Satellite data and applying the DSAS tool to shoreline change assessment of the Mekong Delta

The Mekong Delta is the third-largest delta in the world, with a large population, a significant food production area in Vietnam and home to large-scale biodiversity, is seriously affected by erosion - accretion of the coast, land subsidence. Several dams have been built upstream of the delta (Manwan, Nuozhadu…), and large-scale commercial sand mining in the river and delta channels, along with subsidence caused by groundwater extraction, are the causes of sediment decline in the Mekong Delta. This affects the daily lives of more than 21 million people. Using high-resolution satellite imagery (Landsat) for the period 1989-2020, this paper assesses erosion-accretion rates at the Mekong estuary to Ca Mau cape. Extracting the shoreline using the Normalized Difference Vegetation Index used to measure vegetation change and the Digital Shoreline Analysis System used to analyze changes in the shoreline. The results show that the Mekong estuary is having an alternating process of erosion-accretion, the balance of erosion-accretion tends to imbalance with dominant accretion. The Mekong estuary area, including the Tieu, Dai, Ba Lai, Ham Luong, Co Chien, Cung Hau, Dinh An and Tran De mouths, experiences erosion and accretion ranging from 1.37 to 120.98 m/yr and 74.94 to 117.06 m/yr, respectively. From My Thanh mouth to Ca Mau Cape, with erosion ranging from 66.07 to 115.5 m/yr and accretion from 29.67 to 91.06 m/yr, respectively. Our research emphasizes the fragility of the Mekong Delta coastline and underscores the critical role of remote sensing imagery in effective shoreline management.