Solving six challenges of the Mekong Delta

According to Deputy Minister of Agriculture and Rural Development Nguyen Hoang Hiep, in nearly a year, the Prime Minister has twice issued a document assigning the Ministry of Agriculture and Rural Development (MARD) to have a comprehensive solution for the situation of subsidence, landslides, flooding, drought, saltwater intrusion, and domestic water in the Mekong Delta.

Implementing the Prime Minister's direction through the two documents mentioned above, MARD assigned the Southern Institute of Water Resources Research to urgently develop a "Project to prevent subsidence, landslides, flooding, drought, and saltwater intrusion in the Mekong Delta" (referred to as the Project).

At the report session on the draft Project, Dr. Tran Ba Hoang, Director of the Southern Institute of Water Resources Research, said that the Mekong Delta currently has 94% of the area with an elevation of less than 2 m that is very sensitive to flooding, flood tides, and saltwater intrusion. The Mekong Delta has soft geology, so it is easy to erode.

In recent times, there have been three factors that are having a strong impact on the Mekong Delta: development upstream of the Mekong River; climate change - rising sea levels; and subsidence and lowering of the river bed. Of which, development upstream of the Mekong River is contributing to increased saltwater intrusion, increased coastal erosion, and a lack of fresh water. Climate change causes flooding and increases saltwater intrusion. Subsidence and lowering of the river bed also increase saltwater intrusion, flooding, and difficulty in terms of water drainage.

Due to the impact of development upstream of the Mekong River, flood season flow in the Mekong Delta is fluctuating in a downward trend compared to before. Specifically, from 2011 and earlier, every 4–5 years there would be a medium or large flood. But since 2012, small floods have continuously appeared, and no flood peak has exceeded alert level 3. In the distant future, about 30–50 years from now, the number of years with large floods will be almost negligible, and years with small floods, even without floods, will increase sharply.

Since 2013, saltwater intrusion has appeared 1–1.5 months earlier than in the 2004–2012 period. The peak of the saltwater intrusion season has also shifted 1–1.5 months earlier than in the 2004–2012 period. In the dry season of 2023–2024, saltwater intrusion appeared at the end of December 2023, 1 month earlier than the average for many years.

Saltwater intrusion is continuing to increase. It is forecast that by 2030, the salinity boundary of 4 g/l will increase by an average of 3.34 km compared to the present; by 2050, it will increase by an average of 6.7 km compared to the present.

The situation of subsidence in the Mekong Delta is also happening continuously. Surveys by the Ministry of Natural Resources and Environment show that the Mekong Delta is being subsided by an average of 0.5–3 cm/year; coastal areas alone experience subsidence at an average of 1.5–2.5 cm/year. Assuming the rate of subsidence is not controlled (still maintained at the current level), the Mekong Delta commonly subsides from 0.5 to 3 cm/year, except the Ca Mau peninsula sinks at 1.5–3 cm/year. It is forecast that by 2100, many areas in the Mekong Delta will be lowered by 1.5–2.0 m.

Meanwhile, riverbank and coastal landslides in the Mekong Delta are appearing more and more often. In particular, landslides have occurred due to drought.

Speaking at the project reporting session, many experts and managers said that the Project must approach issues in the direction of natural disaster risk management in the Mekong Delta and pay attention to non-structural solutions such as reorganizing agricultural production, improving forecasting and warning capacity, etc.

Deputy Minister of Agriculture and Rural Development Nguyen Hoang Hiep emphasized: The "Project to prevent subsidence, landslides, flooding, drought, and saltwater intrusion in the Mekong Delta" must comprehensively address landslides, subsidence, flooding, drought, saltwater intrusion, and domestic water. With these issues, it is compulsory to base them on practical conditions to solve them step by step, but there are things that must be resolved thoroughly, such as Western coastal landslides, a lack of domestic water, etc. In addition to structural solutions, non-structural measures must also be included in the project, especially converting agricultural production according to planning and water sources. Besides, it is necessary to emphasize improving forecasting and warning capacity in fields under the management of the agricultural sector and provide solutions in science and technology.