WATER RESOURCES IN THE MEKONG DELTA: A HISTORY OF MANAGEMENT, A FUTURE OF CHANGE pdf

Section 1 provides an historic outline of water resources and management in the Mekong River basin and the delta in particular.. It tracks the introduction of Integrated Water Resource M

WATER RESOURCES IN THE MEKONG DELTA: A HISTORY

OF MANAGEMENT, A FUTURE OF CHANGE

Dr To Van Truonga, Tarek Ketelsenb

Introduction

The Mekong Delta is characterized by change, which occur over a wide range of spatial

and temporal scales In the past the delta lay submerged below the sea and today it continues

to accumulate sediments from as far away as the Himalayas so that the delta is constantly

changing and reclaiming land from the sea In fact, because of the delta’s dependence on a

combination of ecosystem functions including tides, rainfall, and erosion that operate over a

short timeframe, it is highly susceptible to human and environmental change Now the Mekong

Delta, a fringing ecosystem between terrestrial and marine environments, is facing perhaps the

most devastating change of all, unique because Climate Change is bringing changes at a rate

unprecedented in recent history Whereas in the past change was a comparatively slow

phenomenon with patterns set in motion over thousands of years, current changes require a

sense of urgency as significant changes to the hydrologic regime are occurring over decades

and even years requiring water management initiatives that are flexible and capable of evolving

and adapting close to the speed at which climate change is occurring Change has therefore

become an issue because of the accelerated scale at which it is operating in both biophysical

and socio-economic environments

Regardless of what mitigation efforts are taken internationally, climate change impacts

for the next 40 years are inevitable (IPCC, 2007) After 2050, the impacts of climate change will

largely depend on how we, as an international community, respond today, but changes to sea

levels, rainfall regimes and storm frequencies before 2050 are determined by current levels of

CO2 in the atmosphere This means that for the vulnerable communities in the world,

adaptation is the most urgent issue Furthermore, most impacts of climate change will be

transferred to human and ecological communities via the hydrologic cycle, for example, through

sea level rise, storms, flooding, and droughts This places water resource management (WRM)

at the front lines of human adaptation to climate change A recent study by the World Bank

(2007) identified Viet Nam as the most vulnerable nation in the developing world in terms of

population, GDP, urban extent and wetlands, and the second most vulnerable in terms of

percentage of total area affected The Mekong Delta is one of the most vulnerable regions of

Viet Nam Therefore, planners and engineers working within the delta, face some of the most

a Lead author and Director of the Southern Institute for Water Resource Planning, 271/3 An Duong Vuong Street,

District 5, Ho Chi Minh City Viet Nam

b AYAD (Australian Youth Ambassador for Development) Water Resource Researcher at the Southern Institute for

Water Resource Planning

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daunting and challenging problems of WRM in the world The success of their response to this

challenge will not only impact the livelihood of some 18 million local inhabitants and the national

economic growth of one of South-East Asia’s development success stories, it will also serve as

an example for other vulnerable nations This places Viet Nam in a unique position, as a nation

with strong technical capacity; it has the potential to become one of the world leaders in climate

change adaptation

This chapter is divided into four parts Section 1 provides an historic outline of water

resources and management in the Mekong River basin and the delta in particular It tracks the

introduction of Integrated Water Resource Management (IWRM) and Participatory Irrigation

Management (PIM) into the management superstructure, the rise of the Mekong River Commission (MRC) and the initiatives of the Vietnamese government in providing for the socio-

economic development of the region and the preservation of vital ecosystem functioning in one

of the most important and diverse river systems in South East Asia, if not the world

Section 2 then tracks the current debate and consensus on climate change (CC),

culminating with a review of the latest findings by the Intergovernmental Panel on Climate

Change (IPCC) Based on experiences of managing water-related extremes in the delta, the

chapter then qualifies what the regional and local impacts of CC will mean to the current regime

of water management in the delta

Section 3 continues by exploring the particular vulnerabilities of the delta community,

the future directions of water resource management, and the important interaction between

disaster preparedness and every day IWRM In particular, this section discusses how these two

fields, often considered mutually exclusive, are being brought closer together in a warming

climate

The final section explores the relationship between national and international stakeholders and how these partnerships themselves need to adapt to CC, if the local communities are to successfully adapt to the rapid changes in our global climate It also

provides some recommendations to direct future efforts and improve the effectiveness of IWRM

in the Mekong Delta

1.1 Water Resources in the Lower Mekong River Basin (LMRB)

The Mekong River is one of Asia’s great rivers: it is 4,200km long with a catchment area

of 795,000km² (KOICA, 2000) It flows through six countries (China, Myanmar, Thailand, Laos,

Cambodia and Viet Nam), incorporates a massive lake system (Tonle Sap Lake) and downstream of Phnom Penh fans out into a series of channels, before discharging into the

South China Sea Due to geophysical and political differences, the Mekong River Basin is

divided into two sub-catchments; the Upper Mekong River Basin, including China and

Myanmar, and the Lower Mekong River Basin (LMRB), considered as the area downstream of

Laos and Thailand The LMRB constitutes 77% of the total catchment area

Biodiversity and basin health

Starting in the Tibetan plateau the river forms a wide variety of habitats, before ending

in the sub-humid floodplains of the Mekong Delta It is the size of the basin, the wide variety of

ecosystems it supports and the minimal regulation of its flow, which contributes to its high

levels of biodiversity and productivity After the Amazon, the Mekong River basin is considered

to have one of the highest levels of biodiversity on earth, including 1,200-1,700 species of fish

(MRC, 2003; ARCBC, 2009) The LMRB is also home to some 60 million people, most of whom

are agrarian farmers and fishermen and therefore dependent on the ecosystem services of the

LMRB for survival For instance, 90% of Cambodians rely on the fish for their protein intake,

while Vietnamese fishermen harvest 400,000 tons of fish annually (Cornford et al, 2002; MRC,

2003; ARCBC, 2009) Most of the historic land clearing has been for agricultural purposes,

most extensively in Vietnam and Thailand, while Laos and Cambodia contain the majority of the

remaining forest systems and deforestation rates of 2-3% of the remnant forest cover (White,

2002)

Climate & rainfall regime

The LMRB has two seasons, the rainy and dry seasons In mountainous regions of the

catchment, rainfall is driven by changes in surface elevation, while the lower reaches of the

basin typically experience rainfall in the afternoon/evening due to convective falls (White,

2002) Rainfall rates are highest in eastern Laos (3,500 mm/yr) and lowest in

north-eastern Thailand (1,000 mm/yr) (White, 2002) Relative humidity exhibits a similar broad range

across the LMRB (50-98%), while evaporation rates show smaller variation (1,500-1,800 mm/yr) (White, 2002)

River morphology & flow

The Upper catchment of the Mekong Basin is rugged, forested and mountainous,

especially in China and Laos It is characterized by steep gorges, narrow river channels and

fast flows Ground cover and surface gradients result in a high sediment content of run-off and

river flows, which are transported downstream As the river approaches Cambodia, the terrain

flattens and the river slows and widens The Mekong Delta starts south of Kratie (Cambodia)

Tonle Sap Lake is one of the dominant hydrological features of the Mekong Delta The lake is a

unique system which regulates flows in the Mekong River by storing water in the wet season

and releasing it in the dry season, providing the base dry season environmental flows and

preserving the year-round integrity of biodiversity and productivity

In total, the annual discharge from the Mekong is about 450 billion cubic metres (4.5%

generated within the Mekong Delta), with an average annual discharge of 13,700m3/s (Phuong,

4

2007; KOICA, 2000) During the wet season, the average discharge can peak at 25,400 m/s,

which results in widespread flooding as the river breaches its banks (Phuong, 2007) In general

flood volumes are greater in the Mekong Delta, but more disastrous in the steeply sloped

upstream sections of the catchment where areas’ water levels can reach up to 10 m

The Mekong Delta generally sees water levels of 4 m or less (Phuong, 2007) During the dry season flows in the upper catchment drop significantly and the flows in the Mekong Delta are sustained by drainage waters from the Tonle Sap system

Sediment dynamics and erosion are one of the key ecosystem functions of the LMRB, connecting sub-catchments thousands of kilometres apart It is estimated that 150million tons of sediment is transported down the main channel into the Mekong Delta, where 138 million tons continues down the Mekong River towards the ocean, while 12million tons flows through the Mekong’s subsidiary channel (the Bassac River) entering the ocean

Figure 1 The Lower Mekong River Basin

The energy potential

One of the contributing factors to the regions biodiversity is the large amount of energy

latent in the natural system Changes in discharges, flow velocities and water levels are the

fundamental drivers of the key ecosystem functions (flood pulse, the swelling of Tonle Sap

Lake and the erosion/sedimentation processes), which in turn, create and support a diverse

array of habitats and life The river’s hydraulic potential is also essential for the agricultural and

aquaculture activities of local communities who rely on the transfer of nutrients, sediments and

freshwater driven by the basins ecosystem functions (ICEM, 2003)

Interactions with non-MRC member states are a growing issue for water resource

management, especially as development initiatives, such as hydropower escalate and the scale

of anthropogenic influences on the rivers hydrology increase The total hydropower potential of

the Mekong River Basin is 54,234 MW (Nguyen et al, 2004) Currently there are 16 dams in the

Mekong River Basin, 14 in the LMRB and 2 in China There are plans for significant expansion

of hydropower developments in the basin, and this is likely to generate complex conflict and

cooperation linkages between riparian countries (Kummu et al (eds), 2008) China plans to

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Deleted: In total, the annual

discharge from the Mekong is about

450 billion cubic metres (4.5% generated within the Mekong Delta), with an average annual discharge of 13,700m 3 /s (Phuong, 2007; KOICA, 2000) During the wet season, the average discharge can peak at 25,400 m 3 /s, which results in widespread flooding as the river breaches its banks (Phuong, 2007)

In general, flood volumes are greater

in the Mekong Delta, but more disastrous in the steeply sloped upstream sections of the catchment where water levels can reach up to 10m The Mekong Delta generally sees water levels of 4m or less (Phuong, 2007) During the dry season flows in the upper catchment drop significantly and the flows in the Mekong Delta are sustained by drainage waters from the Tonle Sap system.¶

Figure 1 The Lower Mekong River Basin¶

Sediment dynamics and erosion are one of the key ecosystem functions of the LMRB, connecting sub- catchments thousands of kilometres apart It is estimated that 150 million tons of sediment is transported down the main channel into the Mekong Delta, where 138 million tons continues down the Mekong River towards the ocean, while 12 million tons flows through the Mekong’s subsidiary channel (the Bassac River) entering the ocean less than 50km to the south of the Mekong A large portion of this sediment washes out to sea where tidal and ocean currents transfer the sediments south-east along the coast to the Ca Mau Peninsula Competing tidal and current interactions cause the sediment to be deposited on the peninsula fringe, which continues to expand by up to 50m a year in some parts The depths of sediment layers

in the delta vary between 20m in the inland areas to up to 500m at river mouths, supporting the hypothesis that most sediment is flushed out to sea before it re-enters the terrestrial environment some 150km to the south east.¶

export a large proportion of the generated power, and Thailand, Laos and Viet Nam have all

initiated plans for increased energy trade with China, while Thailand is also making plans with

Myanmar and Cambodia, and Laos is undertaking similar efforts with Viet Nam and Cambodia

(Kummu et al (eds), 2008) The environmental and social impacts of hydropower on

downstream regions, as well as rising energy demands, are some of the key issues facing the

Mekong Basin, and all riparian nations have a vested interest in both the positive and negative

impacts of this energy source

Figure 2 Hydropower potential

of the Mekong River Basin (%)

(adapted from: White, 2002)

Additionally, the nature of the impacts that the Chinese dams will have is not fully

understood A recent study on China’s existing Manwan Dam found that the infilling of the dam

in 1992 caused record low water levels in various reaches of the Mekong River (Kummu et al

(eds), 2008) A seasonal analysis comparing data from before (1962–1991) and after (1992–

2003) construction of the dam, revealed that while water levels and discharges were

significantly lower during the dry season, during the wet season they increased slightly

Furthermore, there was no significant variation in the monthly means before and after the dam

was built (Kummu et al (eds), 2008) The inter-seasonal variability is likely to be further

amplified by the effects of climate change (see Section 3)

Without question low flows are likely to be reduced further as the demand for water

increases in all the riparian countries of the Mekong, however downstream countries need to

investigate thoroughly the interaction between their demand for imported Chinese hydropower

and the water requirements of other sectors Hydropower dams could either reduce or

exacerbate the inter-seasonal variability in flow depending on the operational regime

implemented It should also be noted that discharge volumes are just one issue of many for a

river basin with increasing hydropower development Other issues – such as sediment

transport, migration of fish species, bank erosion, water quality and land clearing – must also

be considered when assessing the impacts of developing hydropower potential

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1.2 Water Resources in the Cuu Long Delta (CLD)

The Cuu Long Delta (CLD) is the extent of the Mekong Delta within Viet Nam It covers

some 13 provinces and cities, with a total area of 3.9 million hectares and a population of

approximately 17.5 million people (Phuong, 2007) The topography of the CLD is low-lying with

gentle slopes, and an average elevation of approximately 0.7–1.2m above mean sea level In

general, sedimentation processes have built up the banks of the main river channels in the CLD

forming a geographic hollow in the inland areas These hollows form closed floodplains which

store water after the wet season and support wetland and rice-farming systems

The socioeconomic development of the Mekong Delta, exacerbates stress on natural

systems, particularly through agricultural development and living conditions of farmers

Upstream flows into the Mekong Delta

Upstream flows into the Mekong Delta

Rainfall in the Mekong Delta

Tides Strong w inds Salt water

Selection of land and w ater development scenarios

Selection of land and water development scenarios

Objectives for sustainable development:

Ö Production

Agriculture-Forestry-Fishery;

Ö Stable resettlemnt;

Ö Infrastructure development;

ÖEnvironment protection.

Forest Fires

Figure 3 Major impacts and development directions of the CLD (adapted from NN

Tran, 2004)

The major constraints of the natural conditions include (a) flooding over an area of

about 1.4-1.9 million ha in the upper area of the Delta; (b) salinity intrusion (greater than 4g/l)

over an area of about 1.2-1.6 million ha in the coastal areas; (c) acid sulphate soils and the

spread of acidic water over an area of about 1.0 million ha in the lowland areas; (d) shortage of

fresh water for production and domestic uses over an area of about 2.1 million ha in areas far

from rivers, and close to the coastline; and (e) the impacts of global climate change to the flow

regime in the upstream areas, rainfall, and climate in the Mekong Delta and threat from sea

level rise from the sea

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Global climate change and its’ subsequent effects on ecosystems, flooding, drought,

riverbank erosion, water pollution, salinity intrusion, animal and human disease are becoming

more and more difficult to forecast, as well as seriously affecting the production and living

conditions of local people Therefore, in order to further sustainable socio-economic

development including hunger eradication, and poverty alleviation, there is a need to direct the

Mekong Delta towards a general vision of “effective management of natural disasters; wise use

of natural resources for a prosperous and stable economy, and diversification and sustainable

environment in the Mekong Delta"

Climate & rainfall regime

The CLD is under a semi-equatorial monsoon climate with rainfall distributed between

two seasons: the dry season (November to April) and the wet season (May to November) The

average annual rainfall is 1,600mm with 90% concentrated during the wet season There is

minimal seasonal variation in the average annual temperature, which remains about 26oC

throughout the year

Typhoons and storms are irregular events for the CLD under existing climate conditions

Generally low-pressure systems originating in the Pacific Ocean sweep west through the

Philippines and past northern and central Viet Nam, however, occasionally some of these

storms track further south crossing the CLD In recent times major storm events have occurred

and these events are likely to become more common for the CLD under a warming climate

River morphology & flow

Flow in the Mekong is distributed between two seasons During the wet season, it is

driven by runoff in the upstream catchment, in particular the rugged Laos subcatchments In

the CLD water levels rise slowly and peak at 4.0m in September/October, flooding ~1.2–1.9

million ha for 2-5 months (Phuong, 2007) The Tonle Sap Lake is a natural regulatory system

for dry season water levels, and is connected to the Mekong by the Tonle Sap River which joins

the Mekong mainstream at Phnom Penh During the wet season, the high water levels in the

Mekong main channel transfer water into the Lake, quadrupling its size Then, as the channel

water level drops with the onset of the dry season, the system’s hydraulic potential reverses the

direction of flow in the Tonle Sap river, and the lake drains back into the Mekong Delta with an

average downstream discharge of 3,000m³/s and an annual low flow of approximately 2,500

m3/sec During the dry season, salt water intrudes into half of the CLD, and up to 50km up the

main channel (Phuong, 2007)

After Phnom Penh, the Mekong River fans out into a series of channels, with the Hau

(Bassac) and Tien (Mekong) rivers being the two main branches The distribution of discharge

between these channels is important to the hydrologic regime in the upper reaches of the CLD

On average 83% flows through the Tien River (increasing up to 86% in the wet season and

dropping to 80% in the dry season), which then forces lateral flow and flooding in the area

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between the two channels, such that, after the confluence with the Vam Nao River, the

proportions of discharges between the two channels becomes approximately equal to each

other (51%/49%) (Phuong, 2007) This redistribution of flow between the two main river channels has been enhanced by an irrigation canal network and is one of the reasons why the

intra-channel riparian zone is some of the most productive land in the entire CLD The Mekong

river channel reaches a maximum non-flooded width of 1.2km at the Vam Nao confluence

(White, 2002)

Due to the low-lying topography and the fluctuations in the river’s flow regime, the CLD

is affected by two distinct tidal regimes: the semi-diurnal tide in the South China Sea (max

amplitude of 2.5–3.0m); and the mixed tide in the Gulf of Thailand (max amplitude 0.4–1.2m) During the dry season, the tides drive saline intrusion deep in land, while high tides during the

wet season hinder the discharge of floodwaters in upstream areas, exacerbating inundation

times and depths

Based on these hydrological factors, water resources are managed by dividing the CLD

into three distinct areas (Table 1)

Table 1 Hydrological Zones of the CLD (adapted from: Phuong, 2007)

ZONE A Flood Zone Northern part of the CLD, ~300,000 ha including An

Giang and Dong Thap ZONE B Flood and Tidal

mixed zone

~ 1.6 million ha bounded by the Cai Lon River, Xeo Chit rivulet, Lai Hieu Canal, Mang Thit-ben Tre rivers and Cho Gao Canal

ZONE C Tidal zone ~ 2.0 million ha along coastal areas, especially

adjacent to the South China Sea

The flood pulse

The flood pulse is perhaps the most important process in the ecology of the floodplains,

and the main reason for the delta’s high productivity It facilitates the transfer of water to dry

land and plant matter to the water, the latter provides energy and nutrients for the aquatic biota,

while both facilitate biomass transportation (Phuong, 2007; Kummu et al (eds), 2008) The flood

pulse is characterized by its timing, duration, amplitude, spatial extent, continuity, number of

peaks and rate of inundation and subsidence (Kummu et al (eds), 2008) Most of these

characteristics are vulnerable to changes in the flow of the Mekong River In the future, flow in

the CLD is likely to be affected by the dramatic escalation in upstream hydropower dams,

conflict in water sharing based on increased agricultural activity in newly developing countries

such as Cambodia, increased run-off in the mountainous catchments of China and Laos due to

deforestation and other land-clearing practices, and also climate change Furthermore, there

will also be feedback between these impacts, for example climate change and hydrodams will

increase inter-seasonal variability, or the dams could stagger their releases to synchronize with

the dry season and thus curb reductions in the low flow of the Mekong River

Human communities and their influence

Over hundreds of years, farmers have built up a complex system of irrigation and

drainage works in the CLD to support agricultural activity To this day, fishing and farming

remain the key economic activities in the Mekong Basin, making water resource management

one the most important management issues Rice crops dominate agriculture in the LMRB, with

up to three crops a year in highly developed areas and just one rain-fed crop in less developed

regions However, other crops include maize, vegetables, mung beans, soya beans, sugar

cane, fruit trees and coconuts (Phuong, 2007) Aquaculture and fisheries in the LMRB are two

of the oldest and most important sectors Inland areas are dominated by fishing, especially in

the Tonle Sap system, while coastal areas utilize estuarine environments to support shrimp

farming

Of the 17.5 million people in the CLD, nearly 80% live in rural areas (Phuong, 2007)

Population density is strongly correlated to proximity to fresh water sources, highest densities

occur along the Hau and Tien rivers (i.e Zone A and B), while areas of Zone C (Ca Mau, Bac

Lieu and Kien Giang) have some of the lowest population densities Farm land per capita

follows a reverse pattern, along and between the Hau and Tien rivers the average farmer has

0.1 – 0.2ha, increasing to 1ha per farmer in more remote areas (Phuong, 2007) The economic

basis of the CLD remains in the sectors of agriculture and aquaculture (generating 70%-90% of

the income), however recent years have seen the diversification of the local economy,

especially with the growth of the industrial and manufacturing sectors Average income

per-capita is estimated at 400 – 470USD, however distribution is uneven, with 20 – 30% of the

population living in poverty (Phuong, 2007)

Most of the existing irrigation works in the CLD were built during the 1960s, and 1970s

In 2002, the system supplied water to only 50-60% of the design command area (Molle, 2005)

The Government of Vietnam, recognizing the massive outlay required for infrastructure works,

estimates that USD $750 million is required for repairs and improvements to the existing

system (Oxfam, 2008) It should also be noted that currently, sediment deposition is not

transferred to the floodplains concentrating in the bottom of river channels and canals, due to

inefficiencies in the water distribution network

Development plans, especially in the deltaic areas of Cambodia and Viet Nam, aim to

increase food production through a combination of expanding crop areas, intensifying

production and improving yields (KOICA, 2000) In Viet Nam, development plans also include

expansion of aquacultural production, enlargement and specialization of fruit tree growing

areas and the controlled expansion of industrial and shipping activities The main issues facing

agricultural communities in the LMRB are; acid sulphate and saline soils, flooding, drought,

freshwater shortages, storm events, sedimentation, bank erosion, and saline intrusion

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Wetlands

There remain several key wetland areas of high regional significance These include

Dong Thap Muoi, Mekong River Estuary, Minh Hai melaleuca forest, Bac Lieu coastal marshes,

Dam Doi bird colony, Cai Nuoc bird colony and Nam Can mangrove forest (ARCBC, 2009) Six

reserves have consequently been established protecting some 20,671 ha of the total 290,000

ha of remnant wetlands (ARCBC, 2009) The support and expansion of these areas is crucial

for survival of the deltaic flora and fauna, and efforts to establish the Tram Chin Nature Reserve

in the 1980s have already seen the return of the Sarus Crane, once thought to be near

extinction (Pacovsky, 2001)

Water quality

Currently, the high volumes of flows in the Mekong system possess very efficient

flushing properties; consequently there are no significant problems with water quality in the

CLD However, the continued intensification of agricultural activity will see continued growth in

use of pesticides and fertilizers, new industrial developments are likely to increase the pollutant

loading of the delta’s waterways and population growth will increase domestic waste loads, the

combination of which may pose serious risks to water quality

Water quality will also be affected by the timing of river flows Changes to the flood

pulse and inter-seasonal variability could increase wet season erosion, while increased water

scarcity in the dry season could result in concentrated contaminant pulses (DWR, 2008)

1.3 Water-related extremes & management issues

According to the Asian Disaster Reduction Centre (ADRC), the main natural disasters

facing Viet Nam include windstorms, floods, epidemics, droughts, insect infestation, landslides,

wildfires, with floods droughts and windstorms affecting the most people in recent years

(ADRC, 2006) Floods, other high rainfall storm events and droughts dominate water-related

extremes in the CLD Water management issues are determined by the season, during the wet

season the main problems are flooding, erosion and the leaching of acidic soils, while drought,

fresh water shortages and saline intrusion are the main issues for dry season water management

Flooding

The main factors influencing flooding are; topography, upstream precipitation, regime

flow and run-off, regulation of Tonle Sap Lake, the two tidal regimes, local rainfall and the

existing infrastructure system All of these factors undergo continual changes between seasons

and even between days, resulting in a complex flood signature in the CLD, forcing communities

to develop a high level of resourcefulness and adaptability in order to prosper, even without

climate change

Flooding in the CLD occurs from June to December with a one-month lag on upstream

floods Floods travel at 1.5-2.0 km/hr between Phnom Penh and Tan Chau, though they can be

slowed if their arrival is synchronized with high tides On average, flood waters rise and fall by

5-7 cm/day, with observed maximum rates of up to 12 cm/day during big or early floods

(Phuong, 2007) The flood hydrograph usually displays 2 peaks, the lead peak generally occurs

in late August, followed by the dominant peak in the middle of September/beginning of October,

although in rare circumstances the two peaks can be separated by up to 54days (Phuong,

2007)

Typically, 38,000m3/s enters the CLD during normal flood seasons, peaking at

43,000m3/s during extreme floods (Phuong, 2007) Approximately 82-86% of floodwaters enter

via the two main river channels, while the remainder crosses the Cambodian border as

overland flow It is this overland flow which dominates flooding in Zone A due to local

geomorphology and topographical features (Phuong, 2007)

For water management purposes, floods are divided into three categories, based on the

water levels measured at upstream gauging stations (figure 3) The similar probabilities of

average and big floods give an indication of the high level of variability in the flooding regime

Figure 4 CLD FLOODING: (left) Categories based on river stage recordings & probability of

occurrence; (right) typical area of annual flooding in the Mekong Delta (adapted from: Phuong,

2007; Nguyen, 2009)

The widespread irrigation and drainage works used to make the CLD more productive

have had some effects on the inundation regime Specifically, in deep inundation areas they

have changed the direction and water level in the fields at the beginning of the flood season,

and altered the signature of the main flood in shallow inundation areas

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One of the key changes in WRM in the CLD is the acknowledgement that communities

must live with floods, and that flooding brings both negative and positive effects to the delta

(MARD, 2003) The negative impacts are well known (Table 2), however flooding also leaches

the soils of acid, controls harmful insects and fish populations and deposits a huge volume of

sediment

Table 2 Estimated damage from big floods in the CLD (adapted from: Phuong, 2007)

CLD Unit 1994 1996 2000 2001 2002

1 Estimated total VN Dong (Billions) 2,295.6 2,182.3 4,597.3 1,456.0 456.8

2.Agricultural production VN Dong (Billions) 1,326.4 1,036.0 948.5 372.5 216.1

- Rice reduced productivity Ha 83,981 92,984 198,328 33,036 15,777

- Rice Completely loss Ha 53,994 30,869 57,714 8,955 365

- Orchard seriously damaged Ha 12,145 1,161 4,613 4,985 1,049

- Industrial plant and upland crops Ha 55,497 76,396 63,560 32,785 32,142

Drought

The other major extreme of the climate regime, is drought Drought is often

underrepresented in discussions about disasters in the CLD, because this is normally a region

associated with an abundance of water and the problems associated with this excess,

furthermore droughts usually operate over a much more subtle time frame than flooding and

can last several years compared to a matter of months or days for storms and flooding The

most recent drought of significance for the CLD occurred in 2004 (Oxfam, 2006) According to

community surveys undertaken by Oxfam (2006), not knowing what to do in droughts and

insufficient water storage capacity were considered to be major limitations in drought-risk

management

Predictions suggest that climate change will increase the inter-annual variability in

weather patterns, increasing rainfall in the wet season, decreasing rainfall in the dry season,

shifting the timing of the flood season and prolonging the duration of drought spells (Oxfam,

2006) The study found that despite progress in development works, communities in some

provinces believe they are becoming more vulnerable to natural disasters such as droughts and

floods, which are either the result of increasing vulnerabilities despite development initiatives or

those development initiatives have failed to instill confidence amongst communities Both of

these are serious, but they will require different methods of resolution In response to the

former, the main issue is lack of sufficient knowledge, experience and financial capacity to

undertake adaptation works, while failure to instill confidence in communities about

development initiatives is largely due to issues of knowledge and technology transfer as well as

human resource management and insufficient community participation (Table 3)

Communities were often aware of long-term drought mitigation programs, however, they

often felt no ownership or responsibility for them (Oxfam, 2006) Instead, communities primarily

responded first, by preserving food and seed NGOs typically responded by providing

water-storage facilities, supplying food grains and disaster training (Oxfam, 2006) Local government

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responses included provision of food grain, building and maintaining community wells and

establishing volunteer community water supply teams, while the central government provided

food and financial assistance (Oxfam, 2006)

Table 3 Limitations of current drought management initiatives (adapted from: Oxfam, 2006;

• Absence of policies for agricultural assistance, and

poor participation of appropriate authorities in

decision making and development planning,

• Lack of long-term drought preparedness programs,

• Conflict between socio-economic sectors,

• Overlap in authority and decision making powers in

administrative management,

• Lack of regulations for water exploitation,

• Insufficient irrigation management and poor

community participation in long-term drought

mitigation programs,

• Lack of drought resistant crops and animal breeds,

• Lack of financial support during droughts, and

deficits during irrigation projects, and

• No specific budget for drought preparedness at the

provincial level and below

• Lack of knowledge on drought preparedness,

• Lack of information on appropriate agricultural practices,

• Lack of technical capabilities and staff to advise farmers,

• Ill-informed communities and some organs of the

government about the implications of climate change, droughts and the environment

• Lack of community participation

Saline intrusion

The large seasonal fluctuation in river flow results in changes in the hydraulic differential

between river and oceanic water levels During the dry season, low water levels in the river

allow tides to drive salt water into approximately half of the CLD area (Fig 4)

Salinity levels of 4ppt can penetrate 50km up the main channels and 100km up the

tributaries such as the Vai Co River (Phuong, 2007) In Ben Tre province alone, saline intrusion

was responsible for USD $37 million worth of damages and productivity losses during 2005

while almost 40% of the provinces population went without fresh water supply during the dry

season (Oxfam, 2008)

The management of saline intrusion is one of the key issues of WRM, because water

salinity determines the type of activity that an area can support There continues to be conflicts

between rice and shrimp farmers, driven by the development objectives of the government,

fluctuations in the domestic and international market price for rice/shrimp products and the

desires and flexibility of local farmers

14

Figure 5 CLD Water Resource Extremes: (left) Maximum salinity intrusion; (right) Maximum

water level in flood season (T.V.Truong, 2008)

Typhoons and storms

Unlike the north and central coasts of Vietnam, the CLD has not been regularly hit by

storms and typhoons However, there have been some catastrophic typhoons in recent times,

the most significant of which was Linda Storm (1997) Linda storm was travelling at 28m/sec

when it hit Ca Mau Peninsula before crossing into the Gulf of Thailand, the typhoon destroyed

more than 200,000 homes, ruined 500,000ha of farm and aquacultural land and killed 355

people (Table 4) (Dillion et al, 1997) The damage was amplified by the fact that the CLD was

largely unprepared for such a disaster and therefore had minimal disaster response systems in

place Because storms originate in the Pacific Ocean, the impacts are concentrated around the

coastal areas of the CLD These areas also correspond to some of the highest levels of poverty

and isolated communities

Table 4 Damage cause by Linda Storm in the CLD (SIWRP, 2008)

Acid-sulphate soils remain a problem for 0.9 – 1.0 million ha of the CLD The soil matrix

is the result of fresh and marine water interactions, as sulphur from the oceans and nutrients

from terrestrial flows formed a layer of sulphate and saline sulphate soils Acidic waters are

generated when exposure to oxygen initiates an oxidation process with acidic by-products

contaminating the first flush of rain with detrimental effects on both the receiving environment

and rice production However, over time a complex layer of vegetation including floodplain

wetlands, expansive grass plains and scattered Melaleuca formed a rich topsoil of

decomposing organic matter which isolated the potentially acidic underlying layer from contact

with oxygen, rendering them inert Changes in land-use patterns – most notably clearing for

agricultural production and the control of wet season flooding – has exacerbated the problem

Drainage works have had some success in flushing these acidic waters out to sea, limiting the

problem to the months of May-August and November-January The issue is compounded

during dry years when there is a shortage of water

Table 5 CLD: General overview of the major risks

CLD RISK FREQUENCY EFFECTS AREA EFFECTED

Floods ƒ Annually (June –Dec)

ƒ Water level ~4m (rising

average ~5-7cm/d)

ƒ “Large Floods”

(>4.33m) have a 46%

probability of occurrence

ƒ sustains key ecosystem functions

ƒ provides water for agriculture

ƒ destroys homes, infrastructure, farms

ƒ can result in loss of life

ƒ ~49% of CLD

Saline

Intrusion

ƒ Annually (dry season) ƒ Saline concentrations

greater than 4ppt can change environments from fresh to saline

ƒ ~50km up the main channel

ƒ ~50% of CLD Droughts ƒ last major drought

ƒ water shortages for domestic use

ƒ mainly effects coastal areas, the Plain of Reeds, and Long Xuyen

Quadrangle, which can become hydrologically isolated from freshwater if the rivers do not breach their banks

Typhoons ƒ Last major storm 1997

(Linda storm), 2000 was also a significant event

ƒ Destruction of homes and infrastructure (canals, roads dykes)

ƒ Coastal provinces (Ca Mau, Bac Lieu, Soc Trang, Ken Giang)

16

2.1 Global perspective

Although human-induced climate change has slowly been occurring over centuries,

awareness of the phenomena is a comparatively recent development Arguably it was not until

the 1992 Rio Earth Summit that the issue began to receive international attention Since then,

progress on emissions controls has resulted in significant debate and few global measures

However, it should be remembered that there are two sides to the global climate change

response; mitigation of emissions levels and adaptation to changes in the biosphere CO2

emissions have largely been the consequence of industrialization in the developed world and

consequently their efforts have focused on emissions control On the other hand, the developing world correlates to areas which are most vulnerable to the impacts of climate

change and so adaptation has become an urgent necessity (World Bank, 2007; Oxfam, 2008)

Scientific understanding

There are two fundamental drivers of climate change, the natural or base fluctuations in

global climatologic parameters, and the influence of anthropogenic activities It is widely accepted that surface temperatures on earth have fluctuated dramatically throughout its history

as part of ongoing long-term geo-physical processes, and these days there is also consensus

amongst the scientific community that global temperatures are increasing Furthermore, most

research indicates that human activities have played a decisive role in accelerating this process

during the last century, such that climate change is now happening faster than at any other

stage in the earth’s history

The Intergovernmental Panel on Climate Change (IPCC), one of the leading research

bodies on the phenomena, have recently released their fourth Assessment Report (AR4) It

concludes that the concentration of carbon dioxide in the earth’s atmosphere has fluctuated

around a natural range of values for the past 650,000 years, however, recent CO2 levels have

consistently exceeded this range (IPCC, 2007) Consequently, 11 of the warmest years, observed since instrumental records began in 1850, occurred during the last 12 years (IPCC,

2007) Furthermore, there has been an increase of 0.740C in the average temperature during

the 20th century, with predictions of future global temperature rises in the order of 1.8 – 4.00C

(IPCC, 2007) These temperature changes will have effects across the biosphere, but especially to the hydrological cycle, including changes to sea levels, precipitation and monsoon

patterns and glacial melt

Globally, climate change is expected (with a high degree of confidence) to have an

overall negative impact on freshwater systems (IPCC, 2007) Sea levels have already risen by

17 cm during the past 100 years and are predicted to continue rising Predictions of the

magnitude of sea level rise vary greatly

2.2 Regional perspective

Viet Nam is located in the tropical region of Asia and is potentially one of the countries

where a rise in sea level could have the most dramatic impact with nearly a quarter of its

population directly affected (World Bank, 2007) The IPCC suggests that Vietnam is also likely

to face both drought and changes to the prevailing precipitation and flooding regimes (IPCC,

2007) Viet Nam has a population of 84 million, the majority of whom live along its 3,200

kilometres of coastline It suffered 10 typhoons and severe storms in 2007, and concentrates

much of its food production in the low-lying Mekong and Red River deltas If sea levels rise by

one metre, Vietnam would lose more than 12 percent of its land, home to 23 percent of its

people Climate change could also increase the frequency and severity of typhoons, and rising

temperatures and changing rainfall patterns would also affect Vietnam's agriculture and water

resources Vietnam’s economy grew by over eight percent last year, and is one of the fastest

growing economies in Asia At the same time, it is also emitting more pollutants, with the

amount of greenhouse gases (GHGs) released projected to increase by a factor of 2.3 during

1994-2020

The IPCC Technical Paper on Climate Change and Water (Bates et al, 2008) outlines

the effects that Climate Change is having on the hydrological cycle By the middle of the 21st

century water availability is expected to shift away from arid, semi-arid and dry tropical areas

towards wet tropical and higher altitude areas Therefore, river run-off is expected to increase in

parts of the LMRB, and there is a likely increase in the risk of flooding and drought, with an

increase in the frequency of heavy rainfall and extreme events (typhoons, hurricanes), simultaneously, drought frequency is increasing and lasting longer Natural disasters in China

will challenge the integrity of large hydropower projects, both of which could have disastrous

effects on the downstream communities and ecosystems of the LMRB Traditionally, typhoons

have been a problem for central and northern Viet Nam, however global warming is likely to

see typhoons tracking further south as well as becoming less frequent but more catastrophic

Increasing water temperatures and changes to flooding/drought regimes are expected

to affect water quality, exacerbating effects from pollution such as sediments, nutrients, pathogens, pesticides, dissolved organic carbon, and salt There will be significant economic,

environmental and health-related ramifications for human communities These changes to the

hydrological cycle are expected to reduce food security and increase vulnerability of rural

farmers, especially in the Asian megadeltas

Additionally, climate change is compounded by other global development problems of

rapid population growth The UN predicts that for the first time in the world’s history 2009 will

see one billion people suffering from hunger

18

2.3 Local perspective

Climate change is altering the flood regime in the Mekong Delta The following are

some key problems associated with these changes:

Table 6 CLD Summary of the Impacts of Climate Change

Environmental

Characteristic

Impacts Of Climate Change

Temperature ƒ Temperature increase by 0.1Deg C every decade 1931-2000

Rainfall ƒ Annual rainfall average is constant but greater polarization of

wet and dry seasons

ƒ Higher frequency and longer duration of drought in southern areas of Vietnam,

Storms ƒ Fewer typhoons, but greater intensity/severity and they are

tracking further south Sea Levels ƒ Sea level rose 2.5 – 5.0cm each decade for the last 50years

ƒ SLR 30-35cm (2050), 40-50cm (2070), 60-70cm (2100) River flow ƒ Mirrors increased polarization of rainfall

ƒ Flows in the Mekong to increase 7-15% in the wet season, decrease 2-15% in the dry season

of river traffic and increased pollution

Biodiversity ƒ Severe reduction in natural fish stocks

Sea Level Rise (SLR)

The quantification of SLR is difficult, because it incorporates several biophysical processes, such as glacier and terrestrial ice sheet melt, thermal expansion of the ocean

column, snowmelt, and changes to the water content in terrestrial and atmospheric regions

(figure 6) These factors need to be modeled separately and then combined to give an overall

indication of SLR Therefore, estimates of SLR by 2100 range from 0.5m to 70m (BBC, 2008) The process which is least understood is the melting of glaciers and terrestrial ice sheets,

consequently the IPCC omitted these factors in their estimates of SLR, predicting that SLR

would likely be less than 2.0m by the end of this century (IPCC, 2007; BBC, 2008) A study by

the World Bank (2007) on the impacts of SLR on developing nations modeled SLRs of 1.0, 3.0

and 5.0 m, with 1-3 m being considered realistic

The results of the World Bank study are sobering for Viet Nam Of the six critical

elements under study, Viet Nam was the most effected nation in the world for four of these

categories (Wetlands, Urban extent, GDP, population) and the second most affected for the

remaining two categories (Land area, agricultural extent) (World Bank, 2007) Furthermore,

most of these effects will be concentrated on the mega-deltas of the Mekong and Red rivers

There are three measures to cope with sea-level rise: protection, adaption and

withdrawal The first step towards effectively coping with SLR is a thorough study to quantify

and determine specific regional areas that will be affected by SLR in accordance with

development scenarios The simulations of impacts of the nature and the socio-economy under

different sea-level-rise and upstream development scenarios need to be implemented in order

to find out reasonable measures/solutions For water resources development, the ready-made

plan needs to be re-planned, calculated, supplemented, adjusted in accordance with new

parameters/values of hydrological and hydraulic division, and initiate the short-term and the

long-term structure and non-structure measures/solutions

The above assessments are based only on the forecast of IPPC and WB, as well as

preliminary estimation of SIWRP However, newest information on climate change and sea

level rise on the world recently shows that the trend of sea level rise progress will happen faster

than previously forecasted The phenomena of sea level rise exist and cannot be avoided

Therefore, considerations to cope with effects of the sea level rise at this time are really urgent

There will be increased inter-seasonal variability between the wet and dry seasons

affecting precipitation regimes One study suggests that rainfall will increase by more than 17%

in the wet season and reduce by more than 27% during the dry season (see Figure 7) This is

likely to increase the frequency and severity of droughts as well as of floods

Figure 8 Predicted Max/Min % changes in flow averages (adapted from: Hoang et al, 2004)

Table 7 General Summary of Climate Change impacts on the CLD

Water

Resources

ƒ Increased variability between wet and dry season rainfall

ƒ Increased frequency and severity of droughts and climate extremes

ƒ Growing disparity between water supply and demand signatures

ƒ Increased vulnerability to changes in the flow regime and river regulation (e.g from hydropower)

Agriculture,

Forestry &

National food

security

ƒ Changes to plant growth, yields, disease risk & crop failure

ƒ Altered timing and number of annual crop cultivation cycles

ƒ Increased risk of plant disease

ƒ Reduced available arable farm land

ƒ Increased fire risk and anthropogenic deforestation/forest degradation

ƒ Increased vulnerability to continuing deforestation which will alter runoff regime in the upstream catchments of Laos (where 30% of flow originates) This could increase sediment loads and

exacerbate worsening flooding problems & infrastructure inefficiencies in a warming climate

Fisheries ƒ Reduced habitats for freshwater species

ƒ Increased aquaculture potential Transportation,

construction

and industry

ƒ Increased flood risk for roads

ƒ Increased erosion of road surfaces

ƒ Increased risk of low flow conditions inhibiting navigation

ƒ Increased erosion in wet season (already 70 identified sites of

Deleted: 6

Deleted: 7

erosion) Disasters ƒ General increase in the frequency of natural disasters

ƒ Typhoons tracking further south and hitting with increasing severity

Population ƒ Increase in environmental refugees and migration pathways

ƒ Increased urbanization will place greater strain on water shortages which are likely to last longer and become more pronounced with climate change

2.4 Qualitative Assessment of Climate Change Risk

The field of ecology owes its development and success to a recognition that the scale of

inquiry is fundamental for a more accurate understanding of the biophysical processes, and

climate change itself, is perhaps the highest profile example of the importance of scale In the

past CO2 emissions were seen as inconsequential, because they seemed small in comparison

to the size of the atmosphere, but at the global scale and over a hundred year time frame they

managed to induce an incremental change in the atmospheric temperature which has produced

much more influential subsidiary effects that now threaten many human communities

The risk facing the CLD is occurring over two temporal scales On the one hand, WRM

must plan for the day-to-day realities of communities, matching water distribution, quality and

development to long-term socio-economic and ecological needs of the community and their

living environment On the other hand, WRM must also accommodate for disaster management, mitigating the impact of disaster events on the local community as well as

providing for emergency response measures in service and rehabilitation While the management initiatives for many of these issues may overlap, and others may already exist,

climate change will force better coordination of efforts at all spatial and temporal scales

Lastly, Viet Nam and the CLD in particular, must acknowledge that while they played

only a minor role in the escalation of human-induced climate change, they must take control of

adaptation responses to the subsequent impacts, and look to encourage large emitters to do

the same

3 Water Resource Management - mitigation and adaptation initiatives for

Climate Change

3.1 Integrated Water Resource Management (IWRM) – Role for climate change

mitigation and adaptation

Water resources in the Mekong River, are defined by the Mekong River Basin, which

extends over 6 countries, 60 million people and many different ethnic groups and climatic

regimes The Mekong River, therefore, is a prime candidate for Integrated Water Resource

Management (IWRM)

IWRM concept and history

22

IWRM is defined as a “… multi-resource management planning process, involving all

stakeholders within the watershed, who together as a group, cooperatively work toward identifying the watershed’s resource issues and concerns as well as develop and implement a

watershed plan with solutions that are environmentally, socially and economically sustainable”

(ADPC, 2006) Additionally, IWRM acknowledges that the scale of inquiry, when addressing

issues, is fundamental to the type of solution that will be generated This approach constructs

local issues as ‘nested’ within the broader context of basin decision-making (Miller, 2003) It

recommends that issues be seen in the context of the whole river basin, so that all stakeholders

can have their concerns and interests addressed and negotiated resolutions to problems can

be generated in the most equitable manner Additionally, water resources, while being a sector

onto itself, is also an important component of many other sectors of riparian communities

consequently IWRM planners need to be conscious of the externalities that drive water

resource exploitation

The introduction of IWRM is closely tied with the emergence of the Mekong River

Commission (MRC), which first manifested as the Mekong Committee, a UN-led initiative in

1957 (MRC, 2008) At that time the LMRB was seen as one of the world’s great ‘untamed

rivers’ and its vast reserves of freshwater could form the backbone of economic development in

the newly emerging independent nations of the basin Earlier efforts were inspired by the

example of the Tennessee Valley Authority (TVA) which in its prime was considered one of the

basin-wide management success stories (Miller, 2003) During the 1960s US engineering skills

were transported to the Mekong in line with the TVA model to develop its hydro-electric

potential This can be seen as the precursor to IWRM in the LMRB, when engineering-based

intervention with a strong sectoral focus looked to kick-start economic development (Miller,

2003) Then political instability led to the collapse of the Mekong Committee in the late 1970s,

to be reborn in 1995 as the MRC with a new mission of sustainable development for the

Mekong River Basin At this time one of the leading examples of best practice was the

Murray-Darling Basin in Australia, however, both this and the previous TVA model were developed in

post-industrial societies and their transference to the LMRB was based on some assumptions

which have suffered some criticism (Miller, 2003) According to Miller (2003) “…the issue is not

so much one of whether or not international experience is relevant, but rather of what is

relevant – packages and models, or processes and principles?…” and if it’s the latter, then how

can development initiatives improve on their ability to pass on processes and principles in

vastly different socio-economic environments and in the midst of political and cultural institutions that bear little in common with those where the IWRM models were first proposed

and developed As will be shown, these concerns remain relevant to the CLD today

In 1995 the Mekong River Agreement (MRA) was signed with the main purposed of

regulating the construction of hydro-dams on the Mekong mainstream Then, IWRM was

formally coupled to the Vietnamese political will in the government’s 1999 Law on Water