Policy should address the drivers of decline, not just its symptoms

said Matt Kondolph, co-lead author of the study, and professor of landscape architecture and environmental planning at the University of California. Berkeley.

“The Mekong Delta is truly exceptional in terms of agricultural economic value and regional importance for food security and livelihoods,” said study co-lead author Raphael Schmidt, a senior researcher at Stanford University. “Without rapid action, deltas and their livelihoods could become victims of global and regional environmental changes.”

On its journey from the towering peaks of Tibet to the sea, the Mekong River collects sediment from the eroded highlands of China, Myanmar, Laos, Cambodia, Thailand and Vietnam. Nutrient-rich sediments accumulated in the Mekong Delta and enabled the Lower Mekong region to produce up to 10% of all rice traded internationally. It has also fed fisheries that feed tens of millions of people. Like any river delta, the Mekong Delta can exist only if it receives a constant supply of sediment from the upstream basin, and if the flow of water can spread these sediments over the lower surface of the delta to build up land at an equal or higher rate. of global sea level rise.

Hungry for renewable energy, the basin countries have built many hydroelectric dams that prevent fish migrations, trap sediment, and reduce downstream flows. If all the planned dams were built, they would hold 96% of the sediments that reached the delta. In addition, the sediment supply from tropical cyclones, which provides about 32% of the suspended sediment load that reaches the deltas, decreases as cyclone tracks move north.

The sediments that manage to reach the bottom of the Mekong River are mined from the sands used in construction and land reclamation. Excessive groundwater pumping and tall dams built to control flooding and enable high-intensity farming exacerbate the problem.

To slow and reverse the damage, researchers recommend that policymakers:

• Design dams to allow better sediment passage, and place them strategically to reduce their downstream impacts, or, if possible, replace them with wind and solar farms.
• Strictly regulate sediment extraction and reduce the use of Mekong sand through sustainable building materials and recycling.
• Allow flood water to spread over the delta and deposit its sediments
• Reducing groundwater pumping in the Mekong Delta
• Reassessing intensive agriculture in the Mekong Delta for sustainability.
• Implementation of natural solutions for large-scale coastal protection along the coast of the delta

According to the researchers, most Delta rehabilitation efforts have involved individual countries to address isolated engineering challenges and propose solutions at the local level. Achieving meaningful progress will require coordination between countries, development agencies, development banks, and other civil and private actors, the researchers wrote.

“We’re seeing signs that governments and non-state actors are starting to work together on these issues,” Schmidt said. “We hope our comment raises the topic on the regional policy agenda, advances conservation in the basin and serves as a wake-up call to address the major drivers of global land loss for the system.”

Story source:

Materials offered by Stanford Woods Institute for the Environment. Original by Rob Jordan. Note: Content can be modified according to style and length.