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Vietnam’s Mekong Delta Study misses key impacts from upstream dams
Hoang Duong

Floating market in Vietnam's Mekong Delta. Photo: Hoang Duong Floating market in Vietnam's Mekong Delta. Photo: Hoang Duong

The Mekong Delta Study (MDS) initiated by the Government of Vietnam looked at the consequences of Mekong mainstream hydropower with the goal to protect Vietnam’s Mekong Delta, home to 20 million people and producing more than 50% of the country’s rice, vegetables and fruits.
But the MDS and its findings have come under criticism for being flawed in its process, weak in its social assessments, and failing to provide meaningful integration of local communities’ livelihoods concerns in the delta areas.
Costing US$4.3 million, the two-year MDS was initiated in 2013 by the Government of Vietnam and conducted by Vietnam National Mekong Commission (VNMC) along with international partners including the Danish Hydraulic Institute (Denmark) and HDR, environmental consultants; the International Center for Environmental Management (ICEM); and others. The study covers 16.5 million ha including the flood plains in Cambodia (from Kratie to Phnom Penh), the Great Lake or Tonle Sap system, Cambodia’s Delta (from Phnom Penh to the Vietnam border), and the Mekong Delta in Vietnam (from the Vietnam border to the East Sea). The study went through four phases: Inception; Baseline Studies; Impact Assessment; and Avoidance, Enhancement, and Mitigation.
In December 2015, the third phase was finished and the VNMC held an event to gather comments and feedback about the “Impact Assessment Report” (IAR). The final IAR report was submitted to the Council of the Mekong River Commission (MRC) at the end of 2015.
What did the study look at?
As the last country receiving the flows of the Mekong River, upstream construction and interventions are expected to cause severe impacts to Vietnam and its delta areas. The Mekong Delta is home to 20 million people and produces more than 50% of the country’s rice and fruits. It’s extraordinary diversity and productivity of rice, fish, fruits and vegetables feeds was estimated in 2011 to support 18.6 million people in the delta or about 22% of the country’s population, and a further 92.5 million people in Vietnam in 2014.
Vietnam therefore has a big stake in a comprehensive, scientific understanding of the impacts on the delta from the large dams planned on the Mekong River. The main goal of the MDS study reflects this: “to provide a fully understanding about impacts of proposed constructions on the Mekong River to natural environment and people, economy, society, and livelihoods of millions of people in the Mekong Delta”.1
The MDS aimed to understand the territorial morphology and geography along the Mekong and in the context of rapid infrastructure development especially large dams and water diversion projects on the Mekong River. The study looked at how places in the scope of the study would change under different scenarios using criteria such as flow regime, sediment loading, water quality, and longitudinal connectivity (barrier effects).
The MDS looked at three separate scenarios and their ecological impacts:
Scenario 1: The cascade of eleven dams on the mainstream of the Mekong River.
Scenario 2: The cascade plus dams in the main tributaries; and,
Scenario 3: The cascade and water diversion schemes in Thailand and Cambodia.
Key findings
According to the study, the main irreversible impacts from the projected scenario if the cascade of eleven dams are built are as follows:
Study methods criticised: Too much technical modelling, too little local perspectives
The study has come under criticism for its over-dependence on modelling scenarios while paying little attention to social considerations including local communities’ perspectives and concerns.
While it calculates the losses of sediment, fishery, and agriculture, the impact on livelihoods is not considered significant according to the study. For example, the study’s section on livelihood, under scenarios 1, 2 and 3 concluded that the “The level of dependency on water related resources [would have] low adverse effect on annual average consumption of fish per household (HH)”. (Table 4.6-1 Livelihood impact summary by indicators. Page 51. Impact Assessment Methods and Results – Summary Version).
Given the massive disturbances to river ecosystems from large dams, this seems a low estimate of the potential impacts on fisheries from an entire cascade of dams on the mainstream Mekong River. The study has also come under criticism from civil society groups for selecting too few sampling sites that were not wholly representative of the fisheries sector in investigating the impacts on Mekong fisheries.
Similarly the study concluded that the impacts for agriculture for all 3 scenarios has “no effect” and “low adverse effect”. But in 2015, saline intrusion has already seriously threatened 620,000 hectares of rice fields in Vietnam’s coastal provinces of Bac Lieu, Soc Trang, Tra Vinh, and Tien Giang. Greater seawater intrusion into the delta is already affecting both crops and livelihoods and many farmers are trying to switch from planting rice to shrimp farming.
MDS process: Lacking local participation
The study has come under criticism for lacking community participation and public consultation. The limited study process meant it did not get a complete understanding of the issues related to people’s livelihoods in the delta. As such, many experts and non-governmental groups in Vietnam have urged that the study be halted and and re-conducted for more “responsible conclusion”.
Failing to protect the Mekong Delta
In October 2015, at the Greater Mekong Forum on Water, Food, and Energy (GMF 2015) in Phnom Penh, Cambodia, the VNMC held a session with the MDS consultants to present the Mekong Delta Study. This was followed by two national consultations: Impact Assessment Report on October 28 in Hanoi, and October 30 in Ho Chi Minh City in which academic groups and others participated to voice perspectives about the MDS.
Thus the concerned groups and public were given two months for review and comments of the report before it was released in December 2015. But even then, many of their critical comments of the MDS were not taken into account. A number of key criticisms of the report made in these forums were edited out of the final released report.
This is quite similar to the public consultation process Procedures for Notification, Prior Consultation and Agreement (PNPCA) for the Xayaburi and Don Sahong projects, both mainstream Mekong River dams. The process goes through with public consultations (albeit not fully adequate). But finally, local concerns and critical perspectives are ignored, and the process is just used to give a go-ahead to continued dam construction.
The MDS has not provided any voice for local communities, and has made weak assessments that significantly underestimate the potential losses of fish and agriculture to the delta areas and its communities.
Ultimately, the MDS has failed in its main stated goal: it cannot protect the delta and its inhabitants from the potential massive losses that would occur from the building of large dams and water diversion projects in the Mekong River.
The article was originally published on the website of (
Republished with permission