Bank Erosion in Mekong Delta and along Red River in Vietnam

184 Pages·2004·5.17 MB·English

Bank Erosion in Mekong Delta
and along Red River in Vietnam

Report Mission 23 November - 6 December 2003

Delft, March 2004
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Bank Erosion in Mekong Delta
and along Red River in Vietnam

Report Mission 23 November - 6 December 2003

Delft, March 2004
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Contents Main Report

Preface
Executive summary

1. Introduction
1.1 Background
1.2 Terms of reference
1.3 Composition of team
1.4 Approach
1.5 Set-up of report

2. Background information on the Mekong and the Red Rivers
2.1 Introduction
2.2 General information on Vietnam
2.2 Mekong River and Mekong Delta
2.4 Red River Delta

3 Main observations of the Mission to Mekong Delta and Red River

4. Additional technical observations
4.1 Introduction
4.2 River morphological and bank erosion aspects
4.2.1 Introduction
4.2.2 Morphology of Mekong and Red River, similarities and differences
4.2.3 Recent studies on Mekong bank erosion
4.2.4 Causes of bank erosion
4.2.5 Has bank erosion increased over the years and what are possible causes?
4.3 Prediction of bank erosion
4.3.1 Introduction
4.3.2 Present practice in Vietnam
4.3.3 Methods used elsewhere
4.3.4 Use of mathematical models
4.3.5 Need for additional studies
4.4 Geotechnical aspects
4.4.1 Introduction
4.4.2 Geological structure and effect on soil characteristics and erosion mechanism
4.4.3 Main geotechnical aspects
4.4.4 Modelling and stability prediction
4.4.5 Flow slides in sand
4.3.6 Observations and remarks from meeting and site visits
4.5 Bank protection works
4.5.1 Introduction
4.5.2 Measures to cope with or counter bank erosion and to reduce damages
4.5.3 Observations on bank protections
4.5.4 Bank protection materials and structures
4.5.5 Construction methods
4.5.6 Design manuals and guidelines
4.5.7 Recommendations for further implementation work
4.6 Response of river to bank protection works and consequences for future
4.7 Maintenance
4.8 Need for setting up of data base

5 Additional non-technical observations and capacity building
5.1 Introduction
5.2 Institutional and legal aspects
5.2.1 Introduction
5.2.2 Institutional aspects
5.2.3 Existing legislation in Vietnam
5.2.4 Need for additional legislation
5.3 Socio-economic/environmental aspects of flooding, bank erosion and counter-measures
5.4 Master planning for bank erosion mitigation and river training
5.4.1 Need for a Master Plan and a long-term strategy for bank protection
5.4.2 Master plan as part of Integrated River Basin Planning and Management
5.4.3 Elements of a Master plan
5.4.4 Some details on some components of Master plan for River training and Bank
Protection
5.5 Data and information management
5.6 Capacity building
5.6.1 Capacity building and cooperation
5.6.2 Staffing of Dike Department
5.6.3 Need for training of provincial staff
5.6.4 Use of models
5.6.5 Upgrading university curriculae

6 Proposed Action Plan 2004-2007

7 Conclusions and recommendations

References

Appendices
I Mission participants
II Contacts in Vietnam
III Mission program and schedule
IV Field visits Mekong River
V Meetings Mekong River
VI Field visits Red River
VII Meetings Red River (including Final meeting)
VIII Damage overview (collected data)
IX Supplementary informations

Contents Supplement: Short review on bank erosion and bank protection

1. Causes of erosion and failure a
2. Cliff erosion
3. Bank erosion in stable river systems
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4. Bank erosion and planform changes
5. Survey and data collection
6. Types of bank protection
7. Techniques of bank protection
8. References

List of Tables

1 Comparison of river characteristics of the Mekong and the Red Rivers
2 Advantages of including the effect of sedimentary features in the prediction methods for the
Jamuna River (Sarker & Khayer, 2002)
3 Comparison of different protection types.
4 Proposed time schedule for identified actions in the fields of capacity building in bank
protection and river training in Vietnam

List of Figures

1 Some information on flooding in Vietnam
2 Mekong Delta location, provinces and regions
3 Hydrology of the Mekong Delta
4 Flood map 1984
5 Final meeting at the Dike Department of MARD where the main conclusions from the
Mission were discussed with senior MARD/DDMFC staff
6 Faults and their possible impact on the planform of the Lower Mekong River
7 Water levels in the Lower Mekong during the year 1982
8 Flood levels Lower Mekong River
9 Some information on the composition of the Mekong Delta
10 Eroding banks along Mekong River
11 Eroding banks Red River
12 Different types of bank erosion along the Mekong River in relation to planform development
13 River planform and bank protection works along the Red River (taken from provincial map,
note that other province is not indicated)
14 Some information on flood peaks of the branches Lower Mekong River in the period 1978-
1998
15 Local bank erosion rates of the Mekong River at Sa Dec versus relative curvature (source Le
Manh Hung & Dinh Cong San (2002))
16 Prediction method for bank erosion along outer bends in the Jamuna River as an example of
the methods developed by Sarker & Khayer (2002)
17 Alluvial stratification along the Tien river
18 Procedure for evaluating riverbank stability (US Army, 1981)
19 Example of physical components of bank erosion (US Army, 1981)
20 Example of slope stability calculation for a cross section of a dike with berm and slip circle
21 Schematization of flow slides for sand and clay
22 Plan view of a flow slide
23 Physical principle of liquefaction phenomenon
24 Sa Dec slope protection
25 Serious erosion near Vinh Long
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26 Cracks in dike left bank Red river between K82 and K84 in Hung Yen province
27 Bank cracking along the Red River at location (Ha Tay province)
28 Some examples of groynes in Mekong and Red Rivers
29 Floating factory for production of gabions
30 Upstream morphological development threatening Chandpur town protection, Bangladesh
31 Measuring vessel equipped with echo-sounding, GPS and data storage with pc
32 Decision diagram for corrective and preventive maintenance (Source: van Noortwijk et al,
1996)
33 Possible effect of planform correction measures

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Preface

In 2002 the Department of Dike Management and Flood Control (DDMFC) of the Ministry of
Agriculture and Rural Development (MARD) requested the Rijkswaterstaat (Dutch Public
Works Dpt.) to review the problem of bank erosion in Vietnam and to assist in the preparation of
a plan for tackling this problem. The mission took place in the period 23 November-6 December
2003.

The goal of the mission was to get a more or less reprentative picture of these bank erosion
problems and to give recommendations on how in the future to tackle problems, and it was
certainly not intended to prepare a professional consultancy report on the bank erosion problems
in Vietnam. The mission spent one week in the Mekong Delta and 4 days in the Red River area.
Due to the limited time it was not possible to make a full inventory of problems on bank erosion
in Vietnam. Therefore, to get a general (and hopely representative) picture of the problem it was
decided to visit a number of representative sites in the upper part of Mekong Delta (non-tidal
area) and in the lower part of the Red River area. Special attention and time was allocated for
discussion with persons working for a long time in the visited areas (praciticians) or doing
studies for these areas (researchers). The guides from Dike Deparment (DDMFC) provided
useful information on legal, organizational and planning aspects.

The direct findings of the mission members are reported in this report. Apart from common
observations, observations are given using the disciplinary expertise of the different Mission
members (hydrodynamic, morphology, erosion, geotechnics, bank protection).

The mission likes to stress that such a short visit can not give the full overview of the erosional
problems in Vietnam (and hence it cannot replace a more fundamental study on this problem).
However, the work of the Mission and this report can be considered as a second opinion on this
problem provided by an independent group from abroad. It has provided the opportunity to
confront the actual Vietnamese approach to this problem with some foreign
approaches/expertise, and has made it possible to draw some conclusions and recommendations
in this respect. The mission hopes that their findings will be of use for further improvements of
the Vietnamese approach.

The results of this mission, conform to its terms of reference, are presented in this report. It
should be stressed that it was a challenging task, which would have been impossible to realize
without the close cooperation with Vietnamese experts and counterpart staff. A list of all
contacts in Vietnam is given as Appendix 2. We wish to express our deep appreciation for the
friendship and dedication of all mentioned persons who were involved in this complex effort.

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