Effects of climate change on water resources in the mekong delta, vietnam

Actual status of economic sectors I.2.3 Particular conditions of Mekong delta flooded areas I.2.3.1 Areas directly stricken by flood I.2.3.2 Impact of flooding on water supply and envi

P H D THESIS

EFFECTS OF CLIMATE CHANGE

ON WATER RESOURCES IN THE MEKONG DELTA,

VIETNAM

Author: Nguyen Thuy Lan Chi Supervisor: Prof Miroslav Kyncl

Ostrava, April 2018

Abstract

The Mekong Delta is located at the end of the Mekong River downstream, right before the river discharges itself into the East Sea and partly into the Gulf of Thailand This is a low and flat land, with an average elevation of 1-2 m above sea level and deposited by the silt of the Mekong River The Inter-governmental Panel on Climate Change, by analyzing and predicting the impacts of the rise of sea level, has recognized three deltas

to be classified as extremely endangered due to climate change: (1) the Mekong River downstream areas (Vietnam); (2) the Ganges - Brahmaputra River (Bangladesh); and (3) the Nile (Egypt) The World Bank study also shows that Vietnam is among the top 5 countries most affected by climate change In Vietnam, the two flatlands of Red River Delta and Mekong Delta are most affected If the sea level rises by 1 m, it is estimated that 5.3% of natural area, 10.8% of population, 10.2% of GDP, 10.9% of urban area, 7.2% of agricultural area and 28.9% of low land area there will be affected Risks in the Mekong Delta, including droughts and floods, will increase with heavy rains and prolonged droughts

During recent decades, Mekong Delta has been suffering from pretty clear impacts from the climate change The fluctuation of the weather factors and sea level rise have been causing negative impacts such as abnormal, big and small flood for different years; many stronger storms; more serious droughts; forest fire, river bank erosion, whirls, more and more dangerous tidal waves The traditional solutions for environmental adaptation have not been appropriate with the climate change in the Mekong Delta

As the coastal delta located at the lower part of a system of rivers which has big valley (Mekong River) and is vulnerable to the climate change, Mekong Delta is evaluated as suffering from most of main consequences of the climate change, namely:

- The consequences of the sea level rise from the sea side are big waves along with the coast, big flows in rivers and the river mouths, reduced land due to inundation and saltwater intrusion to the inland

consequence is the flood and drought Abnormal change of the rain in combination with the socio-economic activities in the valley, especially in the countries at the upper part of the rivers shall cause serious impacts to the water resources of the Mekong Delta region The double pressure of the climate change may cause to reduce or totally lose innate advantages on the land/water resources and the natural ecosystem of the Mekong Delta The risks of water shortage for daily activities/farming, loss of building land/shortage of farming land together with environmental catastrophes and biodiversity loss may cause strong impacts to both urban and rural areas of the Mekong Delta Inundation of the urban area causes to downgrade and quickly damage the urban and industrial, traffic and energy infrastructures In the rural area, some living land may be lost; the local traditional livelihood practices may be threatened The final consequences are leading to compulsory immigration/resettlement due to the environmental catastrophe

This study focuses on the following issues:

1 Identify the impacts of the climate change to the change of the water resource in Mekong Delta

2 Identify the possibilities of ensuring the water resource to the sustainable development of Mekong Delta

3 Predicted main issues in the Mekong Delta; Orientation for management and use

of water resources in the Mekong Delta;

4 Propose appropriate solutions to adapt the climate change for appropriate exploitation and use of the water resource in Mekong Delta Selection of pollution mitigation & treatment models appropriate to specific conditions in Mekong Delta flooded areas

In addition, I would like to thank the organizers, professors and secretaries of the sandwich program for allowing me to participate in the international network Especially,

I would like to give special thanks to and Dr Phan Dao for his advice and support while

I studied in Vietnam and Czech Republic

I would like to thank Ton Duc Thang University for their supporting me on during

research time

I would like to thank to my colleagues Dr Pham Anh Duc, Dr Nguyen Thi Mai Linh

They gave me much helpful advice and support on doing research during the past four years

I would like to thank Assoc Prof Phung Chi Sy, Dr Hoang Khanh Hoa for their

support me to design and implement research programs, applying research models in residential clusters in the Mekong Delta models

I would like to thank all members of the committees of my state examination and thesis, for their insightful comments

Finally, I sincerely thank my family who encouraged and motivated me and created favorable conditions during my PhD study

List of Abbreviations

o ADB: Asian Development Bank

o APHA: American Public Health Asociation

o CC: Climate change

o MD: Mekong Delta

o MRD: Mekong River Delta

o MONRE: Ministry of Natural Resources and Environment

o UN: United Nation

Chapter I

OVERVIEW I.1 Overview on Climate change

I.1.1 Change of global climate

I.1.2 Climate change in Vietnam

I.1.3 Climate change in the Mekong Delta

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1

2

3

I.2 Overview on the Mekong Delta

I.2.1 Natural characteristics

I.2.1.1 Geographical location

I.2.1.2 Climate characteristics

I.2.1.3 Hydrographic – Oceanic characteristics

I.2.2 Actual status of socio-economic development

I.2.2.1 Shifting of economic structures:

I.2.2.2 Actual status of economic sectors

I.2.3 Particular conditions of Mekong delta flooded areas

I.2.3.1 Areas directly stricken by flood

I.2.3.2 Impact of flooding on water supply and environmental sanitation

solutions

I.2.3.3 Characteristics of population, housing quality in flooded areas

I.2.3.4 Characteristics of water quality in flooded areas of MRD

I.2.3.5 Water using habits of people in MRD

CHANGES OF METEOROLOGICAL AND HYDROLOGICAL

FACTORS IN THE MEKONG DELTA IN RECENT YEARS

II.1 Meteorological and hydrological characteristics of MRD

II.2 Changes of meteorological and hydrological regimes

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19

II.2.2 Water volume discharged from China into the Mekong basin

II.2.3 Flows on the Mekong river mainstream

II.2.4 Flow from Tonle Sap Lake (Tonle Sap)

II.2.5 Water level at Tan Chau station

II.3 Progress of flow in the MRD

ACTUAL STATUS OF WATER RESOURCES AND

USE OF CLEAN WATER IN THE MEKONG DELTA

III.1 Actual status of water resources

III.2 Actual status of clean water supply in urban & rural areas

III.2.1 Sources of water and their quality

III.2.1.1 Rain water

III.2.1.2 Surface water

III.2.1.3 Groundwater

III.2.2 Actual status of water supply system in the Mekong River Delta

III.2.2.1 Actual status of water supply in urban areas

III.2.2.2 Actual status of water supply in rural areas

IV.1 The role of water resources in the economic development in MRD

IV.2 Impacts of climate change on water resources and flooding

IV.2.1 Risk of shortage of water sources

IV.2.1 Risk of shortage of water sources

IV.2.2 Change of surface water quality

IV.2.3 Increase of flood and land subsidence situation

IV.2.4 Tendency of increase of temperature

IV.2.6 Phenomenon of saltwater intrusion 40

Chapter V

SOLUTIONS FOR ADAPTATION TO CLIMATE CHANGE

ON WATER RESOURCES IN THE MEKONG DELTA, VIETNAM

V.1 Predicted main issues in the Mekong Delta

V.1.1 Increased inundation

V.1.2 Accretion and erosion

V.1.3 Drought and salinisation

V.2 Trend of water resources in the Mekong Delta in recent time

V.3 Management and use of water resources in the Mekong Delta

V.4 Development of the MDa based on water management and use

V.5 Solutions for adaptation to Climate change serving for the

reasonable exploitation and use of water resources in the Mekong Delta

V.5.1 Method for assessing the impacts of Climate change and building

solutions to adapt to Climate change in the Mekong Delta

V.5.1.1 Method for assessing the impact of Climate change

V.5.1.2 Methods for developing measures for adaptation to Climate change

V.5.2 Solutions for adaptation to Climate Change for the Mekong Delta

V.5.2.1 Overall solution for the whole Mekong Delta

V.5.2.2 Solutions in the field of agriculture

V.5.2.3 Solutions for Management of water resources

ENVIRONMENTAL POLLUTION MITIGATION & TREATMENT

MODELS AT RESIDENTIAL CLUSTERS IN FLOODED AREAS,

MEKONG DELTA VI.1 Selection of pollution mitigation & treatment models appropriate 60

VI.1.1 Clean water supply model

VI.1.1.1 Selection of water sources

VI.1.1.2 General viewpoint in recommendation of water supply model for

people in flooded areas

VI.1.2 Solutions for treatment of waste water

VI.1.2.1 Model of newly innovated septic tank

VI.1.2.2 Model of Biogas tank made of soft rubber bags to treat wastewater

and dungs

VI.1.3 Model of hygienic toilet

VI.1.3.1 Ecological toilet model

VI.1.3.2 Model of toilet using soft rubber bag

VI.1.4 Solutions for collection and treatment of solid waste

VI.1.4.1 Collection method

VI.1.4.2 Treatment plans

VI.1.4.3 Advantageous conditions in applying “Worm composting” method

VI.2 General description of the environmental status and activities in

Gao Long Den residential cluster, a site selected for implementing the

pilot model

VI.2.1 General overview

VI.2.2 Actual status of environment quality at residential cluster

VI.2.2.1 Quality of surface water sources

VI.2.2.2 Quality of water sources obtained from the pipeline route of Tam

Nong rural district Water Supply Station

VI.2.2.3 Problem of Waste water treatment

VI.2.2.4 Problem of solid waste management

VI.2.2.5 Quality of air environment

VI.2.2.6 The problem of using hygienic toilet

at residential cluster

VI.3.1 Overview about current clean water supply and environmental

sanitary conditions at the Gao Long Den residential cluster

VI.3.2 New model of water supply and sanitation in Gao Long Den

residential cluster

VI.3.2.1 Model of water supply

VI.3.2.2 Model of handling waste water

VI.3.2.3 Model of sanitary toilet

VI.3.2.4 Model of handling garbage

VI.3.3 Conclusion about results of pollution mitigation and treatment

models at residential cluster

List of Figures

o Figure 1.1 Map of flooding in 2000

o Figure 2.1 Monthly average rainfall in MRD downstream areas

o Figure 2.2 Qaverage in flood season in Chieng Sean

o Figure 2.3 Qaverage in flood season in Chieng Sean

o Figure 2.4 Qaverage in dry season at Kratie station

o Figure 2.5 Flow process at Prek Dam station

o Figure 2.6 The water level at Tan Chau station

o Figure 3.1 Map of average of annual rainfall in the Mekong Delta

o Figure 3.2 Map of partition of surface water quality in MRD region

o Figure 3.3 Map of partition of groundwater areas and groundwater reserves

o Figure 3.4 Map of actual status of water supply in MRD

o Figure 3.5 Drilled wells and rainwater trough for daily use in rural areas

o Figure 4.1 Effects of flooding in the Mekong Delta

o Figure 6.1 Sketchy description of operation of 5-compartment Septic tank

o Figure 6.2 Perspective outline of a type of VinaSanres toilet

o Figure 6.3 A toilet on ditch – a common type in rural areas in Mekong delta

o Figure 6.4 A part of a toilet cum bathroom – Gao Long Den resettlement area

o Figure 6.5 A garbage dump is flooded

o Figure 6.6 A local person takes water for daily use

o Figure 6.7 Structure of the container handling daily garbage by worms

List of Tables

o Table 1.1 Population, population density in flooded areas in the Mekong Delta

o Table 1.2 Urban population and rate of urbanization in flooded areas

o Table 1.3 Number of residential houses in flooded areas in the Mekong Delta

o Table 1.4 Housing and housing density in flooded areas in the Mekong Delta

o Table 6.1 Quality of surface water source in Gao Long Den Residential Cluster

o Table 6.2 Quality of water supplied at the concentrated Water Supply Station of Tam Nong rural district

o Table 6.3 Results of measurement of air environment quality at Gao Long Den residential cluster

o Table 6.4 Microclimate factors and noise level

o Table 6.5 Analysis result of input and output water The analysis result of input and output water samples after being handled by biogas bag

Chapter 1

OVERVIEW

I.1 Overview on Climate change

I.1.1 Change of global climate

According to the IPCC (2007) - (Inter-governmental Panel on Climate Change) [14], Climate change (CC) is a change in the state of the climate system, which can be perceived by the change in the average and fluctuation level of its attributes that is maintained for a sufficient period of time, typically for decades or even longer In other words, if we consider the equilibrium of a climate system as an average weather condition including its fluctuations in several decades or longer, then CC is a shift from a certain state of equilibrium to other one of the climate system CC is characterized by global warming, rise of sea level, increase of natural disasters and extreme climatic phenomena The occurrence of Climate change may be due to two causes: natural processes and human effects

Most scientists have asserted that human activities have been the cause of the change of global climate The main cause of this change is the increase in concentration of greenhouse gases leading to the increase of greenhouse effects, of which the generation

of CO2 from the use of energy from fossil fuel is of high importance

According to the Fourth Assessment of the Inter-governmental Panel on Climate Change (IPCC, 2007), the major expressions of global climate change are specifically as follows[14]:

- The global average temperature has increased by 0.74°C during the period

between 1906-2005, the temperature increase rate in the last 50 years is nearly double in comparison to the previous 50 years

- Rain precipitation tends to increase towards 30ºN latitude, but tends to decrease

significantly in tropical areas In recent times, there have been signs showing the increase of heavy rainfall phenomenon

- The global average sea level has increased at an average rate of 1.8mm/year

during the period of 1961-2003 and at a rate of 3.1mm/year between 1993-2003

In recent years, the total increase of sea level is 0.31m (± 0.07m)

- Drought occurs more often in tropic and subtropic areas, the main causes of which

are the reduction of rainfall and the rise of temperature leading to the increase of evaporation

Thus CC has been occurring on a global scale, which expressions may be different between regions, but some common characteristics can be concluded such as: rise of temperature, vigorous fluctuation of rainfall and signs of rainfall increase in rainy seasons, rainfall decrease in drier seasons, increase of heavy rain phenomenon, more occurrence of droughts, more complicated operation of storms and tropical low pressures, more frequent occurrence of El Niño phenomenon with violent fluctuation

I.1.2 Climate change in Vietnam

In recent times in Vietnam, the development of climate also has similarities to the world’s general situation CC has affected all regions, areas and fields including natural resources, environment and socio-economy, of which water resources, agriculture and rural development, health and the coastal areas will be affected the most

The impact of CC on water resources in Vietnam is considered to be extremely serious and Vietnam is classified as water deficit group of countries (statistic figure per capita is 4,400 m3/person/year compared to the world average of 7,400 m3/person/year) The deterioration of water resources is increasing in both quantity and quality due to the increasing demand for water, the indiscriminate exploitation and use of water, the lack of planning and especially the alert declination of rainforests [38] Under the impact of CC, as the average temperature rises, the increase of abnormalities of weather, climate and natural disasters will significantly affect freshwater resources regarding the following aspects:

- The demand for water for daily use, water for agricultural or industrial production,

etc are all increasing Besides, the level of water evaporation of water bodies

(ponds, rivers, streams ) is also increased The consequence is the degradation of water resources both in quantity and quality

- Changes in rainfall will lead to changes in the flow of rivers and the intensity of

floods The thaw of snow covering the poles and the tops of high mountains will speed up the flow of rivers and increase the number of floods When the ice on mountains depletes, the number of floods will reduce but the streams will also decrease or even deplete Water shortage will be more serious This is very characteristic of Asian countries which sources of river water depend heavily on upstream water

I.1.3 Climate change in the Mekong Delta

The Mekong Delta is located at the end of the Mekong River downstream, right before the river discharges itself into the East Sea and partly into the Gulf of Thailand This is a low and flat land, with an average elevation of 1-2 m above sea level and deposited by the silt of the Mekong River [31] The Inter-governmental Panel on Climate Change, by analyzing and predicting the impacts of the rise of sea level, has recognized three deltas

to be classified as extremely endangered due to climate change: (1) the Mekong River downstream areas (Vietnam); (2) the Ganges - Brahmaputra River (Bangladesh); and (3) the Nile (Egypt) The World Bank study also shows that Vietnam is among the top 5 countries most affected by climate change In Vietnam, the two flatlands of Red River Delta and Mekong Delta are most affected If the sea level rises by 1 m, it is estimated that 5.3% of natural area, 10.8% of population, 10.2% of GDP, 10.9% of urban area, 7.2% of agricultural area and 28.9% of low land area there will be affected Risks in the Mekong Delta, including droughts and floods, will increase with heavy rains and prolonged droughts Since 2009, the START Center in Southeast Asia (Chulalongkorn University, Thailand) and the Climate Change Research Institute (Can Tho University, Vietnam) have coordinated to commission the PRECIS climate model with A2 and B2 scenarios, based on a series of climate data in the period of 1980-2000, to make

prediction for the period of 2030-2040 The results of the model show that many areas of the Mekong Delta will incur the following effects [30]:

- The highest average temperature during dry season will increase from 33-350C to 35-370C;

- Rainfall at the beginning of summer-autumn crop (April 15th - May 15th) will decrease by 10-20%;

- Monthly distribution of rainfall will have the tendency to decrease at the beginning

and the middle of summer but slightly increase at the end of rainy season;

- Total annual rainfall in An Giang, Can Tho and Soc Trang will reduce by 20%,

and the rainy season will start about 2 weeks later than normal

In general, the development of climate at present and in the future are unfavorable to the production, means of subsistence and life of the Mekong Delta dwellers The impacts of

CC can restrain local socio-economic development plans As the terrain is located at the end of downstream area, the entire flooding flows from the upper reaches discharged to the Mekong Delta through the two tributaries of Upper river and Lower river and the inland overflow will cross the Cambodian and Vietnamese border to flood many lowland areas, mainly the Long Xuyen Quadrangle - Ha Tien, Dong Thap Muoi and the lowland between the two tributaries of Upper river and Lower river

Thus, the impact of CC on the Mekong Delta is huge, according to the latest scenarios of rise of sea level which have been announced: if the sea level rises from 73cm - 100cm in

2100 (the end of the 21st century), there will be 39% of land area being flooded, 35% of the population will be adversely affected by complicated weather, which is more and more extreme and out of normal rules [30]

I.2 Overview on the Mekong Delta

I.2.1 Natural characteristics

I.2.1.1 Geographical location

The Mekong Delta encompasses an area of 93,781km2, ranking the third in the world's 34 largest deltas (after the Amazon delta with an area of 467,707 km2 and the Ganges delta

with an area of 105,641 km2), represented 12% of the country's total area and includes 13 provinces: Long An, Tien Giang, Dong Thap, Ben Tre, Vinh Long, Tra Vinh, Can Tho, Soc Trang, Ca Mau, Bac Lieu, An Giang, Kien Giang and Hau Giang The Mekong Delta

is the downstream and coastal part of the Mekong River It is the tenth largest river in the world with a basin originated in Tibet at an altitude of 5,000 m and a total area of 795,000 km2, with a length of 4,200 km, flowing through six countries including China, Laos, Thailand, Myanmar, Cambodia and Vietnam The area of the Mekong river delta is 49.367 km2, including parts from China, Myanmar, parts of Thailand, entire Laos, Cambodia and one fifth of Vietnam The so-called Mekong River Lower Basin starts at the Golden Triangle between Thailand, Laos and Myanmar at an altitude of 500 m and represented 77% of the total Mekong river basin [32]

The Mekong Delta is frequently and strongly affected by two large bodies of water which are the river water discharged from the Mekong river upper reaches and the sea tides The particularities in climate, distribution of flows combined with the topography have profoundly influenced the process of formation of customs and habits in production, life, daily activities and flood preventing and combating measures of Mekong Delta people The Mekong Delta flood area is about 1.6 million ha (40% of the area) Flooded areas cover 60 districts (out of a total of 99 districts) in 9 provinces (out of a total of 13 provinces in the Mekong Delta): Long An, Dong Thap, Kien Giang, An Giang, Can Tho, Hau Giang, Vinh Long, Tien Giang, Ben tre Of which the four provinces most severely affected are Long An, Dong Thap, Kien Giang and An Giang [32]

I.2.1.2 Climate characteristics

(1) Air temperature: High temperature background which is relatively uniform The

average annual temperature is about 26.4 ÷ 27.3oC The total annual temperature is up to 9,500 ÷ 10,000oC The difference between the average temperature of the hottest month and the coldest month is 3 ÷ 4oC The fluctuation between daytime and night temperature

is 7 ÷ 8oC

(2) Sunshine and solar radiation: Solar radiation in the Mekong Delta is relatively stable

and abundant during the day, with abundant sunshine (average hours of sunshine is 7.2 hours/day), high radiation energy (total of average radiation level is 150.8 Kcal/

cm2/year)

(4) Rainfall: Rainfall in the Mekong Delta fluctuates greatly in space and time The

annual rainfall reaches 1,600-3,000 mm The average monthly rainfall is fairly distributed throughout the rainy season at 200-300 mm/ month with 15-20 rainy days per month An approximate 90% of annual precipitation is concentrated in the months of rainy season (from May to November) In the months of rainy season, the rainfall is relatively even, particularly in October and November the rainfall is relatively high at about 600mm The dry season months (from December to April of subsequent year) has the average rainfall

at about 50 mm

(5) Wind regime: Due to its flat terrain, the whole Mekong Delta region has the same

wind regime The wind changes its direction obviously per season and its prevalent direction coincides with the monsoon direction of the whole region The average annual

wind speed ranges from 3.0-3.9 m/s

(6) Thunderstorms: Often occur in the period from April to September depending on the

area Rach Gia area (Kien Giang) has the highest number of thunderstorm days in a year with the annual average thunderstorm days being 60 days, the number is 50 days in Soc Trang, 20 days in Phu Quoc, 10 days in Ca Mau In December, January, February there is

almost no thunderstorm occurrence

I.2.1.3 Hydrographic – Oceanic characteristics

(1) River system in Mekong Delta

The length of the main rivers is 230 km The network of rivers and canals between main streams consists of important rivers such as: Cai Lon, Ong Doc, Bay Hap, Cua Lon and Ghenh Hao A dense small canal system linking the rivers together has a total length of 4,900 km The river density of the whole area is 4 km/km2 The distribution of river water between the Upper and Lower rivers changes in river sections due to tidal influence The

river water regime in MRD is divided into two distinct seasons: the flood season and the dry season Due to the regulation of the Tonle Sap, floods in MRD occur later than in the middle and upper reaches The flood season usually lasts for 5-6 months, from July to November, December Flood water rises slowly and the flood peak often occurs in September, October each year The flow in flood season accounts for 70-80% of the annual flow, in particular the three months with largest flows accounting for about 59%

of the total annual flow [39]

I.2.2 Actual status of socio-economic development

I.2.2.1 Shifting of economic structures

The economic structure of the Region has recently shifted towards increasing the proportion of industry and services while gradually reducing the share of agricultural sector by 38.5% - 34.7% - 26.6%, respectively

I.2.2.2 Actual status of economic sectors

(1) Industry - small industry and handicraft: The industrial production value increased

annually by 16.6% on average in the period of 2010-2015 The rapid development of industrial production has given rise to the development of other economic sectors

(2) Trade and services: are developed mainly in cities, towns, townships, surroundings of

traffic roads and Industrial Zones, the sectors with strongest increases are post and telecommunication, banking, warehouses and transportation, etc and serve the industrial

development and speed up the urbanization process (total export volume in 2015 increased by 2 times compared to 2010)

(3) Agriculture: is shifting towards regional and sectoral planning and keeping areas for

rice plant, aqua-products development zones, special and clean fruit orchards together with conversion of the purpose of use of agricultural land into effective and special purpose land Rice export represents 90% of the country’s capacity, significantly contributing to the National food security

I.2.3 Particular conditions of Mekong delta flooded areas

I.2.3.1 Areas directly stricken by flood

The flood directly-stricken region in the MRD encompasses an area of about 1,867,270 hectares, accounting for 47% of the Mekong Delta's natural area and 80% of the natural area of the nine flood-affected provinces of Dong Thap, Long An, An Giang, Kien Giang, Can Tho, Hau Giang, Vinh Long, Tien Giang, Ben Tre This region is enclosed in an area

as follows [41]:

- To the North is Vietnam - Cambodia border, which spreads for about 313km from

Ha Tien (Kien Giang) until Duc Hue (Long An)

- The South side is bounded by Giao Hoa - Chet Say canal (Ben Tre); Mang Thit

canal (Vinh Long) and Xeo Chit canal (Can Tho)

- To the West is Cai Lon canal - Rach Gia canal - Ha Tien

- To the East is Vam Co Dong river - Thu Thua canal

Based on its flooding features, MRD can be divided into 4 following particular areas [41]:

- Deep flooded area > 3 m: An area of 2,641 km2, representing 13.5% of the total flooded area, belonged to 4 districts of Dong Thap which are Tan Hong, Hong Ngu, Tam Nong, Thanh Binh and 5 rural districts and townships of An Giang which are Chau Doc, An Phu, Tan Chau, Phu Tan and Chau Phu townships This

is the upstream head area and is the main flow from Cambodia that causes floods

in MRD

- Deep flooded area 2 ÷ 3 m: covering an area of about 3,145.6 km2, accounting for 16.1% of the flooded area in 3 districts of An Giang (Cho Moi, Chau Thanh and Thoai Son), one district of Dong Thap and 2 districts of Long An (Vinh Hung and Moc Hoa)

- Flooded area 1 ÷ 2 m: An area of 7,482.5 km2 accounting for 38.3% of the flooded area Most of this area is located in the floodplain area in 6 provinces: Long An, Tien Giang, Dong Thap, An Giang, Can Tho and Kien Giang

- Flooded area under 1 m: An area about 6,487 km2, accounting for 34% of the total area, including the rest of the Southern part of the flooded area

The largest flood depth partition map in the Mekong Delta during the 2000 flood is

shown in Figure 1.1

The course of a flood in the Mekong Delta usually goes through three stages: The first

stage may be called river flood: The water discharged from the upstream of the Mekong

River quickly rises the water level of the Upper and Lower rivers and then following the Hong Ngu and An Binh canals and local canals to flow into the DTM and Vam Co Tay

river The middle stage called the overflowing flood: Starts when the water level in Tan

Chau is as high as 2.8 - 3.0 m, the water then flows into the main canals but certain quantity of water also starting to overflow the Upper river banks and pouring into DTM

creating a process of surface overflowing The last stage is the flood withdrawal stage: in

this stage, floods generally withdraw towards the Upper river (at ratio of 55-57%) and Vam Co river (at ratio of 30-32%)

Figure 1.1 - Map of flooding in 2000 [41]

I.2.3.2 Impact of flooding on water supply and environmental sanitation solutions

(1) Water supply solution

Most of the people in the flooded area use surface water as their water supply, therefore the quality of surface water greatly affects the supply of clean water during the flood season The two biggest impacts of flooding are the aluming of surface water and the washout of pollutants that degrade water quality [40]

- Fluctuations in annual flood regimes affect the distribution of sour waters in the

area In DTM, in the years where strong flooding appeared, sour water was quickly pushed to the downstream areas of the two Vam Co rivers, while in the years of weak flooding the tide of June shifted the sour-water-adjacent-area until the area nearby South Moc Hoa In general, sour water areas account for about 57% of DTM area, in which the sour areas which last for about 4 months representing 16% In Long Xuyen Quadrangle area, the sour water period lasts longer than in DTM area

- The increase of amount of silt in the surface water during flood season has made

the use of surface water even more limited The water in the area between the two rivers in An Giang province and in the West of the Lower river has a high content

of silt, while Long Xuyen Quadrangle and DTM area has smaller content of silt, but due to mixing with the flood water overflowing the border, the contamination level is higher

- The situation of surface water pollution in deep flooded areas is often more severe

than in shallow flooded areas both in terms of time and level

- Since the quality of surface water varies over time and per area depending on the

annual flood regime, the selection and application of surface water treatment technology is very difficult

(2) Solutions for Environmental Sanitation

Flooding regimes and flooding levels exert a great impact on environmental sanitation conditions, especially in concentrated residential areas, of which the most severe impacts are on the newly established residential clusters In deep flooded areas in An Giang, Dong Thap and Long An, there is a big number of newly established residential clusters, but the environmental sanitation infrastructure has not been properly invested and built It

is quite common that waste water drainage and treatment systems, solid waste landfills have either not been invested or just temporarily invested/ built Actually, it is very

difficult to find feasible solutions for treating manure, draining waste-water and managing solid waste for residential clusters

I.2.3.3 Characteristics of population, housing quality in flooded areas

(1) Characteristics of population in MRD

According to statistics in 2015, there are about 8,855,937 people in flooded areas, accounting for 55% of the population in MRD The average population density in flooded areas is about 490 people/km2 This density is 1.2 times higher than the average population density of the whole MRD This shows that floodplain generates more jobs and settlement than other areas Compared to the whole country, this average population density is 2.2 times higher than the national average density

Table 1.1 - Population, population density in flooded areas in the Mekong Delta [28]

No Flooding level Population

(person)

Ratio (%)

Population density (person/km2)

long and frequent floods during the years, this area still attracts people to come for their living, settlement and development

Table 1.2 - Urban population and rate of urbanization in flooded areas [28]

No Flooded areas Population

(person)

Urban population (person)

Ratio (%)

03 Shallow flooded < 1,5 m 5.825.958 1.169.326 20,07

(2) General characteristics of housing and housing quality

Table 1.3 - Number of residential houses in flooded areas in the Mekong Delta [28]

Table 1.4 - Housing and housing density in flooded areas in the Mekong Delta [28]

(house unit)

Housing density (house/km2)

Housing quality in flooded areas: Among the number of houses mentioned above, the

flooded areas have 65-70% temporary houses, which is nearly 3 times the national average (the average in the whole country is 25-26%)

I.2.3.4 Characteristics of water quality in flooded areas of MRD

(1) Rainwater: has good quality and is stored and used directly as water supply

However, the collection and storage system is usually not well-cleaned in terms of hygiene, not having a system for discharging first-dropping rainwater and a pre-filtering system, thus quality is partly reduced through the storage process On the other hand, as rain is only concentrated in the six months of the rainy season, the storage of rainwater for use in dry season is a very difficult problem for poor rural areas in MRD

(2) Surface water: Sources of surface water are plentiful but the quality varies from

region to region and depends on the annual flooding condition In Long Xuyen Quadrangle and DTM areas, the surface water is affected by alum due to the soil characteristics and the washout regime of the flood water In addition, these areas receive flood waters overflowing across the border that increases the level of contamination from various pollutants and makes the application of surface water treatment technology very difficult (the quality of input water is unstable leading to frequent changes of operating parameters: chemical, reaction time, deposition and filtration process, etc.) Water in the area between the two rivers has better quality but higher silt content during the flood season, leading to higher processing costs during the flood season Water in the West area

of the Lower River has similar quality after construction of the works to drain water to the West Sea which prevents the aluming flood flow from the Long Xuyen Quadrangle However, the flood overflowing large urban areas in flooded areas leading to high level

of contamination with organic matters and micro-organisms Surface water treatment technology for this area is often more complicated and expensive

(3) Groundwater: In two large flooded areas which are Long Xuyen Quadrangle and

DTM, groundwater is often affected by heavy aluming or saltwater intrusion (due to hydro-geological characteristics thereof) Expensive and energy-intensive desalination technology is very difficult to apply to rural areas While simple de-ironing/ iron-reduction technology is commonly used on a medium scale As for the wells in households, it is difficult to apply the above technology due to economic inefficiency and the fact that people are difficult to operate the treatment process themselves

I.2.3.5 Water using habits of people in MRD

Most of the population in MRD in general and in flooded areas in particular live in rural areas with different population densities A common feature of the distribution of rural population is that people live along the banks of canals and along traffic roads, or they have the road in front and the river behind their houses Due to the fact that the terrain is crisscrossed with rivers and canals and often affected by prolonged floods together with a low-density population, we can say that the rural infrastructure conditions are very weak and difficult to develop in a short term It is the natural conditions, the living standards, the intellectual levels and the rural population distribution characteristics that have profoundly influenced the formation of customs and habits in daily activities in rural areas, of which the habits of using water for daily activities and environmental sanitation are among the oldest ones and thus are difficult to change Depending on the natural conditions and economic conditions, MRD rural areas in general and its flooded areas in particular have a number of water using practices as follows:

(1) Using rainwater: People collect rainwater and store it in water jars, tanks or

reservoirs for preparing food, drinking, doing the laundry and for other daily use

purposes The volume of rainwater containers depends on the economic condition of each household This habit is the most common in all rural areas of the country Of course, rainwater used for daily activities becomes extremely scarce in the dry season, especially

in the years where the rainy season comes late, or even in the case of prolonged drought

in the dry season As a thrifty practice, people used to reserve rainwater for cooking or drinking in the dry season, and must use other sources of water for bathing, washing, etc

(2) Using river water for daily use purposes This practice is very common in MRD,

especially in areas where residents live along the banks of canals In the dry season, when the reserve of rainwater becomes exhausted, people often practise the habit of using river water for bathing, washing, doing the laundry and cleaning the pigsties and sheds regardless of the water quality, except the case when the river water is too salty to be used Poor rural environmental sanitation and the increasing use of pesticides in agriculture have greatly impacted the use of river water for daily activities and are the causes of many diseases, particularly the intestinal diseases and gynecological diseases in women

(3) Using water in ponds, lakes for daily activities This habit is often associated with the

distribution of population along rural traffic roads where there are not rivers and canals nearby This type of water usage is very popular with single households living in the fields In fact, in many places in the Mekong Delta, the ponds and lakes in the villages or rice fields are still considered as the most economic means of rainwater reserve for daily activities of rural people Though there has been no statistics on the quantity and volume

of rainwater in ponds and lakes, the preliminary survey on water use for daily activities in rural areas in the Mekong Delta showed that rural people in many areas still maintain village ponds and ponds in their own houses to conserve rainwater for daily use, both in dry and rainy seasons Most of the village ponds have already existed from ancient times and thus have been eroded and deposited over time, and people in the village usually have to make a pool contribution to renovate them at the end of the dry season each year The quality of pond water depends on the land and the habits of people living there

Water often has fairly good quality, low turbidity and is not salty even in some coastal areas However, in some areas where there are practices of free-riding animals in the field; duckling, raising fish in reserve ponds, bathing or doing laundry right in the lakes the water sources may be contaminated

Chapter 2

CHANGES OF METEOROLOGICAL AND HYDROLOGICAL FACTORS IN

THE MEKONG DELTA IN RECENT YEARS

II.1 Meteorological and hydrological characteristics of MRD

The river water regime in the coastal plain is dominated by the tides of the East Sea and the Gulf of Thailand, with corresponding tidal regimes as ununiform semi-diurnal tides and ununiform diurnal tides These two types of tides with different modes penetrate into rivers and canals and create a very complicated picture of tides However, the East Sea tides prevail those penetrating from the Gulf of Thailand

The average annual flow of the Mekong River through Kratié (Cambodia) is about 13,500 m3/s, corresponding to a total flow (W) of up to 430 billion m3/year When it joins Tonle Sap river, the average flow increases to 13,644 m3/s and begins to penetrate into Vietnam territory by two ways - Tan Chau and Chau Doc The average flow in Tan Chau

is 11,000 m3/s (accounting for 80% W), while in Chau Doc is 2,650 m3/s (20% W) This difference is due to the riverbed and regional terrain The water level of the Mekong river

at Tan Chau is higher than at Chau Doc Most of the water volume flows to the East Sea, with an average flow of up to 15,854 m3/s (approx W = 500 billion m3/year), the remaining of about 5% - 10% follows rivers and canals and discharges into the Gulf of Thailand, among them are Tri Ton, Ba The, Cai San, O Mon, Thot Not canals and a new canal which runs through Long Xuyen Quadrangle - Ha Tien region [47]

From the end of 2015 until present, MRD has been facing fierce dry seasons Saltwater intrusion appeared early and abnormally The results of observation in 12/2015 showed a salinity of 4g/liter, deep intrusion into the inner fields as far as 60-65 km, which has not ever happened in the past Droughts last for long time and drought areas in the coastal provinces of MRD are expected to be as muach as 35% of the total area From the end of 2/2016 until present, salinity level has remained high and maintained at an alarming rate

El Nino phenomenon, with its stronger intensity and higher level, lasts for a record period from 2014 to mid-2016 (longer than the El Nino in 1997-1998) Statistics from 2012-

2016 show that [47]:

- The temperature is higher than the average of previous years from 1-1.5oC, the rainfall is 30-50% lower than previous years

- The total flow of the Mekong River to MRD is insufficient in comparison with the

average flow of previous years; the upstream flow to the Mekong Delta is limited leading to droughts, and salt intrusion becomes more dangerous In addition, the flood tide phenomenon lasts until February and March leading to intrusion of saltwater deeply into estuaries, causing serious impacts to the region's water resources

II.2 Changes of meteorological and hydrological regimes in recent times

Based on the data of rain, water level, flows synchronously collected among stations from 1985 to present, we can see that: Droughts, and saltwater intrusion in dry season in MRD which happens early, intrudes deeply on a wide extent and in a long-term have been seriously affected the production and daily activities of people Analysis on meteorological and hydrological data in the Mekong river basin to better understand the hydrological situation, and indicate the irregularity and its impact on the Mekong River downstream areas [39]

II.2.1 Rainfall in the Mekong river downstream areas

In 2015 the rainy season comes late but ends early, the total rainfall on stations is less than the average of the previous years from 15-45% The average downstream rainfall of the Mekong basin during the year is about 1,300mm, 5% less than the previous year's average In the first two months of the flood season (May and June), the rainfall is 30-45% less than standard level In all months from August to December, the rainfall level is always lower than the average about 20%

Figure 2.1 - Monthly average rainfall in MRD downstream areas

(Blue – Average from previous years; Striped – in 2015) [44]

II.2.2 Water volume discharged from China into the Mekong basin

Taking the flow at Chieng Sean station, located on the border between China and Laos, for evaluation The results from 2009 until present show that: the volume of flow in flood season from China down to the Mekong basin reduced by about 25% from the average, particularly in 2015, the reduction is 32% This is a reflection of the regulation of reservoir system in China's territory which stores water during the flood season that cut down the downstream flood volume

Figure 2.2 - Qaverage in flood season in Chieng Sean

In the dry season of 2015-2016, the flow at Chieng Sean was rather low but still higher than in the typical 1998-1999 year of drought, roughly equal to the year of 1994-1995

Figure 2.3 - Qaverage in flood season in Chieng Sean

Qaverage in dry season in Chieng Sean [44]

II.2.3 Flows on the Mekong river mainstream

At Vientiane station, the average flow in November and December 2015 was about 30% lower than the average of previous years and approximately equal to the volume of the

1998 historical year of drought The source of water on the Mekong mainstream supplied

to the Mekong Delta is observed at the Kratie station

Figure 2.4 - Qaverage in dry season at Kratie station [44]

During the period from 11/2015 to 10 January 2016, the flow in Kratie is very low, reaching the lowest number in more than 30 years (according to the series of data from 1985-2015) The average Q of this period is less than the average value of the 1985-2016 series of data by about 40%

II.2.4 Flow from Tonle Sap Lake (Tonle Sap)

Taking the flow at the Prek Dam station which is the outlet of Tonle Sap Lake for analysis, we can draw out some key points [41]:

- Because the flow on the Mekong mainstream is too low, the time at which the

water flows from the main river back into the lake to store water for Tonle Sap Lake is 46-day later than the average, the entire time for supplying reserve water

to the lake is only 65 day, reducing nearly half of the average in the previous years Consequently, the volume of mainstream water supplying for the lake has dropped 33%

- The additional flow to the lake from Tonle Sap basin decreases sharply due to less

rain This resulted in a decrease of 53% in the water volume supplied to the Mekong Delta during the period from October 2015 to 22 February 2016 compared to the average in the same period of previous years Especially in the months from November 2015- February 2016, the flow decreased by 56%

- Compared with the most drought stricken year of 1998-1999 in the past, the

volume of water flowing back to the lake for reserve in 2015 is higher, but the total flow into MRD is instead lower than 23% This shows that the severity level

of drought in 2015 is by far greater than in 1998

Figure 2.5 - Flow process at Prek Dam station [41]

II.2.5 Water level at Tan Chau station

Taking the water level of Tan Chau station on the Upper River as representative of the Mekong river water level at the entrance to the Mekong Delta From the beginning of the dry season, the water level at Tan Chau station is unusually low From November 2015 to

30 January 2016, it reached the lowest record among the series of data under monitoring, which is lower than the average of many years by 0.9 meter, particularly in the first two months of the dry season (November and December) it is lower by about 1.2m

Figure 2.6 - The water level at Tan Chau station [41]

One feature to be noted is, the average Hmin value per day at the Tan Chau and Chau Doc stations has a downward trend, which means that tides have strong impact on the Mekong Delta and Qmin from the upstream to the Mekong Delta also has a downward trend The combination of the two factors leading to [the fact that] saltwater intrusion can

go deeper

In summary, the dry season of 2015-2016 occurs anomaly due to El Nino phenomenon with high intensity, at high level for long period The volume of water supplied to MRD from the upstream is severely insufficient right from the beginning of the dry season by a volume nearly 50% Consequently, saltwater intrusion came earlier and stronger than in the same previous period, the salinity level of 4g/liter appeared in January 2015 with influence extent as far as 40-60 km The subsequent months is the peak period of dry season, in which [water level] is expected to be lower than ever Therefore, drought, saltwater intrusion in the MRD is forecasted to be very serious

II.3 Progress of flow in the MRD

The analyses of flow progress in MRD are based on the data on measurement of flow rates collected by hydrological stations in MRD and the Kratie hydrological station, the flow progress in MRD in recent years is summarized and analyzed as follows: [49]

The dry season in the Mekong Delta downstream areas can be considered as from

December to June of the subsequent year However, in December the flow was still relatively high due to the prolonged effects of floods In June, due to effects of early rains

at the beginning of the season, the flow rate in the river has also increased obviously Thus the dry season period actually lasts from January to May

In the dry season, during the dryest period (March-April), tide has a major influence on

the hydrological regime in the Mekong Delta

- The reverse flow rate in Tan Chau can reach 3,750 m3/s and 6,780 m3/s in Chau Doc

- The lowest monthly average flow rate in recent years in Tan Chau and Chau Doc

is about 2,600 m3/s

- The average flow rate in dry season in the Mekong Delta tends to decrease, by an

annual average about 20 m3/s

During flood season:

- The highest monthly average flow rate in many previous years in Tan Chau is

18,640 m3/s (September) and in Chau Doc is 5,890 m3/s (October)

- Total average flow rate of the highest monthly average flow rates in many

previous years in Tan Chau and Chau Doc is about 24,530 m3/s

- The average flow rate in flood season in MRD tends to decrease, by an annual

average about 30 m3/s

The flow into the MRD is greatly affected by the upstream flow The Kratie hydrological station on the Mekong river mainstream and the PrekDam station on Tonle Sap river basin are two locations that control the gateway of flow into the Mekong Delta At the Kratie hydrological station, the average annual flow increased by 11 m3/s in the flood season, 17 m3/s in the dry season, 23 m3/s in the month where flow rate is lowest; the highest monthly average flow reduced by 15 m3/s per year

Chapter 3

ACTUAL STATUS OF WATER RESOURCES AND USE OF CLEAN WATER IN THE MEKONG DELTA

III.1 Actual status of water resources

Water resources is one of the important natural resources that determine the existence and development of MRD region Local people and authorities have been seeking ways to cope with water-related difficulties such as floods, droughts and saltwater intrusion by various means of construction and non-construction These efforts have made the Mekong Delta the largest agricultural production area in the country However, under the impact of water development in the upstream of the Mekong River together with the internal development of MRD and the change of global climate, the Mekong Delta's water resources have changed in unpredictable directions The change in water resources has had a significant impact on the socio-economic life of the locality [31] Results of the analysis of surface water quality in the Upper river, Lower river and major tributaries of

the Mekong river area are presented in the Appendix

Water quality in the major rivers changed markedly per season The content of dissolved substances in the dry season is higher than during the flood season The quality of flood water along the border is still good, not sour, with toxic content within the limit permitted; but since a large amount of silt has deposited on the delta area in Cambodia territory, then when the flood water overflowing the border into MRD, its content of silt

is very low, which did not exceed 200 g/m3 even in the highest month In flooded areas, the development of water quality is fairly complicated due to be subjected to factors such

as climate, hydrology and human activity The content of major dissolved substances such as Na, K, Ca 2+, Mg 2+, Fe 2+, Al 3+, SO4 2-, Cl -, HCO3 – varied per season, which is higher in dry season than in flood season However, MRD surface water is highly contaminated by micro-organisms with an average concentration of Coliform about