This is the first bi-lateral GEF project between Lao PDR and Viet Nam focused on shared rivers of Ma and Neun/Ca. These two transboundary rivers are adjacent, with similar-sized basins with similar characteristics and water and environmental management challenges. Key challenges include hydropower reservoirs causing significant changes to flows in tributaries of both basins; deforestation and changes to forest cover impacting flows and sediment loads; agricultural expansion; increasing water withdrawals associated with demographic growth and rapid economic development affecting environmental flows; and emergency releases from dams during extreme water events contributing to flooding. Climate change is expected to be one of the biggest drivers of hydrological transformation, affecting rainfall, temperature, evaporation and water quality.

Future water scenarios show that flows through the system will tend to increase sharply, especially towards the end of the century. The greatest increase will be in wet season flows, signalling the possibility of major floods severely impacting economic development. Continuing development in the two basins, combined with climate change, is affecting the coastal areas of the South China Sea due to the degradation of surface and shallow marine waters quality, increasing frequency and magnitude of floods and droughts, seawater intrusion in coastal aquifers caused by groundwater over-extraction and sea-level rise. The emerging situation is posing serious threats to water supply for the rapidly expanding coastal populations. and to coastal habitats, such as mangroves, wetlands, fish refugia, and livelihoods (e.g. fisheries).