Change of water resource condition during the flood season in the Mekong River Delta of Vietnam due to the impact of upstream Mekong River dams

Abstract

The Mekong River Delta of Vietnam is affected by floods from the Mekong River Basin with the annual flood prone area which varies from 1-2 million ha; the flood peak at Tan Chau - the upstream station in Vietnam - varies from 2.4-5.1 m. Big floods (flood peak >4.5 m at Tan Chau) often cause many damages for agricultural production, infrastructure, people and properties. However, floods may also bring a lot of benefits to the delta such as alluvial sediment to fertilise the soil, fishery resources, water quality improvement, and soil reclamation. The existing crops like Winter - Spring and Summer - Autumn rice crops all evade from the flooding period to avoid the damages and exploit the advantages of flood. The hydropower development at the upstream of Mekong River will cause a large change to the flood conditions in the delta. This paper presents the change of annual flood due to the upstream hydropower development scenarios and recommendations to change the cropping pattern in the delta to adapt with the hydrological change.