An environment staff in Ho Chi Minh City tries to unclog a drain hole as heavy rains flooded a street in Binh Tan District, October 2018. Photo by VnExpress.
A survey of 339 locations in the Mekong Delta and Ho Chi Minh City has found 306 have sunk by 0.1 to 81.4 cm over the last decade. 19 of the sink-spots are in Saigon, Nguyen Minh Khuyen, deputy head of the Department of Water Resources Management under the Ministry of Natural Resources and Environment, said at a conference on land subsidence in Can Tho.
An Lac Ward in Saigon's Binh Tan District has sunk the most over the decade at 81.4 cm. In the Mekong Delta, Can Tho City, Soc Trang and Bac Lieu Provinces have sunk the most, by between 52.4 and 62.6 cm, said Khuyen.
The total area of subsided land is approximately 24,000 square kilometers, or about 91 percent of all areas surveyed, he added.
The subsidence was caused by a combination of both natural and human activities, including excessive groundwater extraction and impacts of urban construction, infrastructure and traffic.
About 9,650 bore wells are functional in surveyed areas, with a total capacity of 1.97 million cubic meters per day. 1,900 of them are in Saigon, with a total capacity of 520,000 cubic meters per day. There were also over a million smaller wells for residential use, with a total capacity of 840,000 cubic meters per day, he added.
Multiple studies over the last decade have warned that the Mekong Delta, which is spread over 40,577 square kilometers and world's third largest such region, is slowly sinking and might disappear within the course of a century as sea levels rise.
Climate Central, a U.S.-based nonprofit news organization that analyzes and reports on climate science, has controversially assessed that most of southern Vietnam, including the Mekong Delta and the nation's economic hub, Saigon, could be flooded by 2050.
In September, a group of Dutch scientists from Utrecht University said the Vietnam's Mekong Delta has an "extremely low mean elevation" of just around 0.8 meters above sea level, which is dramatically lower than the 2.6 meters assumed earlier from NASA's Shuttle Radar Topography Missions data. It estimated that at its current rate of subsidence the delta could be under 0.8 meters the sea within 57 years, requiring over 12 million people to relocate.
The delta’s flooding areas would increase from 1.9 million hectares in 2000 to 3.2 million hectares in 2050, Vietnam’s Southern Institution for Water Resources Planning has estimated. That includes most roads and several localities in the region.
Do Duc Dung, head of the institution, said tighter groundwater extraction management, and reduced use of groundwater sources for crops and animal husbandry are among potential solutions to alleviate the problem of land subsidence in the Mekong Delta.