By Vietnam Net Bridge
Ho Chi Minh City, Vietnam, June 29, 2017
The Ministry of Agriculture and Rural Development’s (MARD) report on the cause of landslides in the Mekong Delta has pointed out eight reasons, but scientists say the report is too vague, making it difficult to find reasonable solutions.
The eight reasons are: imbalance of mud and sand; weak geology in the landslide areas; riverside and coastal construction works; rising sea water levels; sand overexploitation; waterway transport; underground water overexploitation; and changes in current.
Ho Long Phi, director of the Water Management & Climate Change Center, an arm of the HCMC National University, said the reasons cited by MARD do not show the real causes of landslides in every area.
“The causes of landslides are different in different areas and it is necessary to identify the specific reasons to find the best solutions,” Phi said. “Riverside erosion is different from seaside erosion.”
Phi said that the imbalance in mud and sand has been occurring for a long time and has not had a direct impact.
He agrees with MARD that landslides have been caused by mud and sand overexploitation. This has caused deep holes which have deepened the riverbed abnormally.
As a result, big volumes of mud and sand need to be replenished, leading to landslides on a large scale
Other mechanical factors such as the construction of multi-story buildings, loading increases on riversides and coastal areas, strong sea waves and high-speed boats all have also been cited as direct reasons behind the large-scale landslides.
Phi said that another important factor is the building of hydropower dams and water reservoirs on the Mekong mainstream in countries which share the Mekong River’s benefits with Vietnam.
About 120 water reservoirs are expected to be built throughout the Mekong upper course, located in Laos, Cambodia and Thailand. Scientists have estimated that the hydropower plants would lead to a loss of 90 percent of alluvium in 20-30 years, while the current loss ratio is 50 percent.
Nguyen Minh Quang from Can Tho University also commented that MARD’s report was vague and proper solutions cannot be based on the ministry’s report.
He emphasized that the hydropower dams on the Mekong not only have decreased the amount of alluvium to Mekong Delta, but have also affected the flow to Vietnam’s Tien and Hau Rivers.
The landslides have occurred in 406 riverside and coastal areas with total length of 891 kilometers.