Vietnam's Mekong Delta threatened by rising sea levels • FRANCE 24 English

Key Concepts

• Salinization: The process by which salt water intrudes into freshwater systems, rendering land infertile.
• Climate Change: The overarching driver of rising sea levels and water temperatures.
• Aquaculture: The farming of aquatic organisms, presented as an adaptation strategy.
• Upstream Dams: Infrastructure projects impacting river flow and sediment transport.
• Meong Delta: A critical agricultural region in southern Vietnam facing significant environmental challenges.

Impact of Climate Change on Agriculture in Southern Vietnam

A farmer in southern Vietnam is experiencing a steady decline in rice yields over the past five years, with a 40% loss last year alone. The primary cause identified is the intrusion of saltwater into rice paddies, which damages rice plants and grains, leading to crop destruction and infertile land. This salinization is a direct consequence of rising sea levels, which are increasing by 3 to 5 mm per year in the Meong Delta. The flat topography of the delta facilitates this saltwater seepage inland. The Meong Delta is home to 18 to 20 million people who depend on it for their livelihoods.

Threats to Fisheries and Research Efforts

Beyond rice, fish populations are also at risk. A university in southern Vietnam, in collaboration with a French agricultural research institute, is studying these changes. Their research involves capturing fish in waters with varying salinities to observe their adaptations and changes in refinement. This methodology combines laboratory research with fieldwork.

Scientists are also conducting regular boat trips to a small island to investigate rising water temperatures, another consequence of the climate crisis. They are concerned that warmer water is contributing to the extinction of certain fish species.

Focus on Pangasius Catfish

A specific area of research is the pangasius catfish, the most recognizable fish in the delta and a significant contributor to Vietnam's economy. In 2024, Vietnam produced approximately 1.6 million tons of catfish, accounting for 42% of the global catch. The highest acceptable temperature range for pangasius is 35° centigrade. Monitoring of pangasius pond water temperatures in Vietnam and Cambodia over the past two years has revealed that during summer, temperatures can reach up to 37° centigrade, exceeding the maximum tolerance level by 2°.

Adaptation Strategies: Sustainable Aquaculture

In response to rising sea temperatures and the inability to grow rice, many Meong Delta residents are adopting a new form of aquaculture. In Camal Province, vast aquaculture farms now occupy over 300,000 hectares of land previously used for rice cultivation. These farms utilize a sustainable, self-sustaining ecosystem where algae help cool the water, and fish and shrimp are raised together.

Integrated Aquaculture System

The process involves recovering waste from shrimp ponds, which contains nutrients, along with the water. This nutrient-rich water is then pumped into fish tanks. Algae within these tanks purify the water, making it clear again.

A former rice farmer attests to the success of aquaculture, stating it provides a stable income higher than rice farming and is less susceptible to climate change impacts.

Compounding Crises: Freshwater Shortage and Upstream Dams

The Meong Delta is facing two major crises: rising sea levels and a worsening shortage of fresh water. These issues are exacerbated by large hydroelectric dams constructed upstream, closer to the river's source. While not explicitly named, the expert points towards China as the location of these dams.

Impact of Upstream Dams

These dams significantly alter the river's natural flow and reduce the amount of sediment reaching the lower delta. This reduction in sediment leads to decreased fertility of farmland downstream.

Conclusion: Environmental Emergency

Scientists emphasize that saving the Meong Delta is an environmental emergency. The livelihoods of over 60 million people across Asia, who depend directly on the Meong River, are at stake.