Polders, dikes, canals, rice, and aquaculture in the Mekong Delta

Abstract

A quarter of a century ago, the Mekong Delta of southern Vietnam and southeast Cambodia was a vast swamp of freshwater and saltwater marshes, with half the region under water for many months of the year (Taylor 2014). The warm, moist prevailing winds of the southwest monsoon bring continuous rain May through October, high rates of runoff, and extensive flooding throughout the delta. Much of the low-lying alluvial plain where the Mekong River and its distributary, the Bassac River, flow south into the South China Sea is barely 2 to 3 m (6 to 10 ft) above sea level (figure 1). Seawater incursions from tides and wave action bring salt water into coastal areas and upriver lands adjacent to river distributaries that outlet into the Gulf of Thailand and the South China Sea. Colonial geographers and surveyors of the 1800s reported the Mekong Delta as an inhospitable, underpopulated land with salty-acidic soils, a scarcity of fresh water during the dry season, and indigenous people infected by malaria (Taylor 2014). The Dutch dike strategy of dikes and polders initiated by colonial governments in the 1930s pumped fresh water into rice ( Oryza sativa L.) fields and was intended to protect the soil…