Water quality management for irrigation in the Mekong River Delta, Vietnam

L.A. TUAN, G.C.L. WYSEURE , L.H. VIET & P.J. HAEST 1 College of Technology, CanTho University, Campus II, Street 3/2, CanTho City, Vietnam 2 Laboratory for Land and Water Management, K.U Leuven, Kasteelpark Arenberg 21, B-3001 Heverlee, Belgium --oOo --ABSTRACT The Mekong River Delta (MD), the most downstream part of the Mekong river, is known as the biggest "rice bowl" of Vietnam. Currently, 2.4 million ha are used for agriculture. During the rainy season part of the Delta is flooded. Along the 600 km-coast, the sea tide strongly influences the water quality by sea water intrusion. In addition, an area of 2-million ha is covered by acid sulfate soils. Also, the MD is very densely populated with intense associated water pollution. The combination of the hydrological regime, sea, soil-type and pollution poses original water quality management problems for irrigation. Along the river and canals in the MD, the water quality parameters are generally related to the use of fertilizers and pesticides in agriculture, of nutrient-rich effluents from aquaculture and animal husbandry and of wastewater from industrial plants and human populations. In the dry season and early rainy period, the polluted water seriously impacts the agricultural cultivation and domestic water supply.