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How is Vietnam’s Mekong Delta adapting to a changing climate?
In the floodplains of the upper Mekong Delta in southern Vietnam, the regular seasonal monsoon floods, lasting from late July until November, are replenishing the soil, rejuvenating the river ecosystems, and allowing farmers like Nguyen Van Khen to boost incomes through flood-based agriculture.
But floods could quickly turn into a problem if they get stronger than expected or go off cycle. Heavy flooding could wipe out farming areas overnight.
In the upper Mekong Delta, such irregularity comes in more often, prompting farmers to rethink their livelihood strategy. This is predicted to get worse with climate change.
During a recent trip to the Mekong Delta, we witnessed how a World Bank-financed project has significantly strengthened farmers’ ability to cope with the new reality. Embankments supported by the project help a large farming area withstand the floods while capturing the rich floodwater to nourish the crop.
First, it’s sinking, on average of about 1.1 centimeters per year, due to excessive groundwater extraction, sand mining, and reduced sediment deposition. This very threat to the Mekong Delta’s existence is compounded by sea level rise.
A conservative estimate from our Vietnam’s Country Climate and Development Report warns that almost half of the delta could be submerged if sea level rose by 75–100 centimeters, relative to 1980–1999 levels.
Second, it’s facing intense weather fluctuations.
Around the delta, the sea encroaches, carrying saltwater inland through its myriad of waterways. In better days, the Mekong River surged through the lower river basin, washing the salinity back out to sea. More recently the reduced river flow in the dry season has accelerated saline intrusion, a trend accentuated by droughts, as in 2020.
It’s not just wet and dry seasons. Extreme droughts and floods strike more often, with greater intensity. When Mother Nature goes off balance, the farmers bear most of the brunt. For example, saltwater can destroy an orchard worth several years of farmers’ investment and push them into bankruptcy.
Added to the challenge is the degradation of the environment due to many years of resource-intensive and unsustainable farming practices.
In 2017, the Government of Vietnam passed a much-needed resolution that embraces a new thinking – “actively living with nature.” With that, the development trajectory of the Mekong Delta has shifted. But what exactly does “actively living with nature” mean?
In the upper delta, local people used to divert the floodwater with dikes so that farmers could grow rice all year round. But this model is no longer economically profitable or ecologically sustainable.
As our project has proven, farmers can work with floodwater, instead of against it. During the flooding season, they can let water inundate their fields, turning them into the perfect setting for aquaculture. These aquatic resources have proven to bring in higher incomes than the third-crop rice. When the water recedes in the dry season, fish excreta and alluvium enrich the soil, making it fertile for growing the next crop.
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