In early June the GEF International Waters Fund has confirmed a USD 15 million new funding to boost efforts in support of the Mekong Delta aquifer. It aims at improving the Delta’s groundwater system that is severely overexploited due to high demand for water resources from the rapidly increasing population and rapid economic development.

The lower section of the Mekong River Basin is underlain by a major transboundary aquifer system shared by Cambodia and Viet Nam. This transboundary aquifer system (TBA) connects two ecosystems of global environmental significance and socio-economic importance:  i) the Tonle Sap area and the ii) the Mekong Delta, and includes some major urban areas, including Phnom Penh and Ho Chi Minh city.

The whole area is approximately 200 000 km² with about 63 per cent lying within Cambodian territory. The Tonle Sap, the largest lake in the peninsular Indochina, is hydraulically connected to the Mekong River, and serves as a natural regulating reservoir ensuring adequate groundwater recharge to the aquifer.

The groundwater resources in this TBA have a considerable impact on human livelihoods and socio-economic development.

Groundwater strongly supports the agricultural sector in Cambodia, which accounts for about a quarter of the country’s GDP and employing approximately 37 percent of its labour force. For these reasons, the aquifer is heavily exploited for irrigation and water supply. The annual groundwater extraction rate throughout the TBA is estimated to be about 800–900 million m³/year.

The integrity of ecosystem services is critical both in terms of biodiversity and of the sustainability of a range of natural resources and products available to both urban and rural populations. The effects of surface and groundwater interactions nourish large tracts of forests and wetlands, which produce building materials, medicines and food, and provide habitats to thousands of species of plants and animals.

Naturally, groundwater interacts with areas of low-lying land where permanent wetlands tend to develop. These wetlands provide habitat for fish breeding, buffer flood events by absorbing huge quantities of excess water and offer natural water cleansing functions. In addition, groundwater sustains wetlands during the dry season: when groundwater levels drop below the historic norms, wetlands can dry out.

Unfortunately, there are a wide array of challenges facing sustainability of the groundwater system and its quality, ranging from overexploitation of the groundwater resource to support economic activity, occurrence of arsenic, deforestation, climate change and upstream hydropower development.

One of the project’s main objectives is to establish cooperative management frameworks for this major transboundary aquifer embracing the whole Mekong delta and extending upstream in Cambodia. This is of critical importance because of the region’s high dependence on water resources, and vulnerability to climate-related hazards (floods and droughts, sea level rise).

The project will also begin to address gaps in data and knowledge and promote a proper and shared understanding of the regional groundwater flow regimes, especially with regard to the up-gradient recharge zones within the Cambodian territory. 

So far, two major barriers have hindered the implementation of cooperative groundwater resources management strategies and plans: i) the different levels of understanding that the two countries have of the TBA system, and; ii) the differences in groundwater management policies in Cambodia and Viet Nam that increase the difficulty of reaching a bilateral agreement for sustainable TBA development.

The proposed project - targeting the main aquifer of the Lower Mekong Basin shared by Viet Nam and Cambodia - will complement the recently approved GEF-World Bank project: Mekong Delta Integrated Climate Resilience and Sustainable Livelihoods, and its related IDA loan, and other ongoing initiatives, by:

• Addressing for the first time the groundwater component of the hydrologic system of the Lower Mekong in its entirety, including the critical upstream Cambodian section with its groundwater related freshwater ecosystems and recharge areas controlling subsurface water flow to the delta;
• Reinforcing the countries’ institutional capacity in groundwater governance;
• Creating the enabling environment and policy frameworks for transboundary cooperation in the management of the shared aquifer resources and dependent ecosystems.

In Cambodia, the project will be implemented under the combined leadership of the Ministry of Environment (MoE), Ministry of Agriculture, Forestry and Fisheries (MAFF) and the Ministry of Water Resources and Meteorology (MoWRAM) as well as other development partners in the sector as relevant.

Learn more about FAO-GEF and GEF here and here.