

slide Deposition of heavy sediments due to GLOF

e. Simultaneous embankment failure on eastern and western banks

f. Lake formation due to landslides

g. Cloud burst events, resulting in instantaneous high discharges.

5.8 Monitoring mechanism

221. A strict monitoring mechanism must be put in place immediately to help in

issuing early warnings.

222. As an important component of monitoring, extensive instrumentation must

be put in place to detect scouring at the spurs and at potential locations along

the two embankments.


99

223. A real-time data acquisition system (RTDAS) may be implemented to

monitor a critical rise in water levels at several locations in the river. Such

systems typically involve electronic sensors and will be useful in issuing

early warnings.

224. Routine general monitoring and periodic maintenance of spurs and

embankments must be put in place.

225. Additionally, comprehensive stretch-wise monitoring that includes

examining the structural condition of the embankment and the spurs must be

taken up periodically.

5.9 Manpower Training:

226. Trained professional manpower is required for flood fighting. Personnel

working in EWS need extensive in-house and a practical training (which may

be in India for a period of about a month during the flood season) where

there is a functional EWS followed with refresher courses. Local people are to

be trained in flood fighting and attend periodic awareness-raising program.

5.10 Construction of Retired Embankment

227. The authorities should hasten the existing repair work and also consider

constructing additional works, remembering that in spite of proper

maintenance, the possibility of a breach in the eastern embankment during

high floods in future years, cannot be ignored. An appropriate measure for

this purpose appears to be to provide a retired embankment. The location,

profile and alignment of the proposed retired embankment shall have to be

decided based on detailed hydraulic and hydrological investigations. The

third phase would consist of long term planning and would be considering

the continued aggradations within embankments rendering the further

raising of the embankments, even after long period.


100

228. The provision of an additional retired flood embankment is considered as an

appropriate provision so that if the existing embankment is breached again,

the retired embankment would come into play and provide protection

against flooding. This retired embankment can better be compartmentalized

by providing cross embankments at intervals so that if and when a breach

occurs in the existing embankment, flood water would fill the specific

compartment opposite the breach and form a pond. The result of this will

stop further development of the breach and closing the breach will become

easier, faster and much less expensive.

229. Such a retired embankment will obviously involve high cost but it will be

justified considering the colossal damage and cost incurred in flood fighting

and flood relief work entailed last year after the breach in the existing

embankment. Details investigations of the feasibility of this proposal should

be commenced at the earliest opportunity. This shall require detailed

hydraulic and hydrological investigations, involving both mathematical and

physical modeling, which can be commenced immediately.

5.11 Long term issues – climate change

230. Climate change is likely to have an adverse impact on the intensity,

magnitude and frequency of floods, particularly in the snow fed Himalayan

Rivers. A systematic study should be taken up to work out the intensity-

duration-frequency (IDF) relationship for the Koshi river basin in the face of

climate change. These relationships must be used to check the adequacy of

the structural designs and to formulate the non-structural responses (such as

issuing early warnings).


101

5.12 Recommended activities and responsibilities

Sl. No.

Activity Primary Responsibility

Secondary responsibility

Timeframe

Comments

1. Disseminate the Rapid RHA Report

UNCT - Immediately Dissemination of RHRA

2. Second stage HRA with detailed field investigation

MOHA/DWIDP/MPPW

OCHA , ADB, UNESCO, IASC

Immediately

3. To ensure implementation of HRA recommendations

MOWR/MPPW/Relevant Line Ministries and Department

ADB/UNDP/IASC 1-3 years

4. Technical examination, rehabilitation, maintenance and monitoring of Spurs and

Embankments

MOWR/WECS (through bilateral channels)

DWIDP/ District Authorities

Continuous Until a permanent solution is

reached 5. Establishment and operation

of a Koshi Basin Flood

Forecasting System

DHM/DWIDP ADB, Bilateral agencies 2-5 years Regular

6. Establishment and operation

of a Community-Based Early Warning System

DDRC /DDC UNDP. IASC 1-3 years 6 months for

establishment of CBDP Unit

7. Awareness creation and

capacity enhancement of local people and CBDP unit

DDC/UNDP UNCT 1-2 years

8. Formulation of a flood-disaster

response plan fro Koshi

DDRC/DWIDP/MO

WR/UNDP

NRCS/IASC 6 months

9. Redeliniation of Koshi Wildlife

Reserve

Ministry of forest,

department of wildlife

- 6 months – 1

Year

10. Address possible labor issues Ministry of labor, district administration , representatives of political parties

DDC/CDO/ILO/UNDP/ADB

Before the onset of monsoon

11. Installation of river monitoring devices in the stretch below Chatra

DHM, DWIDP Donor agencies/UNCT 1-2 years

12. Establishment of embankment monitoring committees

District administration , representatives of political parties,

liaison office

MOWR (through bilateral negotiations)

Before the onset of next monsoon

13. Preparation of detailed standing order for Flood

Preparedness

DWDIP/UNCT MPPW 1-2 years

14. Preparation of implementation strategy for risk management

plan

DDRC/ DWIDP/NDP

MPPW/MOHA/UNCT/ ADB and other

bilateral donor agencies

1 year

15. Undertake detailed modeled- based geomorphology and river engineering study

MOWR (through bilateral negotiation)

UNCT 1-5 years Scientific Investigation for Disaster Reduction

16. Rehabilitation of degraded/damaged land

DAO/DDC?FAO UNDP/MOLD/ ADB/UNCT

1-4 year


102

Sl. No.

Activity Primary Responsibility

Secondary responsibility

Timeframe

Comments

17. Resettlement of displaced families

MoHPP, MoLRLM/MoHA/MOLD/MOAC

UNDP/UN HABITAT/ UNICEF/UNCT/ADB

0-2 year

18. Improvement of alternative access roads , with emergency management corridors

DoR/DDC/DDRC ADB/UNDP/WB/WFP (under food for work)

1-5 years

19. Skill development and alternative livelihood for displaced people

CTEVT/DAO/DoSCI UNCT, ADB/WB/ADBN

3 years

20. Flood disaster preparedness – shelter place development and

management, development of food security system

MOHA/DDRC/NPC/DDC

UN habitat, UNDP, FAO, IOM, WFP,

NRCS/UNICEF

3 years

21. Flood disaster risk

communication- preparation of posters, pamphlets, audio visual broadcast

MoIC,

DDRC/NPC/DDC/DEO

UNCT, IASC/UNDP 1-3 years

22. Institutional capacity building: central and local bodies including NGOs/INGOs through training

MOHA/DDRC/DDC/UNDP

UNCT/IASC 1 year

5.13 Medium term Plan

231. There is an urgent need to implement the medium term action, which has

already been agreed and some funds secured. The RHRA team proposes that

it will be most appropriate in the medium term to consolidate the findings of

the rapid assessment, develop at least two detailed dam-break analysis, and

develop a detailed standing order for flood risk reduction in the confluence

below Chatra.

232. The risks do exist but there are enough tools available which can be used to

minimize them to make them acceptable risks. Still more research and, most

importantly, willingness to work together is needed.


103

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Documents

rapid hazard and risk assessment post-flood return analysis