Dealing with saline water in Mekong delta

Due to land subsidence, climate change and changes in the water system, the salt content of the shallow groundwater in the Mekong Delta in Vietnam is increasing. The salty groundwater significantly reduces agricultural production and damages fruit trees, resulting in loss of income for farmers and reduced availability of food in the region. It also requires more fresh water for irrigation.

Subsurface fresh water storage/control is a widely applied technique, but not yet in the Mekong Delta in Vietnam. Our solution is to control the salty groundwater through optimised (subsurface) drainage. The principle is that the layer of subsurface drains and/or ditches controls salt seepage and the salty groundwater.

The groundwater is then discharged into channels and rivers. This system helps form a freshwater lens in the topsoil during the rainy season and maintain it during the dry season (when irrigation is available), resulting in increased food production and reduced water demand.

This approach makes land suitable for agricultural production again, increasing both food production and farmers’ incomes in the region. Part of the solution is also that abandoned aquaculture ponds are made suitable for agricultural production.

The concept itself is widely applied in the Netherlands. In Wieringermeer salt seepage and salty groundwater is controlled by deep drains. Witteveen+Bos successfully applied and introduced this system for land reclamations in Jakarta Bay to improve the geohydrological conditions of a golf course. (Improved) subsurface drainage, however, does not exist in Vietnam and is an innovative solution for the problems in this delta.

Witteveen+Bos won an award for this drainage concept. The award formed part of the Agro-water Contest in the Mekong Delta. With this award, Witteveen+Bos received a budget to further develop the idea and seek funding for its implementation in Vietnam. To achieve this, we are working together with Deltares, Barth Drainage and MWI from Vietnam. The Agro-water Contest is an initiative of the Royal Netherlands Embassy in Hanoi.

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