Mekong Utility Watch

Environmental threats to the Mekong Delta

February 17, 2000

A World Bank-funded development programme in Vietnam’s Mekong Delta aims to shift the delta’s water management regime from the current system, which is relatively open and adapted to the natural flows of the Mekong, to one reliant on large-scale infrastructure for the control of salinity intrusion and flood protection. The Bank’s plans are intended partly as a response to the delta’s vulnerability to impacts resulting from large-scale infrastructure and other conventional economic development in the Mekong River Basin. The World Bank’s intervention also aims to support the national objective of further intensifying rice production in the delta. Fiona Miller explains how the implementation of the programme will multiply the environmental problems confronting people living in the Mekong Delta.

Vietnam is the last country through which the Mekong River flows before it ends its 4, 800 kilometre journey to the South China Sea. After the confluence of the Tonle Sap and Mekong Rivers, at Phnom Penh in Cambodia, the Mekong divides into two branches, known in Vietnamese as the Tien Giang (Mekong River) and the Hau Giang (Bassac River). These then divide into nine smaller tributaries, giving rise to the delta’s traditional name of Cuu Long (Nine Dragons). Every year, the Mekong’s floodwaters bring alluvial soil from upstream in the basin, creating the fertile and dynamic ecosystem of the delta. The fish, wetlands and rice fields of the delta have come to rely on this seasonal supply of fertile silt.

Vietnam’s location as a downstream country endows it with an immensely fertile delta of great national economic, ecological and social importance. However, Vietnam is also highly susceptible to the impacts of upstream development interventions with negative environmental impacts.

Vietnam is both an upstream and downstream actor in the Mekong River Basin. This dual positioning has resulted in a mixed response within Vietnam to the social and environ- mental threats facing the delta. Vietnam has been vocal about the nation’s downstream interests within the Mekong River Commission. However, development in the country’s Central Highlands (Tay Nguyen), which is also within the Mekong River Basin, has damaged the means of livelihood of local communities living downstream in both Cambodia and the Mekong Delta in Vietnam.

Environmental threats

Since the early 1990s, efforts to integrate the economies of the six countries of the Mekong Basin have resulted in many large-scale water development projects throughout the region. The Asian Development Bank (ADB), World Bank, and aid agencies and corporations from industrialised countries have played the dominant role in the promotion of these plans, which include hydroelectric dams, large-scale water diversions for irrigation and water supply, and the expansion of chemical intensive agriculture and rapid industrialisation. The increase in regional trade, facilitated by these agencies, has also contributed to extensive deforestation in the Mekong River Basin.

This existing and planned development presents considerable environmental risks to downstream communities. Dams, both in the Mekong tributaries and on the mainstream, alter the natural flows of the river thereby damaging ecosystems that are adapted to natural water flows. Dams also block sediment flow and fish migrations. Meanwhile, the release of chemical and agricultural pollutants in the Mekong basin waterways limits agricultural and fishing productivity and reduces potential sources of freshwater for riparian communities.

The forests throughout the Mekong basin perform important flood regulation functions, absorbing the high floodwaters during the rainy season to be slowly released in the dry season. Extensive deforestation increases the severity of flooding as rainfall on deforested areas washes quickly into river ways instead of being partially absorbed by forests. These ‘quick-rising’ big floods pose risks to riparian farmers who plant rice and vegetables on the banks of rivers in anticipation of beneficial silt-laden ‘slow rising’ floods. Rapid flooding often washes away crops, reducing rather than increasing riparian fertility and causing food security problems in the affected areas.

Severe flooding is a serious environmental risk confronting communities in the Mekong Delta, and the severity of flooding has increased over the past 10 years. This increase in the unpredictability, frequency and magnitude of floods has been responsible for high human and material costs in the delta, especially for farmers located in the upper delta, where floodwaters reach depths of two to four metres.

Where the river meets the sea

The area where seawater and freshwaters mix as rivers meet the sea is an important ecosystem in healthy estuaries, forming a highly productive habitat for aquatic and marine fauna and flora.

During the dry season, when the flow of the Mekong decreases, seawater flows from the sea up through the network of canals and waterways in the delta. Of the 3.9 million hectares (ha) of the Mekong Delta, up to 2.1 million ha are affected by salinity from seawater each year.

Several development interventions in the Mekong River Basin have contributed to increased salinity intrusion by reducing the dry season flow to the delta. As the flows are reduced more seawater flows into the delta expanding the severity of salinity intrusion and the area affected. The most significant cause of increases is the continual development of irrigation and use of water for intensified agriculture throughout the region. This is particularly significant in the middle and upper delta in Vietnam where double and triple cropping of rice each year is dependent on ever-increasing extraction of dry season flow volumes. Deforestation throughout the region also impacts on dry season flows as forests play a role in storing water.

Future development plans in the region include massive water diversion schemes that would divert water out of the Mekong basin mainly for irrigation and water supply. Lao PDR is currently implementing large-scale irrigation programmes supported by multilateral and bilateral aid, and is also planning to sell massive quantities of water to Thailand. None of these plans take the impact on downstream countries into account. (See Watershed Vol. 4. No. 2)

Environmental threats to the delta from upstream development interventions pose some challenges for traditional methods of adapting to flooding and salinity intrusion. The solution posed by the World Bank, and other conventional development institutions is the construction of large-scale infrastructure. These same institutions, who are now promoting ‘fortress’ type solutions, are responsible for promoting the near-sighted development that has caused these challenges.

The new, World Bank-funded phase of development in the Mekong Delta supports the construction of infrastructure, such as dykes and sluice gates, with the aim of preventing saltwater intrusion and extending the area of multiple rice cropping (two to three crops per year) in the saltwater- affected zone. [See Box: Mekong Delta Water Resources Project]

Conversely, local communities in the delta have developed open and flexible technologies for living with the ebb and flow of the Mekong floods and variations in rainfall and with salinity intrusion. This adaptive approach is reflected in the local saying “shaking hands with the flood” and is based on a diversification of agricultural and livelihood options.

“Shaking hands with the flood”

Many unique traditional livelihoods existed in the flood- affected regions of the Mekong Delta, based on the collection and cultivation of floating and deepwater rice and the capture of wild fish, prior to the expansion of high-yield variety rice cropping this century. Archaeological evidence confirms that the first area to be settled in the delta was not the shallow- flooded middle delta, but instead the flood-affected upper delta near the Cambodian border where people collected wild floating rice. This practice was maintained in the Plain of Reeds until 1977.

Floating rice has been cultivated in the deep flooded areas for over 150 years. Sowing commences with the annual rains, the rice stalk then rapidly lengthens as the floodwaters gradually rise, growing to a height of two to three metres. After several months the rice plants collapse with the receding waters and then flowers before being harvested. The cultivation of upland crops, such as mung bean, following the floating rice crop benefits from the capture of silt and other nutrients by the long stalks of the floating rice.

In the shallow flooded zone of the middle and upper delta, farmers have developed a double-transplanted deepwater rice system appropriate to the local flood and tidal regime. One month after sowing when floodwaters begin to rise farmers transplant the rice seedlings, then just before the peak of the flood two months later the rice is transplanted again. The rice is harvested just after the floods recede.

Although the traditional varieties used in such systems have a lower yield than high-yield variety rice they display key environmental and economic advantages. Both the systems are highly adaptive to the annual cycle of flood waters and are reliant on the flood’s silt and nutrients to maintain soil fertility. These traditional rice systems produce stable returns yet require little to no tillage and use of expensive puts such as chemical fertilisers and pesticides. Farmers in An Giang province, involved in studies with the Cuu Long Delta Rice Research Institute and Can Tho University, have shown that by planting floating rice in rotation with dry season crops, such as soy beans, peanuts, mung beans, fruit, sesame and corn, the financial returns are comparable to cultivation of two crops of short duration high-yield varieties. However, the area under floating rice has decreased over recent years from 500,000 ha in 1975 to less than 50, 000 ha in 1995.

Farmers in the Mekong Delta have developed more than 1,000 traditional rice varieties. These are highly valued for their taste, fetching higher prices than high-yield variety rices, and often form an essential ingredient in traditional dishes at cultural festivals, such as Tet (Vietnamese New Year). However, these traditional varieties have been rapidly replaced by high-yield variety rice promoted through agricultural extension programmes; less than 150 traditional varieties are now being cultivated in the Mekong Delta.

Fish forms an essential part of the diet and culture of people living in the Mekong Delta, comprising more than half of people’s daily protein intake. People who do not have access to land or unable to cultivate during the peak flood period have traditionally caught wild fish previously abundant in the Mekong waterways. Wild fish also enter rice fields during flood periods to feed until waters recede. However, as natural fish numbers have declined over the past decade, those with land have sought to adapt to this change by developing various integrated systems for the flood prone areas such as rice-fish and rice-prawn, which also yield higher economic returns than monoculture rice systems.

The annual floods in the delta bring great benefits to farmers and fishers, depositing an estimated 97 million tonnes of silt on farmers’ fields. Large floods are often followed by bumper crop yields and large fish catches, because of the increased abundance of nutrients and silt.

Amongst policy makers in Vietnam there is a constant tension between those who advocate flood protection and those who advocate a strategy consistent with the tradition of song chung voi lut, living in harmony with the flood, through a strategy of diversifying agricultural activities.

Plans to minimise the flood risk, currently receiving investment from the government, involve partial flood protection in the upper Delta and full flood protection in the shallow flooded mid-Delta through the construction of dykes and floodgate systems in order to decrease the area and period of inundation, and to protect settlement and infrastructure areas. The upgrading of the Vinh Te and TraSu-Tri Ton canals, which run from Hau Giang to the Gulf of Thailand, is currently occurring for the purpose of floodwater diversion.

Adapting to saline conditions

Similar to flooding, saltwater intrusion causes environmental risks that are defined and perceived differently by different people with different interests; saltwater intrusion is not perceived as a problem by everyone. During the period of intrusion, agricultural yields are decreased, cropping options for farmers are more limited and freshwater is more scarce. Unexpected saltwater intrusion can also result in crop losses.

However, saltwater intrusion also has positive impacts. Some farmers in the coastal zone of the delta allow salt water to wash onto their fields during the dry season after the harvest of the rain-fed rice crop, in order to raise native shrimp. Farmers living on land with acid sulphate soils allow saline water onto their fields in order to prevent soils from drying and releasing acid. This practice also means the soil is kept soft and doesn’t need to be ploughed. Natural fisheries in the brackish zone (area where fresh and saltwater mix) are highly productive and are an important source of food for local people, particularly smaller-scale farmers and people who do not have access to cultivable land.

Build a ‘fortress’: The World Bank’s response

The World Bank-funded Mekong Delta Water Resources Project is the-Bank’s attempt to respond to the dual goals of reducing environmental risks, and increasing agricultural, particularly rice, production in the delta. The project counts upstream development as an inevitable and external factor, despite that many of the environmentally destructive projects in upstream countries, and in upstream Vietnam, are promoted by the World Bank and its regional affiliate the ADB. In other words, the Mekong Delta Water Resources Project fails to examine the context of environmental risks and development in the Mekong as a whole, but rather considers the problems posed for the delta as technical ‘hitches’ to be solved with purely technical remedies.

This approach ignores the strategies and technologies developed by communities living in the delta. In fact, these communities face serious additional environmental risks from the Bank’s attempt at ‘development’.

Destruction of wild fisheries caused by the construction of flood protection structures and diversion of flood waters, combined with the conversion of brackish water areas to permanent freshwater areas would contribute to the reduction in floodplain and estuarine habitats that are used by fish for feeding and spawning. This concern was raised in the project EIA but was dismissed as ‘insignificant’, and not addressed. The conversion of brackish water areas to permanently freshwater areas would furthermore result in the decline of nypa palm forests.

Reduction of soil fertility will occur as dykes and sluice gates would block the flow of silt, thereby restricting or eliminating silt deposition on agricultural land. In addition, the yearly build up of sediment in channels would have to be continually dredged to keep the channels clear for water transport and irrigation efficiency. The current policy aim of full cost recovery in irrigation operation and maintenance, through agricultural taxes and irrigation fees, would pass these costs directly onto farmers. Farmers would also face additional environmental and economic costs attempting to replace lost soil fertility through the use of agro-chemicals.

In regard to agro-chemical use, the Bank’s Project Appraisal Document states that “[concentrations of permitted pesticides could be increasing with crop intensification, and pesticide contamination remains a major concern in the delta, but many of these have not been systematically measured due to lack of appropriate monitoring and testing equipment.” While the Bank recognises agro- chemical use as a potentially serious environmental problem, the World Bank and other donors active in rural development continue to support the strategy of increased use of high yield variety rice which relies on the use of agro-chemicals

The objective of further increasing rice production, using high yield variety rice and agro-chemicals has failed to deliver economic gains to the small-scale farmers. Farmer indebted- ness has increased due to high input costs and low economic returns. Private traders and primarily state-owned enterprises responsible for official export quotas and rice exports have been the big winners from rice exporting to date.

Furthermore, the potential for worsening resource competition between upstream and downstream communities in the delta as a result of agro-chemical pollution and increased abstraction of water for intensified rice production is high. Downstream communities would be affected by worsening water quality from the disturbance of acid sulphate soils and increased use of agro-chemicals upstream and the decreased availability of water.

The pollution of surface and groundwater quality resulting from these impacts will result in a scarcity of freshwater and consequent increase in water home diseases throughout the affected areas. A decreased availability of household water will result in disproportionate impacts on the health of women due to a decline in sanitary conditions.

The EIA for the Mekong Delta Water Resources Project identifies key environmental impacts but fails to address them. The project will have a disproportionate effect on local communities, negatively affecting those in most need of assistance. The poor and those without access to land who are dependent on local fisheries, non-rice farmers reliant on income from the construction of houses and handicrafts from nypa palms, and those engaged in rice-shrimp cultivation and salt harvesting will be subject to socioeconomic dislocation as a result of the project, as will those forced to resettle or relinquish land to the project.


The increased control and regulation of water resources involving further flood and saltwater intrusion protection also involves the enclosure of a previously open-access resource. Consequently, key aspects of decision making regarding water resources management are now shifting from the on-farm level to centralised, bureaucratic administration, illustrated by the way local farmers must now bring their cropping calendars into accord with the complex operation timetables of irrigation and drainage systems. Investment in massive water resources infrastructure development is occurring in the absence of a framework for effective and participatory water resource use coordination and management at the delta level. The World Bank’s Mekong Delta Water Resources Project allocates a mere one per cent of the total project costs to “strengthening of delta-wide water resources management”.

The current water resource development plans for the Mekong Delta reflect a ‘fortress response’ to perceived environmental risks. They are based on a model of engineering and infrastructural solutions to environmental risks, focusing on the control and modification of the water regime. If implemented, these projects would lock the delta into an inflexible development strategy based on the continued export of rice to an unstable and unpredictable world market.

For generations, local people in the delta have developed adaptive strategies for dealing with the environmental risks of flooding and salinity intrusion. These risks have intensified in recent years due to upstream interventions promoted by mainstream development agencies – in which the World Bank has been an active player. Yet as these problems have intensified farmers in the delta have continued to explore new strategies to deal with environmental change, as evident in the evolution of diverse integrated systems which encourage fanning system- and bio-diversity. The World Bank’s response to these problems, rather than building on traditional strategies, undermines them through the promotion and intensification of rice monoculture.

The Bank’s strategy in the Delta fails to address the origins of environmental threats. Their interventions elsewhere in the Mekong River Basin actually contribute to the exacerbation of these problems yet they, rather than local people, are at the forefront in defining the solutions. The World Bank’s failure to acknowledge the integrity and interconnected nature of ecosystems in the Mekong Basin is evident. Development interventions by the Bank in one part of the basin create problems elsewhere, thus setting in motion the process whereby reactionary and near-sighted mitigatory solutions are proposed.

In light of the environmental risks confronting the Mekong Delta, there needs to be a fundamental rethink of regional development plans. Solutions to environmental threats are not to be found in large-scale, top-down infrastructure and engineering solutions, which present their own environmental risks, but rather through further support and understanding of the traditional adaptive strategies local people have developed, and continue to develop, in response to the challenges posed by environmental change.

Categories: Mekong Utility Watch

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