Water balance for agriculture production in the dry seasons of the Mekong river delta in Vietnam

The Vietnamese Mekong river delta (MD) is the largest wetland region in the southernmost part of the Mekong river basin and connects more than 700 km of coastal line to the East Sea and the Gulf of Thailand (Fig. 1). The Delta is four million ha in size (12% of total natural land of Vietnam) and hosts more than 18 million inhabitants (about 22% of the entire country’s population in 2009). For more than 300 years, the local people have lived close to rivers and streams to facilitate the domestic use of water, such as for agricultural cultivation, fishery, and river transportation. Thus, any change in the water source affects their activities and the ecosystem of the area. The MD is recognized as the largest agriculture and aquaculture production region of Vietnam. The delta supplies more than 53% of the nation’s staple food, rice (Fig. 2), 65% of the total fish production, and 75% of the tropical fruit trees. Further, rice production is considered to be the main economic sector, which occupies more than 60% of the labour force in the MD.