Map of the Mekong Delta in Vietnam and Cambodia. A narrow trough of theancient South China Sea covered land north of Phnom Penh creating the deltalowlands. Map courtesy of Mic Greenberg. (111)The population began to expand after French colonists set up a series of canals in the 1800’s, in an attempt to partially drain the delta. After the canals were installed, dikes and levees followed. Once people had more control of the water, they could make it work for them. Today, the Mekong Delta is a leading exporter of rice, shrimp, and other seafood.
But the productivity of the delta may not last forever, according to the researchers. In fact, delta farmers and other residents are already experiencing problems.
“The hydrological balance between the South China Sea and the Mekong River is shifting,” says Lois Wright Morton, professor emeritus in the Department of Sociology at Iowa State and co-author of the article.
“New dam-building upstream across the main stem of the Mekong River in China and Laos, along with recent droughts, have reduced the river’s freshwater flows during the monsoon season. Further, rising sea levels from a changing climate is pushing seawater upriver into the branches and main stem of the Mekong River and Delta during the dry seasons, causing serious saltwater intrusions. The deposition of rich sediments during the monsoon seasons is important for agricultural production and has been significantly reduced.”
The researchers point out that the Mekong Delta is not alone in trying to balance environmental challenges with the need to support increased food production and a growing population. Other major deltas, including the Mississippi, are experiencing loss of wetlands, land subsidence, reduced sedimentation on coastal wetlands, poor water quality, and excess agricultural nutrients and other pollutants.
“Historical perspectives, new science and technologies, and public and political efforts are critical if the deltas of the present and future are to ensure an environment habitable for human well-being and strong agricultural productivity, while strategically conserving wetland ecologies,” Olson says.
The article, “Polders, dikes, canals, rice, and aquaculture in the Mekong Delta,” is published in theJournal of Soil and Water Conservation[DOI: 10.2489/jswc.73.4.83A].
