Abstract

The erosion and accretion processes have been strongly happening throughout the coast and estuaries of our country, causing significant socio-economic losses. This phenomenon is the result of the interaction of complex processes of hydrodynamic hydrolithic factors due to endogenous, exogenous and anthropogenic effects. Soc Trang province, a coastal province, currently has a rather complicated situation of landslides and accretion, strongly affecting people's livelihood in the region. The article focuses on the establishment of the coastal risk map of Soc Trang province based on the formula of Sunamura and Horikawa according to the 29/2016/TT-BTNMT Circular dated October 12, 2016 on Technical Regulations on establishing coastal protection. This formula is a function with terms of seafloor slope, offshore significant wave height, and wave crest period. In which, the mean offshore wave height and wave crest period will be calculated by the Mike 21 SW model. The results show that the trend of shoreline evolution in the area is accretion. Under the influence of waves and topography of the area, the rate of accretion in the northeast monsoon is higher than that in the southwest monsoon season. In both seasons, the coastal area near the Soc Trang - Bac Lieu border has the highest risk of accretion (ER_max = 0.46 - Northeast monsoon season and ER_max = 0.25 - Southwest monsoon season). In the Hau estuary, the risk of accretion in the northeast monsoon season is in the range of 0.27 - 0.36 while it is lower (0.11 - 0.18) in the southwest monsoon.