Every year, the southern region loses 300 hectares of land because of subsidence and landslides. The Mekong Delta, for example, is sinking faster than predicted.
The landslides in the Delta have been described as ‘extremely serious’. Deputy Minister of Agriculture and Rural Development Hoang Van Thang reported that there are 49 landslide spots with total length of 266 kilometers. In some places, the sea has entered 80 meters into the mainland.
The eastern and western parts of Ca Mau and Kien Giang provinces suffer most from erosion. More seriously, the sedimentation in river systems has been lower than erosion since 2000.
According to the Mekong River Committee, the volume of sediment in Mekong Delta will decrease by 67 percent by 2020. The countries on the upper course of Mekong have built so many hydropower plants and water reservoirs (two large reservoirs built by China alone have capacity of 22 billion cubic meters). Silt is retained at the reservoirs and cannot reach Vietnam’s Mekong Delta.
The committee has drawn up a scenario that by 2040 if all hydropower projects arise on Mekong mainstream, the volume of silt that can reach Vietnam will fall to 3 percent.
Scientists have warned about the disintegration of Mekong Delta. In the past, it was consolidated by 145 million tons of sediment. But now, it receives only 40 million tons, and sediment has been taken away by hydropower plants.
The overexploitation of sand is also a danger to Mekong Delta. The International Union for Conservation of Nature (IUCN) estimates that of 40 million tons of silt and sludge, Cambodia exploits 30 million, and Vietnam 10 million tons.
In July 2013, the Norwegian Institute of Geotechnics found that the Mekong Delta subsided 19 – 28 mm per annum, caused by the soft ground and excessive underground water exploitation. If combined with rising sea levels, the Mekong Delta region is likely to sink faster than expected.
In 2016, Vietnam released a prediction that about 35 percent of Mekong Delta’s area may be inundated under water by 2100. However, with the current subsidence rate of 1.5-2 cm per annum and rising sea water levels, the scenario may come sooner than expected.
MARD Minister Nguyen Xuan Cuong said Vietnam needs to adjust its development policy to fit the new conditions. In the past, rice production was the top priority, while seafood and fruit were in the second and third positions. But in current conditions, seafood must be the top priority, and rice the third.