05. Assessment of drought level by using the indicator of flow deficiency in the Mekong delta

Abstract

The Mekong river delta region comprises of 13 provinces and cities with a total area of ​​about 40,600 km². The population in the region is approximately 21.49 million, accounting for nearly 22 % of the Vietnamese population. It is a strategically important region of particular political, economic, cultural and social importance. It is the largest rice field in Viet Nam and also the area that provides a large amount of aquatic, seafood and agricultural products for national consumption and exports. However, during the dry season, the low flow from the upstream combined with rising sea tide significantly causes seawater intrusion into the farmland, which results in difficulties in the livelihood and production of local people. Almost every year, the Mekong delta region is also severely affected by a strong magnitude of drought. From 2013 to 2020, the Mekong delta region is greatly affected by drought in a large area, which continues for a long time. Recently, there have been many studies on the causes of drought and factors affecting drought and hydrology, such as the deficiency of upstream flow and the low water level, etc. This article presents the research results on the deficiency index of flow at hydrological stations in the lower Mekong delta with the results of drought classification according to 05 levels as normal, medium, light, severe and very severe drought for the months of the dry season. Conducting drought classification as a basis for research to provide more classification criteria for disaster risk assessment in the downstream area.