Parts of the Mekong Delta region in southern Vietnam are suffering from land subsidence at the alarming rate of up to four centimeters per year, due largely to excessive groundwater extraction, experts have said.
The findings are a result of the ongoing ‘Rise and Fall’ program which aims to enhance the capability of individuals and organizations to develop sustainable strategies for dealing with land issues in the increasingly urbanized Mekong Delta region.
The program, scheduled to run between 2014 and 2018, is jointly carried out by Vietnam’s Can Tho University and the Netherlands’ Utrecht University, with funding from the Netherlands Organization for Scientific Research (NWO).
Experts on the program held a seminar in Can Tho City on Tuesday to announce their preliminary findings of land subsidence in the delta.
Prof. Dr. Piet Hoekstra, CEO of ‘Rise and Fall’, attributed the swift transformation in the Mekong Delta to rapid urbanization and land usage conversion, leading to increasing demands on the water supply.
To cope with the demand, more and more large-scale groundwater extraction projects have sprung up in the area, threatening to exhaust the source of freshwater, Dr. Hoekstra said.
Subsidence rates in Vietnam’s Mekong Delta have been measured at between 20 and 40 millimeters per year, which easily exceeds the current global sea level rise of only 3-4 millimeters per year, according to Ky Quang Vinh, chief of office at Can Tho City’s Office for Climate Change.
Land subsidence in the delta is therefore even more alarming than the threat of rising sea levels, experts warned at Tuesday’s seminar.
According to Tran Van Thanh, deputy director of Soc Trang Province’s Department of Natural Resources and Environment, many local waterways have run dry due to the extraction of groundwater over extensive periods of time for aquaculture activities.
Groundwater levels have dropped an average of between 0.3 and 0.8 meters per year, Thanh said, citing the results of studies by Soc Trang authorities.
With over 50 percent of the delta’s surface elevated by less than one meter, this poses a real threat to residents, and increases the risk of flood and salinization.
A recent report by Ca Mau Province’s Department of Agriculture and Rural Development revealed that the province was spending VND billions every year on counter-subsidence efforts.
Over the past five years, water levels at the opening of the local Ganh Hao River have risen by 73 centimeters.
Should the rise persist at the same alarming rate, it is estimated that around 90,000 hectares of Ca Mau’s agricultural land, which make up one sixth of its total area, will become submerged in the near future.
Should no measures be imposed to limit or stop extraction activities, the entire Ca Mau Province may well disappear in the next few decades, experts from the Norwegian Geotechnical Institute warned.