SOURCE: VOA News
DATE: February 16, 2019
SNIP: Nearly the entire Mekong Delta in Vietnam — an area that helps feed about 200 million people — will sink underwater by the year 2100 at current rates, a new study predicts.
The delta, which is home to almost 18 million people and produces half of Vietnam’s food, faces this potential humanitarian crisis largely because the heavy extraction of groundwater is causing land to sink as sea levels simultaneously rise, the study found.
When combined with rates of sea-level increase because of climate change, they found that no matter what action was taken the vast low-lying delta plain will be lost.
Fueled by Vietnam’s transition to a market-based economy in 1986, groundwater extraction had accelerated from practically nothing 30 years ago to the 2.5 million cubic liters now sucked out of the delta’s water table every day.
The loss of water … reduced pressure in the underlying geology, causing the delta to sink.
At the same time, he said, the sea level is rising at a rate of about 3 to 4 millimeters per year.
Loss of naturally replenishing sediment is another critical factor in the sinking of the delta.
Upstream dams on the Mekong, which flows more than 4,000 kilometers from the Tibetan plateau in China through Laos and Cambodia before discharging through the delta, had led to about a 40 percent loss in sediment flow, he said.
A 2018 study by the Mekong River Commission found a catastrophic 97 percent of sediment flow to the delta would be lost by 2040 if all planned dams on the Mekong and its tributaries go ahead.