LMDCZ-AFD PROJECT: STUDY OF EROSION PROCESSES AND PROTECTION MEASURES FOR THE LOWER MEKONG DELTA COASTAL ZONE

The LMD coastal area is influenced by waves, tides, changing sediment loads from the Mekong and Saigon-Dong Nai river system, and storm surges from the East and West Sea. In addition, human activity has an impact on erosion and deposition processes through dyke construction and drainage, agriculture, aquaculture, and fishery exploitation along the coastal areas.

In recent years, the impact of upstream dams, especially on the Mekong main river, has reduced sediment feeding into the LMD and its estuaries. All of these impacts have caused shore erosion along approximately two thirds of the total coastline length, and a land loss rate of about 500 ha/year in the past ten years (Figure below). In the future, the projected sea level rise would make this situation worse. Both experimental and numerical approaches are proposed here.

State-of-the-art numerical models such as ROMS and DELFT3D (3D), TELEMAC-2D and MIKE21 (2D) are used to compute waves, currents, salinity and sediment transports in the LMDCZ. In order to calibrate and validate the models for flows and sediments, observations are needed in Can Tho and Sadec, at the mouth of the Mekong River, and over the shelf area. No such extensive data sets is available yet and we thus planned 2 measurement campaigns, each lasting 15 days, in the Mekong estuaries and in coastal zones (plus stations in Can Tho and Sadec).

The first survey took place in October 2016 and was successful. The second is scheduled for February 2017. This project is funded by the European Union (EU) and the French Development Agency (AFD) and coordinated by institutes from Vietnam (SIWRR) and France (IRD, hosted by the CARE research lab in HCMC) and under the guidance of about 10 international experts from France, Germany and the Netherlands. Institutes VIETNAM: SIWRR, HCMUT (CARE lab), WRU, ... FRANCE: LEGOS, LTHE, ...