Draft Inception Report - Disaster risk reduction · Draft Inception Report Progressive Realisation of the IncoMaputo Agreement (PRIMA) Study for the Implementation of the Permanent

Draft Inception Report

Progressive Realisation of the IncoMaputo Agreement (PRIMA)

Study for the Implementation of the Permanent Solution in the Lower Usuthu Breach

SALOMON LDA.

Supported by: BEUSTER, CLARK & ASSOCIATES, TÉCNICA and UEM

Rua Comandante João Belo 189

Tel: +258 21315161

e-mail: [email protected]

Maputo, Moçambique

May 2010

Usuthu Breach Inception Report

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REPUBLIC OF MOÇAMBIQUE MINISTRY OF PUBLIC WORKS AND HOUSING

Direcção Nacional De Águas

CONSULTING SERVICES FOR THE STUDY FOR THE IMPLEMENTATION OF THE PERMANENT SOLUTION IN THE LOWER USUTHU BREACH

INCEPTION REPORT Prepared by: Salomon, Lda Prepared for: Tripartite Technical Committee (TPTC) between Moçambique, South Africa and Swaziland

May 2010 Draft V0.1


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Contents

1 INTRODUCTION AND BRIEF DESCRIPTION OF THE PROJECT .......................................................................... 1

2 OBJECTIVES AND SCOPE OF THE PROJECT ....................................................................................................... 4

3 SCOPE OF WORK ............................................................................................................................................... 5

4 INFORMATION COLLECTION AND ASSESSMENT ............................................................................................. 6

4.1 PREVIOUS STUDIES ........................................................................................................................................ 6 4.1.1 Introduction.......................................................................................................................................... 6 4.1.2 Scoping Report ..................................................................................................................................... 6 4.1.3 Design Report ....................................................................................................................................... 7

4.2 HYDROLOGY AND HYDRODYNAMIC MODELLING .................................................................................................. 7 4.3 GEOMORPHOLOGY ........................................................................................................................................ 8

4.3.1 Introduction.......................................................................................................................................... 8 4.3.2 Overview of the geomorphology of the river site ................................................................................ 8 4.3.3 Stream Stability .................................................................................................................................. 10 4.3.4 River Rehabilitation ............................................................................................................................ 11

4.4 ECOLOGICAL AND ENVIRONMENTAL INFORMATION ............................................................................................ 11 4.5 SOCIO-ECONOMIC INFORMATION ................................................................................................................... 11

4.5.1 Methodology ...................................................................................................................................... 12 4.5.2 Cost analysis of alternative solutions................................................................................................. 13

4.6 LAND AND TOPOGRAPHIC INFORMATION .......................................................................................................... 13 4.6.1 Topographic information ................................................................................................................... 13 4.6.2 Aerial Photography ............................................................................................................................ 13 4.6.3 Satellite Imagery ................................................................................................................................ 14

4.7 OTHER INFORMATION RELEVANT TO THE STUDY................................................................................................. 14

5 FLOOD HYDROLOGY AND HYDRAULICS ......................................................................................................... 15

5.1 SCOPE AND OBJECTIVES ................................................................................................................................ 15 5.2 FLOOD HYDROLOGY ..................................................................................................................................... 15

5.2.1 Scope and Objectives ......................................................................................................................... 15 5.2.2 Previous Studies ................................................................................................................................. 15 5.2.3 Methodology ...................................................................................................................................... 16

5.3 HYDRODYNAMIC MODELLING ........................................................................................................................ 17 5.3.1 Introduction........................................................................................................................................ 17 5.3.2 LIDAR survey of the lower Usuthu...................................................................................................... 17 5.3.3 Configuration of the preliminary hydrodynamic model..................................................................... 17 5.3.4 Potential for the formation of alternative upstream breach sites as a result of the implementation

of a permanent solution .................................................................................................................................. 19 5.3.5 Proposed additional runs for detailed simulation.............................................................................. 20

5.4 HYDRAULIC DESIGN ..................................................................................................................................... 21 5.4.1 Preparatory work required for the preliminary design ...................................................................... 21 5.4.2 Preliminary design.............................................................................................................................. 21

6 SOCIO-ECONOMICS ........................................................................................................................................ 22

6.1 BACKGROUND............................................................................................................................................. 22 6.2 MATUTUINE DISTRICT AND CATUANE ADMINISTRATIVE POST .............................................................................. 23

6.2.1 Overview ............................................................................................................................................ 23 6.2.2 Economic activities ............................................................................................................................. 23 6.2.3 Agriculture in Catuane AP – the predominance of the family sector................................................. 24 6.2.4 Fisheries.............................................................................................................................................. 26 6.2.5 Other social activities related with the river water flows .................................................................. 27

6.3 ISSUES TO INVESTIGATE AND METHODOLOGIES AND TOOLS TO BE USED .................................................................. 27


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7 PRELIMINARY THOUGHTS ON THE REASONS FOR AND CONSEQUENCES OF THE BREACH ........................ 29

7.1 CAUSE OF THE BREACH ................................................................................................................................. 29 7.1.1 Introduction........................................................................................................................................ 29 7.1.2 Timing of the breach .......................................................................................................................... 29

7.2 FAILURE OF THE EMERGENCY REHABILITATION WORKS ....................................................................................... 31

8 POTENTIAL REHABILITATION OPTIONS ......................................................................................................... 32

8.1 SELECTION OF REHABILITATION OPTIONS ......................................................................................................... 32 8.2 DETAILS OF POTENTIAL REHABILITATION USING LOCALLY BORROWED MATERIAL (OPTION (C)(I)) ................................. 32

9 PROPOSED APPROACH AND DELIVERABLES.................................................................................................. 35

9.1 PHASE I ACTIVITIES: PRELIMINARY DESIGN ........................................................................................................ 35 9.1.1 Step 1 (a) : initial discussions for problem definition ......................................................................... 35 9.1.2 Step 1 (b) : preliminary site investigations, and 1(c) : investigation of failed temporary solution .... 35 9.1.3 Step 1 (d) : understanding the socio-economic and environmental consequences of the breach .... 35

9.2 PHASE 2 : DESIGN OF INTERVENTION MEASURES ............................................................................................... 36 9.2.1 Step 2(a) : Flood Hydrology ................................................................................................................ 36 9.2.2 Step 2(b) Hydraulic analysis ............................................................................................................... 36 9.2.3 Step 2(c): Hydraulic Design ............................................................................................................... 37

9.3 STEP 3: FLOODPLAIN MANAGEMENT.............................................................................................................. 37 9.4 STEP 4: MANAGEMENT OF REINSTATED FLOW CONDITIONS ............................................................................... 37

10 PROPOSED WORKPLAN .................................................................................................................................. 38

11 PROJECT MANAGEMENT ................................................................................................................................ 39

11.1 INTRODUCTION ........................................................................................................................................... 39 11.2 COMMUNICATION ....................................................................................................................................... 39 11.3 REPORTING ................................................................................................................................................ 40

12 REFERENCES .................................................................................................................................................... 41

APPENDIX A: CONCEPT DESIGN – OPTION (c)(i)


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List of Figures Figure 1-1 : Location of the Usuthu/Maputo Breach ................................................................................................. 1 Figure 1-2 : Close-up of the Breach Site (Source: DWAF, 2007) ................................................................................. 2 Figure 1-3 Aspect of the sandbag berm solution during final construction phase .................................................... 2 Figure 1-4 : Failed Emergency Rehabilitation (Source: Current Project, 2010).......................................................... 3 Figure 4-1 Older aerial photographs showing the geomorphological settings of the river before the breaching the

channel ....................................................................................................................................................................... 9 Figure 4-2 Recent aerial photographs showing the new channel of Maputo River ................................................ 10 Figure 5-1 : Ground levels obtained from LIDAR survey .......................................................................................... 17 Figure 5-2 : Boundary of Preliminary Usuthu model................................................................................................ 18 Figure 5-3 : Simulated water depth at a steady discharge of 100m

3/s ................................................................... 19

Figure 5-4 : Potential upstream breach at 350 m3/s discharge and implementation of permanent rehabilitation of

current breach site ................................................................................................................................................... 20 Figure 7-1 : Water Levels at E7 Catuane .................................................................................................................. 29 Figure 7-2 : Double mass-plot of average monthly water levels ............................................................................. 30 Figure 7-3 : Near infrared composite - 2010/02/25................................................................................................. 31

List of Tables Table 4-1 : Flood Hydrology and Hydrodynamic Modelling Information .................................................................. 8 Table 4-2 : Aerial Photography ................................................................................................................................ 14 Table 4-3 : Landsat imagery..................................................................................................................................... 14 Table 5-1 : Hydrology and Hydraulics Sub-Tasks ..................................................................................................... 15 Table 5-2 : Flood peak data obtained from the LUSIP study.................................................................................... 16 Table 6-1 : Maputo/Usuthu River Breach - Preliminary List of Contacts ................................................................. 28


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List of Abbreviations

DNA

DWAF

National Directorate of Water (Republic of Moçambique)

Department of Water Affairs and Forestry (South Africa). Now the Department of

Water and Environmental Affairs

GOS Government of Swaziland

JMRBWRS Joint Maputo River Basin Water Resources Study

LUSIP Lower Usuthu Small-holder Irrigation Project

MNRE Ministry of Natural Resources and Energy (Swaziland)

PRIMA

TPTC

Progressive Realisation of the IncoMaputo Agreement

Tripartite Permanent Technical Committee

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1 INTRODUCTION AND BRIEF DESCRIPTION OF THE PROJECT

The current project is part of the initiatives under the Progressive Implementation of the IncoMaputo

Agreement between Mozambique, Swaziland and South Africa.

In August of 2005 the Government of Mozambique reported to the Government of South Africa, a

drastic reduction of river flow along the river stretch in the Catuane area, which is aggravated during

dry seasons, impacting on human water supply, livestock watering, fishing, ecosystems and irrigation,

among other negative impacts. The reduction in river flows was caused by a breach that formed in

the southern bank of the Usuthu, diverting the river via Banzi Pan to the Phongolo River. The breach

is located approximately 16 km downstream of the point where the river exits Swaziland, and about

11 km upstream of the confluence of the Usuthu and Phongolo Rivers (Figure 1-1 and Figure 1-2).

The Governments of Mozambique and South Africa have agreed that the situation prior to the

diversion should be restored, i.e. the diversion should be rehabilitated and the river contained in the

original water course. The South African Minister of Water Affairs and Forestry (DWAF, now the

Department of Water and Environmental Affairs) approved emergency remedial work on

15 November 2005. According to DWAF the decision could not be implemented immediately because

of the good rains early in 2006, which lead to higher flows in the river, alleviating the problem and

making it unpractical to repair the breach under the high flow conditions (DWAF, 2007). To prepare

for rehabilitation when river flows are low enough, the DWAF Directorate Civil Engineering initiated a

geomorphological study and an aerial survey to study the problem in more detail (Letter signed by

Deputy Director-General: Regions on 6 June 2007).

Figure 1-1 : Location of the Usuthu/Maputo Breach


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Figure 1-2 : Close-up of the Breach Site (Source: DWAF, 2007)

At the Tripartite Permanent Technical Committee (TPTC) meeting on 22 May 2007 Mozambique

reported that the Usutu River has again stopped flowing. The South African delegation to the TPTC,

lead by DDG: Regions, undertook to construct the rehabilitation work proposed in 2005 before the

start of the next wet season. A joint task team between Mozambique and South Africa was

established to implement this decision. Emergency rehabilitation works in the form of a sandbag

berm were constructed and completed in October 2007 (Figure 1-3).

Figure 1-3 Aspect of the sandbag berm solution during final construction phase


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The berm was constructed in a form of overflow weir but strong enough to allow an overflow of

roughly 1300 m3/s (estimated at the time to correspond to a 1 in 2 years flood). However, during the

subsequent wet season the berm was washed away, for reasons that must still be determined (Figure

1-4).

Figure 1-4 : Failed Emergency Rehabilitation (Source: Current Project, 2010)


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2 OBJECTIVES AND SCOPE OF THE PROJECT

The current study was commissioned under the tripartite initiatives between Mozambique, South

Africa and Swaziland for the Progressive Realisation of the IncoMaputo Agreement (PRIMA) on behalf

of the Tripartite Permanent Technical Committee with the aim to conduct detailed investigations into

(a) the causes for the changes in the river regime, (b) reasons for the failed emergency rehabilitation

measures, and (c) to propose adequate measures for a permanent solution.

The main objectives of the study are thus to provide a comprehensive assessment of what measures

are required to restore the flow path of the Usuthu River to its original course forming the border

between the Republics of Mozambique and South Africa and to prepare a preliminary design for a

permanent solution. The study should look at Technical, Social, Economic and Environmental issues.

The technical investigations should include hydrologic, hydraulic and sedimentation assessments of

the breached area and surroundings to inform a design for a permanent solution.


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3 SCOPE OF WORK The governments of Mozambique and South Africa have agreed to implement a permanent solution

that will restore the river to its most recently known main stem. The objective is to maintain the

existing natural border that has existed for at least 100 years. The consultants approach was

presented in detail in the proposal. This work will be carried out in two stages:

Phase 1: concerning the detailed analysis of the nature of the diversion, possible triggers, and impacts

to the socio economy and environment of the region. To achieve these results the consultancy will

include:

• Review the existing information about the site including existing studies on the Maputo

River as well as those specific to the Lower Usuthu River and the Banzi Pan.

• Conduct an appropriate hydrological assessment of Lower Usuthu section of the River, with

special emphasis on the flood regime (the frequency and volume). The Consultant should

also assess the response of alluvial streams to floods, compiling the existing knowledge of

history of the river response to floods.

• Undertake a geomorphologic assessment of the Lower Usuthu area including the associated

vegetation and present an associated map on erodibility. This analysis should also be

extended regionally to understand the dynamics of the area regarding formation of

streams.

• Conduct a comprehensive hydraulic assessment of the river with due attention to bed and

channel configuration, flow pattern of the river and sediment transport. This will be

supported by detailed topographical surveys.

• Assess the impact of the river deviation on the environment.

• Assess also the socio-economic impacts associated with the deviation of the river.

• Describe possible implications on the deviation of the river on the international border in

light of the international law.

• Based on the hydrologic, hydraulic and geomorphologic assessment, prepare and present a

report giving account of the relevant facts to understand the origin of the deviation.

• Prepare and present optional interventions, especially present ideas on the possible

approach to close the breach. These options will be the basis for a decision by the TPTC on

the options to be considered in the second phase of design.

Phase 2: This phase concentrates on preparing the designs of the rehabilitation works approved by

the TPTC.

• Prepare and present a design report for the rehabilitation of the site, reinstating the river to

its original course.

• Undertake a cost estimate for the rehabilitation works.

• Prepare the bidding documents for the rehabilitation works in Phase 2.

• Assist the client during the bidding process for implementation of corrective measures.


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4 INFORMATION COLLECTION AND ASSESSMENT

4.1 Previous Studies

4.1.1 Introduction

The DNA in Maputo provided background information related to the breach. Most of the reports are

those prepared jointly by Mozambican and South African officials and describe the steps followed by

the TPTC to correct the problem. Other reports refer to briefings by Mozambican officials charged

with monitoring of the solution of the problem and describe the steps taken by the Government of

Mozambique in regard to the issue, particularly the details about the TPTC meetings where the

subject was discussed and the monitoring of the agreed measures that was undertaken.

The technical studies and designs of solution were carried out mainly by South Africa with

participation of Mozambique. The South African Department of Water and Environmental Affairs

provided the following reports that were prepared prior to the emergency rehabilitation work of

2007:

• A scoping report (Wadeson, 2006)

• A design report (DWAF, 2007) which provided the basis for the construction of the sandbag

berm emergency rehabilitation.

4.1.2 Scoping Report

In preparation for the emergency rehabilitation work of 2007, a scoping study was undertaken into

the cause and extent of the problem, and information requirements to carry out a full feasibility for

assessing possible solutions. The report covered the following topics:

• A regional biophysical description placing the area within the (South African) national context

• A local overview and biophysical description

• A geomorphological audit of the study site

• River rehabilitation issues

Key findings of the study can be summarised as follows:

(a) The authors describe the Usuthu River as a naturally unstable river that has accelerated

instability as a result of conditions in the upstream catchment. They cite the numerous

paleo-channels visible on aerial photographs as evidence of frequent channel migration.

(b) “..... environmental and social issues that need to be considered include:

• The loss of an international border

• Fragmentation of an important nature reserve

• Possible loss of protected species to poaching

• The partial loss, and or damage, to an internationally recognised Ramsar wetland site

• Loss of water for downstream users

• Loss of a food source to downstream users

• The potential loss of numerous rare and endangered fauna

• The loss of fish breeding stock for the Usuthu and Pongola River system”

(c) The report recommends the re-establishment of the present channel by reversing the current

situation and using the new channel as a high flow “relief channel” or “by pass channel” by


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construction of a weir that allows overtopping by large floods into the relief channel.

Overtopping on an annual basis is proposed.

(d) Stabilisation of the outlet channel from Banzi pan is recommended. This is to enable the

through flow of flood waters without the formation of a headcut or nickpoint which would

prevent draining of the pan.

(e) The authors are of the view that the creation of a multi stage channel is likely to be “less

successful, more costly, and likely to cause considerable environmental damage”.

4.1.3 Design Report

The DWAF Design Report describes the design of emergency rehabilitation works to allow time to

consider long-term measures assessed by a future planning study. The proposed temporary measure

was to block the diversion into the new channel with sandbags filled with sediment obtained from the

main river bed. The report lists the following reasons for the use of sandbags as a temporary

measure:

“...

• There is an abundance of sand and only sand available in the area. Sand alone cannot be used

to block the breach because it erodes from wind and wave action. Sandbags however would

not be eroded as effortlessly as sand.

• Because the Ndumu Game Reserve is a proclaimed protected area it is not possible to use

heavy vehicles and equipment to carry out the work. Manual labour therefore has to be used

to construct the diversion structure. Sand bags can be carried filled and stacked by hand.

• Because the measures are implemented as an emergency it is required to be removed after

two years. The bags must therefore be easily removable also using hand labour.

• The sandbag structure is required to break during floods to protect the river bank from failing

at another location. Sandbags allow the structure to break in a controlled fashion.”

Based on a series of four laboratory model tests, a 1.6m high weir was proposed. The weir would

allow water to spill over the structure to a maximum depth of 600mm (80m3/s), at which point the

structure was designed to fail to protect the river bank and to prevent a breach occurring elsewhere.

The design report of the emergency rehabilitation works has particular relevance to the current study

(refer to Section Error! Reference source not found.).

4.2 Hydrology and Hydrodynamic Modelling

The status of data and information collection on basin and flood hydrology and hydrodynamic

modelling is as follows:


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Table 4-1 : Flood Hydrology and Hydrodynamic Modelling Information

Item Source Status Comment

Reports

Siphofaneni and Mhlatuzane

Bridges Design Flood Analysis

Aurecon /

MNRE

Collected Permission to use the data

and model configurations to

be obtained from MNRE

LUSIP Design Flood Analysis SWADE Collected

JMRBWRS Hydrology PRIMA / GOS Collected

Flow and water level data

E7 – Catuane ARA-Sul Partially collected Water level recordings have

been collected. Rating

tables must still be obtained.

Gauge-plate zero surveys to

be done during main project

phase.

E393 – Fronteira Oest ARA-Sul Partially collected

Relevant Swaziland Flow

Records in the Usuthu Basin

MNRE Collected Sourced from JMRBWRS

Relevant RSA Flow Records in

the Usuthu and Phongola

Basins

DWAF Outstanding Download from DWAF

website

4.3 Geomorphology

4.3.1 Introduction

During the design of temporary measures for the rehabilitation of the breach, the South African

Government commissioned a study to determine the reasons for the breach. The consultant

undertook a complementary assessment of the geomorphology of the area and the results are

presented in Section 4.3.2. The scoping report for the emergency rehabilitation (DWAF, 2007)

contains a geomorphological audit that provides a qualitative assessment of stream stability and

general environmental health, and identifies areas for remedial measures. The main findings of the

audit are summarised in the subsequent sections. [Where appropriate, comments and

interpretations from the current study are inserted in italics.]

4.3.2 Overview of the geomorphology of the river site

The Usuthu River exits Swaziland through the Libombos volcanic formations and then flows through

sedimentary formations before draining into the Maputo Bay. Around the breach site, one of the

river sections shows a meandering behaviour and susceptibility for relative rapid change. Channels

can change continuously their position due to the natural and human processes.

The constant natural changes verified along meandering rivers take place as part of the natural

behaviour of streams that are in constant search of equilibrium of the system. In the case of the study

site, based on the aerial photographs from different time periods, it is clear that the main channel of

the Maputo River has changed over time. Figure 4-1 Older aerial photographs showing the

geomorphological settings of the river before the breaching the channel shows a mosaic of aerial

photographs from the study area showing geomorphologic details of the river.


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Figure 4-1 Older aerial photographs showing the geomorphological settings of the river before the breaching

the channel

Two types of changes can be verified on meandering river systems. One of the changes is the lateral

migration that occurs regularly causing features of lateral accretions. During this process, sedimentary

faces are deposited and they provide a record of the migration process. Another type of change

concerns overbanking processes where the main channel of the river overtops, usually creating a

crevasse splay delta shape, a cut bank or even the abandonment of the main channel, depending on

the physiographic characteristics of the area. In the aerial photographs shown in Figure 4-1, part of

the paleo-channel is shown by arrows. The arrows also show the pattern of sediment flow along the

study area during extreme events of flooding. In the same figure “A” shows the lower part of the

floodplain that has been episodically affected by floods. In this area, alluvial sediments are normally

deposited. Besides the lower part assigned by “A”, internal dunes assigned by “B” occur occupying

upper parts. The internal dunes divide the floodplain in two parts as shown in a circle marked by

question mark. Thus, the lower part of the floodplain below the breach site shows a cycle of sediment

circulation indicated by arrows. This suggests that this area has been a part of floodplain isolated

from the other (left) side by internal dunes. It probably means that the paleo-channel shown by

arrows on the left, has been merely for feeding the leftmost floodplain area.

In recent images (color aerial photographs and LIDAR image, Figure 4-2), it can be seen that the new

river channel breached through two small elevated bodies of internal dunes (circled feature). This

situation can be caused by a flooding event that has sufficient energy to breach these dunes. The new

channel crosses/cut the internal dune marked by A. This site is crucial for the water flow and

development of the channel. By investigating it further it is possible to establish whether this channel

developing between the dunes is natural or results from some form of man-made changes. To verify

such events would require an extensive field investigation to recover specimens that could indicate

the timing and sequences of events leading to formation of the channels and the adjacent dunes.


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Figure 4-2 Recent aerial photographs showing the new channel of Maputo River

4.3.3 Stream Stability

The geomorphological audit that was referred to at beginning of this chapter gives a summary of

findings related to the nature of the study area:

a) The audit shows that the area downstream of the breach site is largely stable and is held in

position by a well vegetated south bank.

b) The upstream area where the breach has occurred is not within the same dense riparian zone

as that found downstream. It is surmised that this section has still not fully recovered from

the damage caused by cyclone Domoina, 23 years ago.

c) Based on previous research, the audit states that a meta-stable system is characterised by bank-full

height discharges of 1 in 3 year recurrence intervals. Lower values of bank-full discharge would

indicate that the present channel does not have the capacity to carry the floods that occur every 1

to 3 years – the flow which causes most of the long-term sediment discharge. [In the breach

section, a smaller bank-full discharge is probably due to aggradation.]

d) The present-day channel of the Usuthu should be adjusted to a suite of discharges, one of them

being the “re-set” event, a flood with an average return period of between 20 and 50 years. The

“re-set” events are important for mobilising the entire bed of a river, thereby maintaining channel

geometry.

e) The Usuthu River is an alluvial system dominated by sand in the size range 0.06 to 0.5mm. To

entrain and transport this material, a critical velocity of between 0.2m.s-1 and 0.3m.s-1 is

required. Once in suspension the sand will continue to be transported at velocities as low as

0.01m.s-1 to 0.1m.s-1. An observation is made that a flow of only 16m3.s-1 would appear to be

adequate to keep some sand moving through the higher velocity areas of the Usuthu River. [If

a river training option is selected as a permanent solution, discharges equating to these

critical velocities will have to be determined by means of hydrodynamic modelling.]


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4.3.4 River Rehabilitation

a) The audit notes that the breaching of the Usuthu River can be partly attributed to high

sediment yields and reduced discharge and that a passive solution is to remove the problem

source in the catchment and wait for the river to re-habilitate itself. It further notes that the

consequent natural morphological and biological recovery may be a very slow process (10 –

100 years).

b) The audit recommends a relief or bypass channel as the logical choice for an active

rehabilitation solution in the Usuthu River. Such a channel diverts excess water from the

main channel during periods of high flow, and reduces the likelihood of flooding and erosion.

Two main types of relief channels are identified:

i. Channels with permanent water flow. These have greater value as aquatic habitat.

ii. Channels which are predominantly dry except during periods of high flow. These are

less beneficial to biota but may be less prone to erosion than relief channels with

permanent flow.

c) It is noted that the overall benefit of relief channels is that they provide an environmentally

friendly and viable alternative to channel widening.

d) According to the audit, river training by means of sandbags, levees and dikes is the least

preferred option.

i. The sensitive nature of this site in the Ndumo Nature Reserve, and the fact that the

river has already cut its own relief channel are cited as the reasons for not preferring

this type of option.

ii. Manmade levees have disadvantages because they disrupt the natural functioning of

the floodplain in directing waters into the main channel, and in large floods when the

levees are overtopped, they can prolong the flooding duration. If they are built too

close to the river they can also result in the loss of wetland areas. The use of smaller

levees further from the river would reduce construction cost and would reduce

impacts to the stream by discouraging the use of stream materials.

iii. Multi stage channels are mentioned as a further variation. “Normal” lower flows are

contained within a relatively narrow channel with the higher flows carried by the

wider, leveed floodplain. An equivalent practice is to cut “berms” adjacent to the

stream to increase the flood capacity of the immediate floodplain.

4.4 Ecological and environmental information

The scoping report for the emergency rehabilitation (DWAF, 2007) contains regional and local

overviews of the biophysical environment. A key recommendation is that a full EIA should be

undertaken if a relief channel with a weir at the upstream end is implemented as the preferred

rehabilitation measure.

4.5 Socio-economic information

The assessment of economic impacts will be conducted at the local scale. Previous studies as well as

the fieldwork visit conducted have shown that, in the local context, the main stakeholders and

economic activities in the project area affected by the river diversion are the irrigators who develop

their farming activity in Catuane and the Ndumo Game Reserve (NGR). For this reason, efforts will

focus on local scale assessments where the irrigated agriculture and the NGR rely on water use issues.


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For this first stage, the works carried out focused on gathering secondary data, more specifically a)

desktop survey to place the local area within a regional context, b) field visit to the breach to identify

potential stakeholders and c) a literature to identify the main potential economic activity in the

project area.

The purpose of the economic analysis is to make decision-makers familiar with the economic context,

and to provide baseline of information against which future changes can be measured. The baseline

will need to examine possible economic scenarios (breach alternative solutions). Ideally, a profile

would provide information from which indicators can be derived to assist in measuring change

directly attributable to any changes in policy and associated plans. The two main activities to be

developed in the next phase of the project will be the quantitative economic impact analysis of the

breach and the costs analysis of the alternative solutions proposed. With these activities the study

will respond to the following questions:

a) What is the economic impact of the river diversion on the irrigated agriculture?

b) What is the economic impact of the river diversion in the Ndumo Game Reserve?

c) What is the economic cost of the different river breach rehabilitation solutions?

The section below focuses on the presentation of the methodological aspect that will be considered

to achieve a successful impact analysis of the project.

4.5.1 Methodology

The economic assessment of this study will investigate both successes and failures (positive and

negative economic impacts) related to the diversion.

Primary and secondary data sources will be consulted in order to identify the changes in farming

systems (irrigation agriculture swift to rain-fed agriculture) and in the NGR that occurred before

implementation of the diversion, as well as to assess their economic implications at the level of the

community and the household. A study will be carried out among households from Catuane area in

order to describe the farming systems currently practised in the area, as well as the activity level

(economic performance). The study will also investigate potential economic implication of the impact

of the breach in for the NGR.

A stakeholder analysis will reveal target informants who may have access to relevant secondary data.

These informants may include sample households, local leaders, representatives of the Department

of Agriculture and Rural Development and the NGR. Such data will help to improve the overall quality

of information obtained for the project, as well as the development of the most suitable participatory

model for identification of the best solution.

Primary data will be collected from a questionnaire, checklist, observation and interviews. Among

these, a structured questionnaire and checklist will be used as tools for data collection: a)

questionnaire survey will be used at the household level to collect basic information on water use of

the household, household economic situation and potential benefits from the project (questionnaire


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will focus on irrigators), b) key informant interviews will be conducted to gain information from

district and NGR.

The primary information will be obtained from a survey of farmers in the study area and in the NGR. A

questionnaire will be used to collect information about the economic characteristics of the farmers,

and their crop plans as well as the economic performance of the Game Reserve. The information

collected will enable us to characterise the diversity of farms in the area and to establish the farm-

types in the district. The survey will be also the main source of information for the calculation of the

economic indicators that will be selected for project.

Descriptive statistic tools and impact indicators (quantitative analysis) will be used in this

investigation: these will be used to analyze the results. Tools used will include frequency analysis,

percentage, means, cross-tabulation, median, standard deviation, as well as statistical graphs and

charts and economic indicators calculation. On the other hand descriptive statements (qualitative

analysis) will be used to substantiate quantitative data, particularly from the data obtained in

interviews with key informants, group discussions and field observation.

4.5.2 Cost analysis of alternative solutions

The cost analysis will be the process of identifying the necessary resources to implement the

alternative proposed solutions. The cost analysis determines the quality and quantity of resources

needed.

4.6 Land and topographic information

4.6.1 Topographic information

The South African Department of Water and Environmental Affairs provided a LIDAR survey of the

river and surrounds flown on 30th August 2007. The survey covers an area of roughly 3.5 km wide and

16 km along the Usuthu main channel. The breach site is located about 7 km downstream of the

western boundary of the survey.

The NASA / Japan 30m digital elevation model has been obtained and provides topographic

information for general use upstream and downstream of the LIDAR survey. This data is not suitable

for detailed hydrodynamic modelling.

4.6.2 Aerial Photography

All available South African aerial photography were obtained from the Chief Directorate: National

Geo-spatial Information of the South African Department of Rural Development and Land Reform (


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Table 4-2).


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Table 4-2 : Aerial Photography

Job Date Scale

167 1942

362 1955 1 : 12 000

470 1962-1964

661 1969-1970

751 1975

809 1978 1 : 150 000

942 1991 1 : 50 000

It has not yet been possible to collect the Mozambican aerial photography flown in 1982. The

consultant will source this and other available data during the main phase of the study.

4.6.3 Satellite Imagery

The aerial photography has limited use for the study as the latest photography were flown in 1991,

before the major floods during the wet seasons of 2000-2002, and well before the occurrence of the

breach. To supplement the aerial photography, Landsat 7 ETM satellite images were obtained from

the USGS-EROS site1 (Table 4-3).

Table 4-3 : Landsat imagery

Scene ID Date of

Acquisition

Scan Line

Corrector

Comment

LE71670792002290SGS00 2002/10/17 ON 2001 dry season

LE71670792003037SGS00 2003/02/06 ON 2003 wet season - coincides with flood peak

LE71670792003085ASN00 2003/03/26 ON 2003 wet season

LE71670792003149ASN00 2003/05/29 ON 2003 dry season

LE71670792003245ASN01 2003/09/02 OFF

LE71670792004088ASN01 2004/03/28 OFF

LE71670792010056ASN00 2010/02/05 OFF 2010 wet season – diversion known to be

active

Near infrared composites were prepared with bands 4 (VNIR), 3 and 2 to assist with water body / land

surface boundary definition.

4.7 Other information relevant to the study

The study team has access to the suite of Joint Maputo River Basin Water Resources Study

(JMRBWRS) reports, which provides regional context and background information for the current

study.

1 http://glovis.usgs.gov


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5 FLOOD HYDROLOGY AND HYDRAULICS

5.1 Scope and Objectives

The flood hydrology and hydraulics investigations have been divided into three sub-tasks. The sub-

tasks and their respective objectives are shown in Table 5-1:

Table 5-1 : Hydrology and Hydraulics Sub-Tasks

Sub-task Objective

Flood Hydrology Derive design flood peaks and hydrographs for the Usuthu/Maputu catchment

upstream of the breach site.

Hydrodynamic

modelling

Using 1-dimensional hydrodynamic modelling, route the design flood

hydrograph along the river reach upstream of the breach site to identify other

potential breach sites (low points) and to provide boundary conditions for

detailed 2-D flow and sediment transport modelling in the vicinity of the breach

site.

Using 2-dimensional hydrodynamic modelling, route design flood hydrographs

through the breach site to determine flow direction, depth and velocity profiles

at the site.

Perform 2-D sediment transport modelling to derive bed shear stresses and

sediment flow directions

Hydraulic design Based on the findings of the hydro-dynamic modelling, undertake a preliminary

hydraulic design of the rehabilitation works

5.2 Flood Hydrology

5.2.1 Scope and Objectives

In order to design the rehabilitation measures, a design flood analysis is required. Design flood

recurrence intervals (RIs) will depend on the type of rehabilitation measures that are preferred, but it

is anticipated that at least the following will be required:

• Average annual flood peaks (equivalent to a 1 in 2 year RI)

• 1 in 3 year flood peak, associated with bank-full discharge of a meta-stable system

• A flood with a RI of between 1 in 20 and 1 in 50 years, equating to a “re-set” event

• 1 in 100 and/or 1 in 200 year flood peaks to assess the safety of the preferred option (if a weir

option forms part of the solution)

Besides flood peaks, design flood hydrographs will be determined for each of the RI flood peaks.

These are required for scour analysis, as steady state scour analyses represent a “worst-case”

scenario.

5.2.2 Previous Studies

Aurecon (2009) has undertaken a design flood analysis for the Siphofaneni and Mhlatuzane bridge

designs in the Usuthu catchment in Swaziland. The Siphofaneni site is located on the main Usuthu

River upstream of its confluence with the Mhlatuzane River, while the Mhlatuzane site is located

downstream of the new LUSIP dam on the Mhlatuzane River, a large tributary of the Usuthu River.


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Both sites are approximately 100km upstream of the breach site. The following design flood peaks

were determined at the two sites:

For Siphofaneni Bridge:

• 1:50 year RI flood peak: 7 200 m3/s

• 1:100 year RI flood peak: 11 300 m3/s

For Mhlathuzane Bridge

• 1:5 year RI flood peak: 87 m3/s



A separate design flood study was undertaken for the LUSIP development. Flood peaks were derived

at the diversion point of the scheme on the main Usuthu River and are shown in Table 5-2.

Table 5-2 : Flood peak data obtained from the LUSIP study

Recurrence Interval

(year)

Peak discharge

(m3/s)

2

5

10

20

50

100

600

1 150

1 610

2 140

2 940

3 620

The 1 in 50 and 1 in 100 year RI floods determined for the Siphofaneni bridge design and LUSIP

development can be directly compared, as the sites are relatively close to each other when

considering the size of the upstream catchment. As can be seen, there is a large discrepancy, with the

Siphofaneni study providing the more conservative estimates. The reasons for the discrepancy are

not immediately obvious and further work will have to be done to establish these. Depending on the

outcome of this assessment, it is provisionally proposed that the Siphofaneni / Mhlatuzane hydrology

be used as a basis for estimating design floods at the breach site. This would have the advantage of

including the attenuated contribution of the Mhlatuzane River after routing through the LUSIP dam.

In addition, the Siphofaneni / Mhlatuzane methodology will allow for the determination of routed

hydrographs associated with the RI flood peaks.

5.2.3 Methodology

It is proposed that the previous flood hydrology (Siphofaneni / Mhlatuzane – preferred, or LUSIP –

alternative) be extended to include the incremental catchment to the breach site, some 100km

downstream. In addition, low recurrence design floods (1 in 2 and 1 in 3 year RI) will be determined

for the entire catchment upstream of the breach site. The latter will be done by probabilistic/flood

frequency analysis using a range of probability distributions. High RI floods will be determined by a

combination of:

• Regional Unit Hydrograph which uses a dimensionless regional unit hydrograph

• Probabilistic/Flood Frequency Analysis

• Empirical flood estimation (using the Francou-Rodier approach) to develop Regional

Maximum Flood (RMF) peaks. RMF flood peaks can be scaled to other large RIs.


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5.3 Hydrodynamic Modelling

5.3.1 Introduction

For this Inception report a preliminary 2-dimensional hydrodynamic model was configured for the

Usuthu River, including the breach site. The objectives of this configuration was to ascertain the level

of detail contained in the LIDAR survey and to obtain a preliminary estimate of the potential for the

formation of an alternative upstream breach site should the current breach site be completely

rehabilitated.

5.3.2 LIDAR survey of the lower Usuthu

The topographical information obtained from the LIDAR survey contained x,y and z co-ordinate data

for more than 7 million points. The meshing tool of the CCHE (NCCHE, 2009) model could not

accommodate all the available co-ordinates and the number of points was eventually reduced to one

million to allow the program to render a topographical image. The initial bed level rendered by the

program is shown in Figure 5-1.

Figure 5-1 : Ground levels obtained from LIDAR survey

In Figure 5-1 the area of interest is located within the red circle – the arrow points towards the breach

site. Initial evaluation of the survey suggests that the level of detail present in the survey is sufficient

for detailed hydrodynamic modeling even after the number of co-ordinate points had been reduced

from 7 million to 1 million.

5.3.3 Configuration of the preliminary hydrodynamic model

The area included in the preliminary configuration of the model is shown in Figure 2. The upstream

boundary is approximately 3.5 km upstream of the breach while the downstream boundary is about

2.1 km downstream of the breach. The boundaries of the preliminary model are shown in Figure 5-2.


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Figure 5-2 : Boundary of Preliminary Usuthu model

A steady-state run with a discharge of 100 m3/s was undertaken to ascertain whether the model

would in fact simulate the diversion of flow at the current breach site. The output from this run is

depicted in Figure 5-3 which clearly shows the diversion of the original river course.


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Figure 5-3 : Simulated water depth at a steady discharge of 100m3/s

5.3.4 Potential for the formation of alternative upstream breach sites as a result of the

implementation of a permanent solution

An additional run in which the current breach site is completely rehabilitated (by removing the

outflow boundary condition) was also configured to identify possible breaching upstream of the

current breach site. In this run the upstream boundary condition was moved above a well defined

historical channel to test whether the river could select this path in the event of a permanent

rehabilitation at the current breach site. A steady discharge of 350m3/s was used for the additional

run. Although the simulation domain does not include the full extent of the flood plain it should still

provide an indication of possible breaches upstream of the current breach. The extent of area

configured in the additional model run is depicted in Figure 5-4 which shows that some flow is

diverted into the historical channel. At this stage it is unclear whether the upstream breach would be

caused exclusively by the rehabilitation of the current breach and this phenomenon thus needs to be

analyzed further.


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Figure 5-4 : Potential upstream breach at 350 m3/s discharge and implementation of permanent

rehabilitation of current breach site

The detailed scenarios which will be undertaken after the inception report is accepted will be

described in the ensuing section.

5.3.5 Proposed additional runs for detailed simulation

Based on the outcomes of the above preliminary simulations of the river reach, the following further

simulations are proposed.

5.3.5.1 Additional steady state runs without the effect of sedimentation and scouring

Additional steady state runs without the effects of scouring and sedimentation will be undertaken to

identify (with more confidence) potential upstream breach sites along the river reach. For these runs

and all subsequent runs, the model extent will be expanded to include a realistic flood plain and the

mathematical grid will be refined to allow for improved interpolation of ground levels.

The outputs from these simulation runs will then be used to identify specific areas where detailed

simulation will be required. Closure of the possible breach sites could cause additional damming

upstream which could change the fluvial morphology: river shape and sinuosity. Closure should

therefore attempt to prevent diversion of small regular floods, but during large floods the full

floodplain should be available for flood flow, with the breaching “berms” acting as spillways.

5.3.5.2 Unsteady state run including the effect of scouring and sedimentation

Once it has been determined which areas would require detailed analysis, possible refinement of the

grid in this area will be undertaken (if necessary) and the inlet flow boundary condition will be

changed to reflect the shape of flood hydrograph determined from the flood hydrology task.

Sediment fractions obtained from the sediment sampling and grading analysis will then be used as

sediment boundary conditions to the CCHE model while the sediment yield will be based on the

sediment transport capacity of the river and information contained in previously-completed reports


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on the Usuthu River. Simulations will be carried out for different berm heights to limit their effect on

the main channel fluvial morphology.

5.3.5.3 Worst case scenarios

Worst case scenarios will also be analysed. These will be based on long-term steady state analyses at

the determined flood peaks including the effects of scouring and sedimentation. These simulations

will be performed specifically to obtain “worst case scenario” outputs at the current breach site and

at other sites of interest identified during the previously completed tasks.

5.4 Hydraulic Design

5.4.1 Preparatory work required for the preliminary design

The preliminary design of the rehabilitation works will require the following preparatory work to be

carried out during the main phase of the project:

(a) Besides the LIDAR survey which is available, additional surveys are required to:

• better define the channel geometry directly upstream and downstream of the breach,

and in the upstream section of the breach for a distance of about 50m.

• confirm gauge plate zero levels at the E393 (Fronteira Oest) and E7 (Catuane) flow

gauging stations.

(b) Sand samples will be taken along the length of the main channel bend in the centre of the

channel, on the banks and in the centre of the upstream end of the new channel. Grading

and hydrometer analyses will be performed on the samples.

(c) Suspended sediment samples and velocity measurements will be taken from the main and

new channels

5.4.2 Preliminary design

Concept designs will be prepared and costed at a reconnaissance level for the range of rehabilitation

measures identified in the Inception phase. (Refer to Section 8 for a list and discussion of these.)

After selection of a preferred option, a preliminary design will be prepared. The preliminary design

will form the basis for preparation of a tender for the detailed design and construction of the

permanent rehabilitation works.

The sequence of activities for this task will thus be as follows:

(a) Prepare concept designs for candidate options

(b) Selection of a preferred option by evaluation of socio-economic, environmental and cost

benefits and disbenefits (Whole team in consultation with the Client and stakeholders)

(c) Additional detailed surveys, focussed on the preferred option

(d) Completion of a preliminary design of the preferred option


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6 SOCIO-ECONOMICS

6.1 Background

About 16 km from the border with Swaziland, in a region situated on South African territory, a breach

on the Maputo River to the Banzi Pan occurred. This phenomenon, which changed the course of the

river that has been there for more than two centuries2, was first reported in August 2005 by the

Mozambican authorities to South African authorities and has become an ongoing problem. This

breach causes 11 km of the river and adjacent areas of influence to undergo irregular water flows

which worsen during the dry season to the extent that, according to some sources, very frequently

the river runs completely dry. The affected areas are mainly on the Mozambican side, in Matutuine

district, Catuane Administrative post.

In 2007 (October/November) and after lengthy negotiations an emergency and temporary solution

was piloted. It consisted of using sand bags to create a barrier that could restore the river course to

its natural flow. The emergency intervention lasted for a shorter period than what had been

anticipated. Authorities from both countries believe that emergency interventions should be put

aside and a permanent solution should be sought after. The permanent solution should be preceded

by a multidisciplinary study to investigate the problem, determine its magnitude and identify the best

engineering solution.

In line with the Terms of Reference (TOR) and the Consultant’s proposal, the Study is divided into two

phases. Phase I of the study will comprise of the investigation of the breach, which includes its impact

(environmental, social, economic, etc.) on the local communities and the implications to downstream

flows. The second phase will focus on the evaluation of potential solutions to be discussed with the

client and relevant stakeholders. In addition, after selecting a solution, the Consultant will present in a

draft design report that will include the conceptual designs of the engineering solution. The solution

will then be presented for approval by the Client and relevant stakeholders.

This document/chapter deals with the socioeconomic aspects of the study at the inception phase. It is

divided into two main parts. The first part identifies and describes the socioeconomic conditions of

Catuane Administrative Post (AP) in order to provide a broader basis for understanding the extent to

which the river breach and resulting water flow fluctuations and water deprivations affect or may

affect local livelihoods. The second part is an attempt to identify the issues in need of further

investigation to measure the impact of the breach and formulate a lasting solution. It also presents

the methodologies and tools to be developed and used to conduct such an investigation.

The document was developed on the basis of the following sources of information: (i) secondary data

review; (ii) interview to a certain number of informants; and (iii) visit to Catuane Administrative Post

and direct observation.

2 The traditional river line/course defines the border among the three countries as adopted by Berlin Conference

(1885).


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6.2 Matutuine District and Catuane Administrative Post

6.2.1 Overview

As can be seen from Figure… the affected 11 kms are located in Matutuine district and more precisely

in Catuane Administrative Post (AP). The latter is one of the five Administrative Posts of Matutuine

district. The other APs in the same district are Catembe, Missevene, Machangulo and Zitundo. In spite

of being endowed with vast natural resources, including considerable biodiversity3, Matutuine district

is one of the poorest districts in Maputo province. An indication of this could be the fact that at

present the capital of Matutuine district is the only district capital not linked to the provincial capital –

Matola – by a tarred road. Poor infrastructure (roads, water supply, electricity, communications, etc.)

and services (financial, social (health/education), etc.) are the principal factors behind the relative

underdevelopment of the district.

Catuane AP has a total area of 1,258 km² and a total of 7,158 inhabitants (about 19% of Matutuine

dstrict), of which 3,657 are male and 3,501 are female. The AP is comprised of 2 localities, Pazimane

(Catuane Headquarters) and Manhangane. The latter is situated outside the river influence while

Pazimane is directly under the river influence4 and it is the most affected by current water flow

fluctuations. Pazimane is comprised of a total of 4,338 inhabitants, which represent around 61% of

the total number of inhabitants in the entire AP, and of which 2,181 are male and 2,157 are female.

Similar to many areas of Mozambique that rely on small scale and traditional agriculture, the rivers, in

this case Maputo River, play an important role as agglutinating factors. In the absence of advanced

water management systems, including resources to transport water from the source to where it is

needed and used, people tend to concentrate around the river to obtain a multitude of benefits from

it, mainly moist soils to practice agriculture and other activities that rely on water and/or soil

moisture.

Catuane AP has 9 primary schools (5 with the two cycles (EP1 and EP 25) and 4 with only the first cycle

(EP 1)) and 2 health units classified as Type 2 under the Ministry of Health system of classification.

There is also a first aid unit in the AP (in Mabale village). The two mobile phone operators existing in

Mozambique (mCel and Vodacom) have extended their network to the area. In addition, due to its

close proximity to South Africa, the AP is also covered by the South African mobile phone networks

(MTN, Vodacom and Cell C).

The headquarters of the AP is served by a small piped water supply system that abstracts water from

Maputo River and supplies 2-3 standpipes. It is only the house of the Head of the AP that has water

house connection. There are also seven boreholes with hand pumps throughout the AP with two of

them located at the AP’s headquarters. Water from these boreholes is considered brackish by local

people who prefer to use water collected directly from Maputo River for drinking.

6.2.2 Economic activities

There are no industries in Catuane AP and according to the Head of the AP in spite of the AP’s

relatively strong potential for eco-tourism there are no tourism enterprises. There are a certain

number of formal shops scattered around the AP which mainly sell groceries. These are

3 Maputo Special Reserve (MSR) is situated in Matutuine district. There is a plan to integrate MSR into the

Lubombo Transfrontier Conservation Area (LTFCA), which comes as recognition of the rich biodiversity of the

entire region comprising parts of Matutuine district, South Africa and Swaziland. 4 Defined as the geographic spaces that could be affected, directly or indirectly, by events related with the river. 5 These are the two cycles into which the seven years of primary education are subdivided in Mozambique. EP1

corresponds to the first 5 years while EP2 to the final 2 years.


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complemented by several informal selling points which also provide basic consumer goods including

clothing.

Like most of the areas in Matutuine district, around 80% of the people in Catuane AP and the study

area rely on subsistence agriculture for a living. The farming systems embraced by these people

integrate plant and animal production and are supplemented by a series of other income generating

activities. These activities include exploration of forest products (for construction, fuel wood,

charcoal, etc.), informal trade, work in South Africa, Swaziland, Maputo province and the Greater

Maputo area (namely Boane, Matola and Maputo City). Fisheries in Maputo River and Phandene Pan

have a certain weight in local economy. The subchapters below provide additional descriptions of the

main economic activities in Catuane, and particularly those activities that have stronger relationships

with water from Maputo River.

6.2.3 Agriculture in Catuane AP – the predominance of the family sector

6.2.3.1 Commercial farming

Catuane is endowed with rich soils for plant production and abundant pastures for animal production,

but historically most of its land has been perpetually exploited by the so called “family sector”.

According to the Head of the AP, recently, land has been newly conceded to commercial farmers who

manifested interest in practicing both plant and animal production in different areas of the AP. More

details about these concessions will be provided at a later stage. However, most of these concessions

remain dormant6. Apparently there are only three commercial farmers/farms that seem to be using

the land in either of the different ways, namely:

(a) FOCUS 21 is a company that has land use rights for 3,000 ha of land which was part of a state farm

in the 1970s/1980s. Of the 3,000 ha, only around 10 ha have been used for plant production, mainly

for commercial vegetables. The rest of the land remains idle or is used as a pasture. FOCUS 21 has

more than 100 heads of cattle, 90 goats and 130 sheep as well as more than 100 pigs. This farm is

under Maputo River's direct influence as it pumps water from there. FOCUS 21 has experienced

serious problems in terms of accessing water during the dry season. They have had to dig for water in

order to be able to pump it to the farm. Alternatively, they also have boreholes throughout the farm

mainly to provide groundwater for their animals. Should the water table be altered as a consequence

of the river breach, the availability of this groundwater source may also be affected.

(b) Três Rios (Three Rivers Farm) is a 1,000 ha farm that started operating about three years ago. The

first two years were dedicated to preparatory activities and at present the farm has planted 62 ha of

litchis for export in an area planned to reach 200 ha shortly. The remaining 800 ha is reserved for

livestock. The land use rights have been issued on behalf of a South African national. Three Rivers

Farm is a clearly well established operation, which can be seen as setting a good example for possible

ways of developing rewarding agricultural initiatives in the area. In addition to the foreign currency

that it is expected to generate through the export of its products, the farm provides 50 permanent

jobs to local people and during the harvesting season it will provide between 1,000-2,000 seasonal

jobs. This will certainly have considerable positive effects on the local economy and eventually

reducing the need for the local labour force to emigrate.

The farm gets its water from Phandene Pan, which is linked to the Maputo River water system. Each

litchi tree requires 20 to 25 litres (l) of water a day. The 200 ha of litchi plantations, as is planned, will

have room for around 48,000 litchi trees, which will make the total water demand to roughly 960,000

6 This is not exclusive to Catuane area. This trend can be found in many other areas of the country where lack of

capital and other conditions explain that land concessions for agriculture are rarely used for such.


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to 1,200,000 l a day, when farm operations reach their full scale. Although not necessarily excessive in

itself, this is seen by local authorities as increased pressure on Phandene Pan, which is a source of

water for many other uses such as fishing, animal watering, bathing, washing, fauna, etc. It is

assumed, that when Maputo River runs dry the pan provides alternative sanctuary to hippos and

crocodiles that run away from the river to the lake. In turn, this brings additional pressure to local

farming activities as hippos invade surrounding farms in search for food. As a way of curbing what is

perceived as pressure that may become unsustainable over time, the AP authorities have been trying

to establish a committee to manage the use of water in Phandene Pan. The ability of such a

committee to work effectively and contribute to better water management systems remains

questionable and this in itself can be seen as an open door for more serious problems in the future,

especially if the water cycles in the area continue to be negatively influenced by the breach of the

Maputo River upstream.

(c) Jantino Farm is a 1,500 ha concession that operates approximately in the same fashion as FOCUS

21. In the course of the initial visit it was not possible to gather more details about this farm. This will

be done during the detailed investigations.

There are other smaller commercial farming operations being carried out by local cooperatives and

associations such as: Ndlala Association of Farmers (Associação dos Camponeses de Ndlala);

Malanchote Association and Telmina Pereira Change Association (Associação Força da Mudança -

Telmina Pereira).

As indicated above, commercial farms following the Three Rivers or the FOCUS 21 model can be

expected to increase in the years to come as more concessions are activated and/or made. This will

be associated with increased water demand directly from Maputo River, Phandene Pan, and/or

groundwater.

6.2.3.2 Small scale family sector farming

Small scale agriculture, in the form of plant and animal production, is the dominant activity or

occupation in the Catuane area. Local communities rely on agriculture to survive, to interact with and

make exchanges with the outside world, and to have access to other means of subsistence.

Some of the aspects that define the practice of agriculture in the area, which are typical of the so-

called “family sector” in Mozambique and most of Sub Saharan African countries, are replicated in

Catuane and are characterized by:

� Cultivation of very limited areas. Between 0.8 and 1-5 ha is the common size of most of the

farms (MAE, 2005).

� Use of farming technologies that are rudimentary. Cultivation is primarily undertaken using

hoes and virtually no external inputs, such as improved seeds, fertilizers and chemicals are

used.

� Poor and/or inadequate soil and water management technologies and practices.

� Minimizing risk through crop diversification, which takes place in a variety of ways and areas:

o Growing several crops and the dominance of mixed intercropping (in the same farm

maize, cassava, sweet potatoes, sugar cane, banana, etc. can be found – see

Figure...);

o Preferring to grow two or more consecutive crops rather than a single one of a longer

cycle, even if the potential total yield is higher for the latter, in order to obtain

advantage of moisture availability during the short rainy season; and,

o Growing crops in as many diverse environments as possible (e.g.

topography/relief/soil), e.g., in sandy flat areas, in medium textured alluvial deposits


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of slopes (transition zones), in the fine textured dark coloured soils of the river beds

(baixas) and in open valleys and alluvial soils.

The end result is a combination of plots of different crop preferences on different soil types and, each

with different fallow and cropping patterns. There is also a great level of gender and age

differentiation in labour distribution. Men and boys normally engage in the production of cash crops

(vegetables in this area7) while women and girls are active with food crops (maize, rice, cassava,

beans, sweet potatoes, etc). In terms of animal production, boys are actively involved in goat/sheep

and cattle rearing. It should be mentioned that in Catuane, animal production (cattle, goats, sheep

and pigs) is perceived as being the dominant activity in the family sector production system. Plant

production plays a complementary role. The area has a strong tradition of livestock production.

Possessing cattle, goats and sheep is seen as a symbol of high status.

The project area is in general very rich in terms of water resources because of the presence of

Maputo River, Phandene Pan and other smaller water courses (??? Name them). The land bordering

these water courses (baixas) is used extensively to practice agriculture, mainly as a way of

counteracting the effects of recurrent droughts in other areas. It is mostly common to find people

farming around the margins of water courses and particularly Maputo River (see Figures….) even

though they live a distance away from those margins. Under these circumstances, agriculture is

practiced throughout the year and in normal yearly weather conditions, i.e. not extremely dry or wet,

this happens with a relatively high degree of success. There are indications that reduced water flows

during the dry season, which seem to have worsened by the river breach, are threatening to change

this pattern. Apparently the perception is not yet generalized. Focus groups discussions and

discussions with informants with a better historical perspective may be needed to make a more

concise assessment of the extent to which the breach is seen as an aggravating factor to the reduced

water flows during the dry season.

Production is used mainly to meet household food requirements but at times it finds its way to the

market and is converted into cash and/or exchanged with other products needed at the household

level. There is no strict line between food and cash crops. It all depends on surrounding circumstances

and mainly on the supply and demand at a given point time.

Employment in existing agricultural and commercial ventures and remittances from emigrated labour

are other sources of income used to sustain the families. Poles and reed are used by local residents

for building and for firewood as well as for making charcoal. Fuel wood and charcoal are the main

domestic sources of fuels. These are also traded to generate cash. Indications are that Catuane was

an important source of fuel wood and charcoal to Boane, Matola and Maputo in the past. However,

extensive depletion of these resources due to over exploitation has changed the situation in the last

few years.

6.2.4 Fisheries

38 fishing licences have been issued by local authorities to benefit an equal number of authorized

fishing operators in Phandene Pan although it is believed that there are more operators who operate

without formal licensing. Fishing in Maputo River does not require any licensing and is practised by

many families, particularly during the wet season. Fish products play an important role in the local

economy on one hand as a source of income and on the other hand as the main source of animal

protein in local people’s diet, the use of other meat products is limited due to cultural barriers. Mainly

through Phandene Pan Catuane is known for being a significant supplier of fish products to Boane,

Matola and Maputo. The business can be estimated to generate ... MT on a monthly basis. There are

7 There were informal references of extensive cultivation of cannabis in the area.


28

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mainly two species being caught using nets and fish hooks namely tilapia - Mozambique Tilapia

(Oreochromis mozambicus) and sharptooth catfish (Clarias gariepinus) It is mainly during the wet

season and when there is water that Maputo River also plays a certain role in the supply of fish.

Anecdotal evidence indicates that when there is enough water running the river is highly productive

to the extent that even women and children manage to catch fish using cloths and other non-fishing

tools.

6.2.5 Other social activities related with the river water flows

As indicated above due to the brackishness of local groundwater, local people prefer to drink water

collected directly from the river than from the boreholes. Consequently, in spite of being unsafe

water from Maputo River plays an important role in supplying drinking water in Catuane area. River

water is also extensively used for washing and bathing. Local women and children take their clothing

and other home utensils to wash them directly at the river. In addition to meeting material needs this

practice also meets other socio cultural needs as it provides an opportunity for social gatherings

where women exchange information and engage in many other forms of social interaction. It is

reported that when the river runs dry they dig its basin to get drinking and washing water but

depending on the extent of dryness this practice becomes less feasible to get water for washing.

During the first visit it was not possible to get a clear direction from local informants of the extent to

which this phenomenon is perceived has having worsened due to the river breach. People seemed to

be more sensitive to the effects of water releases from Pongola Dam/River than the possible effects

of the breach on local water sources. It may be necessary to meet more people and to restructure the

questions and the way discussions are conducted in order to get people to come up with straight

forward and elucidative answers.

6.3 Issues to investigate and methodologies and tools to be used

Preliminary indications are that the normalization of Maputo River flow plays an important role in

normalizing a wide range of social and economic activities in Catuane area in the way that these

activities are at present and might be in the future. The main issues to consider are:

� Pazimane Locality and Catuane headquarters, which are the most directly affected by the

river breach, occupy an important position in the entire Catuane AP and Matutuine district as

socioeconomic units. This importance can be expected to grow as Mozambique and

Matutuine district normalize their life and develop;

� Phandene Pan is the main source of permanent water in the area and it meets most of the

water needs in the AP throughout the year. As more developments take place in the area the

importance of this water source can be expected to grow and diversify. This brings along

water management and sustainability issues. Among other measures there is a need to

ascertain the extent to which changes in Maputo River water flows, due to the breach, have a

stake in the recharging of this significant water deposit in the medium to long term. The

results will be essential in determining the type of solution that is most suitable for the

breach;

� Existing and potential commercial and family sector plant and animal production operations

seem to be heavily dependent on the normalization of the river flows. In the long term they

might be negatively affected by the dryness associated with the river breach. The same seems

to apply to the recharging of the water table in the area;

� Abnormal river flows may have negative impacts on important socioeconomic activities such

as fisheries (in both Phandene Pan and along Maputo River), drinking and washing water and

related activities;


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� In the longer term changes in river flows/course may affect to adoption of the specific stretch

affected by the breach as the border line between Mozambique and South Africa: This brings

in a political dimension to the breach.

More interviews and discussions with local people and groups, especially with those who can bring a

historical element to the effects of the breach on local livelihoods, seem to be necessary. The initial

interviews were not conclusive.

Evidence collected from local people and groups needs to be supported by secondary data, mainly

imagery, which could document changes or lack of them in the last 50-70 years.

Table 6-1 : Maputo/Usuthu River Breach - Preliminary List of Contacts

N.º Name Institution/Company Position Contact

(phone/mobile/email)

1 Hermenegildo

Mahanjane

Catuane

Administrative Post

Head/Chief of

the AP

+258 82 894 3450

2 Amosse Ndlovo Catuane Fisheries

Association

President +27 82 767 9237

3 Eugenio Chibocho

Mandlate

ARA Sul Hydrometric

station reader

+258 82 272 0893

4 Johan Nienaber 3 Rios Farm Farm Manager +27 83 305 4470

5 Reginaldo Mandlate Focus 21 Agrarian

Technician

+258 82 715 1294

6 Elizabeth Mandlate Focus 21 Assets Manager +258 82 531 8270


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7 PRELIMINARY THOUGHTS ON THE REASONS FOR AND

CONSEQUENCES OF THE BREACH

7.1 Cause of the breach

7.1.1 Introduction

While establishment of the cause of the breach is not central to the current study, it could inform the

approach to the design of the permanent works. If, for example, it could be proved that the breach

was initiated mechanically, this would suggest that the aggradation of the main river downstream of

the breach may not have been the primary cause of the breach and that construction of weir to

contain low RI floods in the main channel (i.e. a re-designed version of the previous emergency

rehabilitation option) would be adequate on its own. Conversely, a “natural” breach would suggest

that additional work, perhaps in the form of a multi-stage main channel would be required to

increase the bank-full capacity of the main channel downstream of the breach.

7.1.2 Timing of the breach

Water levels measured at station E7 Catuane show dry season water levels of just over 1 m depth

between 1995 and 2002 . Beginning in the dry season of 2003, water levels drop to near zero or zero

in every dry season.

Figure 7-1 : Water Levels at E7 Catuane

To determine a more exact timing of the breach, a double-mass plot of average monthly water levels

at station E393 Fronteira Oest (near the Swaziland border, upstream of the breach) and E7 Catuane

(downstream of the breach) was prepared (Figure 7-2). An inflection can be seen to occur between

May and September 2003, during the dry season. This, and the fact that water levels at E393 during

the preceding wet season were the lowest in the 1995-2010 period suggest that there is a possibility

that the breach was mechanically initiated, provided that systematic measuring station errors are not

the cause of the inflection.


31

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Figure 7-2 : Double mass-plot of average monthly water levels

In an attempt to confirm the timing of the breach, near infrared composites of Landsat images

acquired around 2003 were inspected to detect the presence of water in the new channel. This

exercise was inconclusive, as water in the new channel can only be detected with certainty during

high flow periods, as the composite image acquired on 25 February 2010 shows (Figure 7-3).

Without further quality checks on the measured flow levels (and rating tables and derived

discharges), and other supporting evidence, it is not possible to make a firm conclusion on the cause

of the breach. It is hoped that the hydrodynamic modelling that will be undertaken during the main

phase of the project will shed some more light on this issue.


32

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Figure 7-3 : Near infrared composite - 2010/02/25

7.2 Failure of the Emergency Rehabilitation Works

The design report of the emergency rehabilitation works has particular relevance to the current

study. At first reading the design principles appear to be sound and may be of use in the design of the

permanent solution. However, further work is required to establish the reasons for failure of the

emergency works:

• If possible, the discharge and weir overtopping height at the time of failure will be established

from the measured flow record at E393 and a hydrodynamic model simulation

• The design engineers will be consulted to obtain their views on the reasons for the failure

• It must be established whether the backwater effect of the sediment build-up downstream of

the breach was taken into account


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8 POTENTIAL REHABILITATION OPTIONS

8.1 Selection of Rehabilitation Options

An initial set of rehabilitation options have been identified during the course of the Inception phase.

These are:

(a) Alleviation of socio-economic impacts without river rehabilitation. This option would entail

water supply to affected communities, perhaps from groundwater, and accepting the status

quo regarding the new channel. It is this study’s view that this option should be ruled out due

to the following flaws:

• The international boundary will have to be redefined

• According to discussions with Ndumo Park management (Ferdie Meyer, Pers Com)

increased flooding in the northern section of the park as a result of the breach

prohibits tourism and game patrols to the area for prolonged periods of time;

• Existing information indicates that the massive flow of water into the Banzi Pans have

created a rapid flow channel at the outlet and there is evidence of sediment built up

in large parts of the pan. This is likely to have long term environmental consequences

and reduction of biodiversity.

Furthermore, it is understood that the Client parties have already come to agreement that

the river should be returned to its original course by means of rehabilitation. This was

demonstrated by a joint financed initiative for emergency rehabilitation of the breach.

(b) A re-designed emergency rehabilitation option, i.e. construction of a weir to contain low RI

floods (1 in 2 to 1 in 3 year RI) in the main channel, allowing relatively frequent overtopping

into the new channel.

(c) As for (b), but with river training downstream of the breach site to increase the discharge

capacity of the main channel. Variations on this option are:

i. Excavation and protection of a multi-stage channel downstream, and using the locally

borrowed material to plug the breach

ii. Excavation and protection of a multi-stage channel downstream, and construction of a

concrete gravity weir with a jet-grouting foundation in the mouth of the new channel.

During the Inception Phase, work has commenced on the concept design of Option (c)(i), and the

option is described in Section 8.2. It must be noted that the fact that this option is described in the

Inception Report, and no others, is purely due to programming, and does not imply a preference for a

particular solution.

8.2 Details of potential rehabilitation using locally borrowed material

(Option (c)(i))

The rehabilitation of a meandering river is complex and might require several trials before a final

solution is found. This is due to the fact that modification of the river flow regime will result in new

dynamics, hence a search for a new equilibrium that is very difficult to predict. When using

conventional building materials there is also the risk that in a new equilibrium situation the structure

will be displaced as compared to the new main river channel. There are experiences around the world


34

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showing the benefits of using local materials in repairing erosion and soils instability problems. In the

case of the Usuthu breach the team investigated the potential of application of natural materials in

solving the problems. This solution concentrates on plugging the breach and retraining the river in the

downstream section to work again as a main channel.

The river section in the vicinity of the channel diversion, about 1 km upstream and 1 km downstream,

was investigated. The lowest levels of the river bed do not form a straight channel but the flow of

water meanders from right to left and vice-versa. The slope of the river bed is in the order of 1/1000.

Downstream of the channel diversion the river bed is irregular in shape and in levels. From

observation it is possible to see that there is an increased deposition of sands on the river bed after

the diversion while in the channel diversion there is an increased erosion/scour. The drawings given

the information presented here are given in Appendix A.

The starting point of the intervention is to reinstate the free flow of the river and avoid the diversion

of the water that already occurs at present even for very low levels of river flow, approx. 0,60 m. To

reinstate the river flow, there are a few measures that should be geotechnically considered:

1. Reshape the riverbanks

2. Dredge the river bed, in particular downstream of the river diversion

3. Rebuild the river bank where erosion occurred to a level that only high flows (such as in high

floods) will overtop and enter the diversion channel.

To better understand the river behaviour the longitudinal profile of the river was drawn. We selected

the lowest levels of the river bed for this purpose. The profile is shown for a length of 1,500 m along

the river and 280 m along the diversion channel. River cross sections were plotted and we compared

the area available for the free flow of water. In order to ease the flow of water the left bank of the

river should be excavated. Because of the severity of the sediment built-up and the fact that the plug

that is proposed will take some time to consolidate, it might be advisable to make room for additional

flow of water by constructing an additional excavated channel as a shortcut.

In the proposed design both the plug and the reworked river channel and river banks we adopted a

slope of 1:10 that compares well to the measured natural slopes of 1:8.

The economic solution for the works that are proposed will be achieved through an optimal

combination of cut (at the river bank) and fill (channel diversion). As said before the left river bank

will be excavated and the soil resulting from the excavation will be used to build an extensive

embankment to block the entrance to the diversion channel. The topsoil should be removed and piled

for future use for re-vegetation of the surface and improve resistance. From km 0+719 to km 0+960

we calculated the excavation volume to be in the order of about 5,000 m3. This material should be

used for filling the plug and a good section of the diversion channel. From km 1+060 to km 1+480 the

riverbed should be dredged and we calculated the volume to be removed to be in the order of 4,500

m3. This soil material should be spread on the riverbanks by mechanical or manual means and special

care should be enforced to reduce the impact on the existing vegetation and animal life.

The embankment to be built to partially fill the diversion channel, as shown in the respective drawing

is about 4,500 m3. The sands that are placed do not need a controlled compaction. The traffic

compaction is enough. The slopes of this embankment were selected in order to minimize the erosion

due to running water. All top soil removed from the riverbanks should be carefully preserved and

placed on the fill to create a natural protection against erosion.


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2010/04/29

To allow more stabilization of the slopes (margins) on the diversion channel, on the stretch after the

landfill, it will be necessary to cut about 1,000 m3 of the existing embankments of the actual diversion

channel.

If it is decided to build an additional channel (recommended) at the left river bank, this could be

achieved by removing about 14,520 m3.

The rational of this intervention is that the adopted permanent solution will maintain the original

functioning of the section of the river as described under geomorphology section. This means during

high floods the river diversion will be laterally fed through the existing natural channels that develop

during overtopping of the banks.


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9 PROPOSED APPROACH AND DELIVERABLES

The project proposal contains a broad description of the approach and methodology for undertaking

the work. Work done during the inception phase and the information collection and assessment has

brought issues to the fore that necessitates refinements to the approach. Rather than repeating the

approach in the original proposal, the remainder of this Section describes the refinements that are

required.

9.1 Phase I activities: Preliminary design

9.1.1 Step 1 (a) : initial discussions for problem definition

In liaison with the TPTC, existing information and data has been collected, and interviews with a

several stakeholders have been completed. These include ARA-Sul, members of the public in the

Catuane area and Parks management of the Ndumo game Reserve. Additional consultations are

required with DWAF design staff and DWAF Kwazulu-natal. These and other consultations will

continue through the course of the project.

9.1.2 Step 1 (b) : preliminary site investigations, and 1(c) : investigation of failed temporary

solution

A preliminary site investigation has been completed, and supplemented by a review of the scoping

and design reports that were prepared for the emergency rehabilitation works. Additional work that

has been identified include:

• Hydrodynamic modelling of historical flows around the time of the breach to estimate

overtopping height.

• Collection of sand samples for grading and hydrometer analyses

• Additional ground surveys that will be required (Section Error! Reference source not found.)

for hydraulic design

A preliminary list of rehabilitation options have been identified (Section 8) for assessment, short-

listing and design during the remainder of the project. One potential option was described in more

detail and will give the opportunity to the TPTC and Task Team to select the options for detailed

analysis.

This inception report is based on the findings of Steps 1(a) to (c)

9.1.3 Step 1 (d) : understanding the socio-economic and environmental consequences of the

breach

Sub-task (i) of this phase has been completed and entails a description of past, current and expected

uses of the river and associated resources.


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2010/04/29

Sub-task (ii) of this phase will commence after the Inception phase, and will consist of an assessment

of socioeconomic impacts associated with the river diversion. This work will be used to expand the

preliminary list of alternative rehabilitation options, and a joint workshop with the client will be

conducted to select the preferred solution.

9.2 Phase 2 : Design of intervention measures

The design referred to in this study will be sufficient to allow a decision to be made for the permanent

solution of the problem. As a result once a decision has been made there will be a need to

commission a study for the detailed design of the measure and this can follow one of the following

options:

• Design and build; where a contractor with required qualifications is hired to detail the design

provided by this study and implement them under independent supervision.

• Commission a detailed design and thereafter issuing bid for construction.

Detail design will required extensive geotechnical survey of the site to design the foundation and also

a good analysis of existing construction materials on and around the site that will be used for

construction.

The geotechnical prospection of the site requires heavy machinery that can not be mobilized at this

stage of the design. There are environmental implications that need to be considered in the process

hence, it is advisable to include this aspect of the design in the construction phase when a

environmental impact assessment and guidelines for mitigation measures have been concluded.

9.2.1 Step 2(a) : Flood Hydrology

It is proposed that the approach to the Flood Hydrology component of this task be modified to some

extent. It is proposed to make use of the recently completed study for the Siphofaneni/Mhlatuzane

bridge flood hydrology, and to extend this work to include the incremental catchment to the breach

site, some 100km downstream. In addition, low recurrence design floods (1 in 2 and 1 in 3 year RI)

will be determined for the entire catchment upstream of the breach site.

It is proposed that flood peaks and associated hydrographs be determined for the following

recurrence intervals:

• Average annual flood peaks (equivalent to a 1 in 2 year RI)

• 1 in 3 year flood peak, associated with bank-full discharge of a meta-stable system

• A flood with a RI of between 1 in 20 and 1 in 50 years, equating to a “re-set” event

• 1 in 100 and/or 1 in 200 year flood peaks to assess the safety of the preferred option (if a weir

option forms part of the solution).

9.2.2 Step 2(b) Hydraulic analysis

The first stage of the Hydraulic component of this task, which focuses on the acquisition of

topographical surveys, aerial photography and satellite imagery, as well as hydrodynamic model

configuration, is ahead of schedule. Much of the data has been obtained, including a LIDAR survey of

the area provided by DWAF. An initial hydrodynamic configuration has been completed and used to

identify possible additional breach sites.

Configuration of the hydrodynamic model will be refined by calibration against measured levels and

flows.


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The calibrated model will then be used to perform the following analyses:

• Additional steady state runs without the effect of sedimentation and scouring to identify

(with more confidence) potential upstream breach sites along the river reach. The outputs

from these simulation runs will then be used to identify specific areas where detailed

simulation will be required.

• An unsteady state run including the effect of scouring and sedimentation in the areas that

require detailed analysis. Simulations will be carried out for different berm heights to limit

their effect on the main channel fluvial morphology.

• Worst case scenarios will also be analysed. These will be based on long-term steady state

analyses at the determined flood peaks including the effects of scouring and sedimentation.

9.2.3 Step 2(c): Hydraulic Design

Concept designs will be prepared and costed at a reconnaissance level for the range of rehabilitation

measures identified in the Inception phase. After selection of a preferred option, a preliminary design

will be prepared. The preliminary design will form the basis for preparation of a tender for the

detailed design and construction of the permanent rehabilitation works.

The sequence of activities for this task will thus be as follows:

(a) Prepare concept designs for candidate options

(b) Selection of a preferred option by evaluation of socio-economic, environmental and cost


(c) Additional detailed surveys, focussed on the preferred option

(d) Completion of a preliminary design of the preferred option

9.3 Step 3: Floodplain Management

No changes to the original proposal are envisaged at this stage.

9.4 Step 4: Management of Reinstated Flow Conditions

No changes to the original proposal are envisaged at this stage.


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10 PROPOSED WORKPLAN The work plan has not changed much since the signing of the contract. There three key components

of the study were identified during the inception phase, namely (i) the geomorphologic analysis; (ii)

the hydrodynamic and sedimentation analysis and (iii) the geotechnical analysis. These three

components will impact on the progress of the project depending on the implementation schedule

and the difficulties in accessing the relevant data. The team has updated the work schedule as

follows:

• Complementary socio-economic investigations May-June 2010

• Geotechnical sampling and survey June-July 2010

• Flood Hydrology: May - June 2010

• Flood Hydraulics:

o Prepare concept designs for candidate options May – June 2010

Selection of a preferred option by evaluation of socio-economic, environmental and cost


July 2010

o Additional detailed surveys, focussed on the preferred option

July – August 2010

• Completion of a preliminary design of the preferred option August – September 2010


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11 PROJECT MANAGEMENT

11.1 Introduction

The project is organized to be implemented in close cooperation with the client; in this case the Study

Team and DNA (acting on behalf of the TPTC) will collaborate closely for successful implementation of

the project. For this assignment the TPTC has established a Task Team of technical competence that

will review the results of the study at various stages. The reports produced during the course of the

assignment will benefit from their specialist comments and discussions during presentations. The

consultant is aware of the high expectation and uncertainty involving the study and is prepared to

organize meetings and discussions to map out all queries and potential flaws that hinder progress or

affect the good working environment between parties. A key component of this study is the selection

of a permanent solution that will take into account the needs of all parties while at the same time

avoiding negative consequences to the people and surrounding environment.

Thus the success of this project is dependent on more than the design of a good technical option; it

must also include all contributions brought by the client and its representatives.

The study is commissioned by TPTC, while the PRIMA office is responsible for administrative

management. The National Directorate of Water in Mozambique (DNA) is the legal entity

representing the client in the contract.

11.2 Communication

The consultant team is managed by the Team Leader Mr. Dinis Juízo and Deputy Team Leader Mr.

Hans Beuster. Their respective location in Mozambique and South Africa is of advantage to this

project, providing rapid contact with the clients in both countries to get information and organize

interaction as required.

The Team Leader will at all times ascertain that:

• Team members have clear objectives for the work to be done

• Focus on production of milestones and key deliverables of the project

• the correct problems are addressed

• clear conclusions are drawn

• the technical quality of the work is of highest international standard

• the Client is continuously informed of all significant project implementation matters, and in

particular, items requiring the Client's approval.

• questions requiring decisions by the Client are forwarded clearly and as early as possible.

The Team Leader and Deputy Team Leader will liaise closely with the PRIMA Programme

Manager and Programme Co-ordinator, as required, to ensure that PRIMA is well informed on

progress, to coordinate technical aspects of the project, to deal with any administrative

matters and to request assistance with data collection as required.


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11.3 Reporting

The results of the study on this project will be presented in reports that correspond to deliverables as

follows:

• Inception report – hereby presented.

• Progress report, thereafter every month for the duration of the assignment.

• Draft Design Report – 6 months after commencement of the assignment.

• Final Draft Design Report – 7 months after commencement of the assignment.

All reports will be submitted to the Client in English in draft for comment. Comments will be discussed

with the Client and incorporated into the Final Reports. Fifteen days will be allowed for review of

supporting reports and twenty days for review of the Final Draft Design Report.


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12 REFERENCES

DWAF 2007. Lower Usutu River - Government Water Scheme. Temporary Rehabilitation Measures –

Design Report. Internal Report Prepared by the Directorate: Civil Engineering of the Department of

Water Affairs and Forestry of South Africa. August 2007.

Wadeson, R. 2006. Lower Usuthu River - Diversion Channel Scoping Report. Report Prepared for

the Department of Water Affairs and Forestry of South Africa. November 2006.


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APPENDIX A

CONCEPT DESIGN – OPTION (c)(i)

STAX

Y0+000

‐66856.096‐2972171.209

0+020‐66845.821

‐2972188.3680+040

‐66835.547‐2972205.527

0+060‐66825.272

‐2972222.6860+080

‐66814.997‐2972239.845

0+100‐66804.723

‐2972257.0040+120

‐66794.448‐2972274.163

0+140‐66784.174

‐2972291.3220+160

‐66773.899‐2972308.481

0+180‐66763.624

‐2972325.6400+200

‐66753.350‐2972342.799

0+220‐66743.077

‐2972359.9590+240

‐66732.803‐2972377.119

0+260‐66722.530

‐2972394.2790+264.2203‐66720.362

‐2972397.9000+275.9425‐66714.940

‐2972408.2930+280

‐66713.278‐2972411.994

0+300‐66705.082

‐2972430.2370+320

‐66696.886‐2972448.481

0+340‐66688.690

‐2972466.7240+360

‐66680.494‐2972484.968

0+380‐66672.298

‐2972503.2120+400

‐66664.102‐2972521.455

0+420‐66655.906

‐2972539.6990+440

‐66647.710‐2972557.942

0+460‐66639.514

‐2972576.1860+480

‐66631.318‐2972594.429

0+500‐66623.122

‐2972612.6730+520

‐66614.927‐2972630.916

0+540‐66606.731

‐2972649.1600+560

‐66598.535‐2972667.403

0+580‐66590.339

‐2972685.6470+581.4404‐66589.748

‐2972686.9610+600

‐66575.148‐2972698.419

0+620‐66559.415

‐2972710.7660+640

‐66543.681‐2972723.114

0+660‐66527.948

‐2972735.4610+674.3575‐66516.653

‐2972744.3250+680

‐66511.104‐2972745.348

0+700‐66491.435

‐2972748.9720+720

‐66471.767‐2972752.597

0+740‐66452.098

‐2972756.2210+760

‐66432.429‐2972759.846

0+772.5205‐66420.116‐2972762.115

0+780‐66412.662

‐2972761.4950+781.4823‐66411.185

‐2972761.3720+795.3629‐66398.136

‐2972756.6390+800

‐66393.848‐2972754.874

0+820‐66375.354

‐2972747.2610+840

‐66356.859‐2972739.648

0+860‐66338.365

‐2972732.0360+864.5497‐66334.157

‐2972730.3040+880

‐66320.287‐2972723.498

0+896.147‐66305.791

‐2972716.3850+900

‐66302.479‐2972714.416

0+920‐66285.287

‐2972704.1970+940

‐66268.095‐2972693.977

0+960‐66250.903

‐2972683.7580+980

‐66233.711‐2972673.539

0+996.0817‐66219.887‐2972665.321

1+000‐66216.794

‐2972662.9161+020

‐66201.008‐2972650.636

1+040‐66185.221

‐2972638.3571+060

‐66169.435‐2972626.077

1+080‐66153.648

‐2972613.7981+096.0164‐66141.006

‐2972603.9641+100

‐66138.102‐2972601.237

1+120‐66123.522

‐2972587.5471+140

‐66108.941‐2972573.858

1+144.9207‐66105.354‐2972570.489

1+160‐66094.683

‐2972559.8351+180

‐66080.529‐2972545.705

1+196.0086‐66069.200‐2972534.394

1+200‐66066.375

‐2972531.5741+220

‐66052.220‐2972517.445

1+240‐66038.065

‐2972503.3151+252.5865‐66029.158

‐2972494.4231+260

‐66023.560‐2972489.563

1+266.4035‐66018.725‐2972485.364

1+280‐66007.871

‐2972477.1751+295.9979‐65995.101

‐2972467.5401+300

‐65991.905‐2972465.130

1+320‐65975.938

‐2972453.0871+340

‐65959.970‐2972441.044

1+360‐65944.002

‐2972429.0011+380

‐65928.035‐2972416.958

1+396.6213‐65914.764‐2972406.949

1+400‐65912.067

‐2972404.9151+420

‐65896.100‐2972392.870

1+440‐65880.134

‐2972380.8261+460

‐65864.167‐2972368.782

1+480‐65848.200

‐2972356.7381+495.9979‐65835.428

‐2972347.1041+500

‐65832.233‐2972344.694

1+520‐65816.266

‐2972332.6501+540

‐65800.299‐2972320.606

1+560‐65784.332

‐2972308.5631+580

‐65768.364‐2972296.519

1+595.9979‐65755.592‐2972286.886

1+600‐65752.397

‐2972284.4761+620

‐65736.429‐2972272.434

1+634.4913‐65724.858‐2972263.709

STAX

Y0+040

‐66317.684‐2972763.902

0+045.687‐66318.452

‐2972769.5370+060

‐66314.913‐2972783.405

0+063.6693‐66314.006‐2972786.961

0+079.5366‐66302.974‐2972798.365

0+080‐66302.974

‐2972798.8290+098.036

‐66302.974‐2972816.865

0+100‐66303.628

‐2972818.7160+120

‐66310.297‐2972837.572

0+123.171‐66311.354

‐2972840.5610+136.604

‐66309.381‐2972853.849

0+140‐66306.406

‐2972855.4850+155.045

‐66293.223‐2972862.735

0+160‐66291.651

‐2972867.4340+178.2979‐66285.849

‐2972884.7870+180

‐66286.380‐2972886.404

0+193.1876‐66290.502‐2972898.931

0+200‐66294.439

‐2972904.4910+205.2345‐66297.463

‐2972908.7630+218.9969‐66296.461

‐2972922.4890+220

‐66296.787‐2972923.438

0+228.553‐66299.558

‐2972931.5300+240

‐66295.604‐2972942.272

0+245.692‐66293.637

‐2972947.6130+260

‐66291.969‐2972961.824

0+280‐66289.637

‐2972981.6870+297.131

‐66287.639‐2972998.701

Documents

Draft Inception Report - Disaster risk reduction · Draft Inception Report Progressive Realisation of the IncoMaputo Agreement (PRIMA) Study for the Implementation of the Permanent