Dams, salt, and the sad fate of Vietnam’s Mekong Delta

Freshwater depletion and salinisation have become critical issues, while nationalism impedes cooperation.

The Mekong Delta, Vietnam’s largest river system, was once a promising destination for migrants from the north of the country during the centuries that shaped the southern region. However, it now suffers from severe drought and saline intrusion.

Originating in the Tibetan Plateau, the Mekong River stretches a distance of nearly 5,000 kilometres, flowing through six countries – China, Myanmar, Thailand, Laos, Cambodia, and Vietnam – and plays a pivotal role in their ecosystems and economies. This is especially true for Vietnam, where the sprawling delta system as the river meets the South China Sea and dominates the southern landscape.

The Mekong River has a self-regulating ecosystem. During the rainy season, abundant water flows from upstream, enriching the delta with silt. In the dry season, water from large lakes such as Tonlé Sap replenishes the river and pushes back seawater intrusion. This unique flow reversal, triggered by monsoon rains, ensures a continuous freshwater supply for downstream countries.

The low-lying delta has undergone centuries of desalinisation and land reclamation, transforming it into Vietnam’s largest granary of rice and aquaculture produce. The area accounts for 17% of the country’s GDP. Additionally, it boasts the country’s most extensive fruit-growing region, known for specialties such as durian, rambutan, and mangosteen, significantly contributing to Vietnam’s economy.

However, over the past decade, freshwater depletion and salinisation have become critical issues, frequently appearing in both domestic and regional media.

This change is believed to be due to the influence of the large-scale hydroelectric system located along the river, which has led to a reversal of the river’s natural flow, previously regulated by the Mekong River-Tonlé Sap Lake mechanism. More than 160 hydropower dams operate on the Mekong River and its tributaries, with hundreds more planned or under construction. While much of the generated energy serves local needs, exports to countries outside the region are increasing.

This year has marked another milestone of drought and saline intrusion in provinces such as Cà Mau and Bến Tre, according to Vietnam’s Deputy Minister of Agriculture and Rural Development Nguyễn Hoàng Hiệp. Hiệp also said that the province has recorded no meaningful rainfall since the beginning of the year. He added: “The intense heat also accelerates water evaporation leading to drought and land subsidence in the fields.” 

A canal project in Cambodia, expected to begin construction by the end of this year, has raised significant concerns on the Vietnamese side about the potential further disruption of the ecosystem and local livelihoods. Nationalism and individual interests exacerbate the challenges of managing this shared resource among the six countries, leaving existing mechanisms such as the Mekong River Commission (MRC) with limited influence. This, in turn, contributes to the growing uncertainty surrounding the Mekong Delta’s future, as evidenced by recent struggles to secure freshwater sources during dry seasons and the loss of thousands of hectares of crops in Vietnam.

On 5 May, Vietnam raised concerns about the Cambodian project’s impacts on the Mekong Delta and urged Cambodia to collaborate with Vietnam and other MRC countries to assess the effect of the the canal on water resources. Experts at the Vietnam National Mekong Committee had recommended that Hanoi seek a postponement of the project from Cambodia to allow for additional talks, warning the planned canal might accelerate the saltwater intrusion situation in the downstream of the Hậu River.

However, Cambodia’s response indicates that they will not negotiate with Vietnam over the project and will proceed with construction of the canal, pointing out that Vietnam has heavily invested in dam construction, which have negative consequences for Cambodia.

The cost of this stand-off is being felt most by the people living on the delta.

By Buu Nguyen – The interpreter – May 14, 2024