Mapping the water body area by using Sentinel 1 – SAR in dry season of 2023: A case study in Tri An reservoir

Monitoring water surface areas plays an extremely important role, especially for river and reservoir, lake systems that are significant for irrigation, hydropower and ecosystems etc. In the Tri An reservoir area, the main water source for Dong Nai province, and also where many people live in 4 districts of VinhCuu, DinhQuan, Thong Nhat and TrangBom. However, in the dry season of 2023, the weather became hot and dry with little rain due to the influence of the El Nino phenomenon. The water level of Tri An Lake has dropped to a record low in the past 12 years. Based on Sentinel 1 images and threshold method, this study conducted water surface extraction from January May 2023 of Tri An lake. The results showed that, from January to May 2023, the water surface area decreased from 26,270.97 hectares to 10,059.87 hectares. The most obvious decrease in water surface area was in Phu Ly and Ma Da communes (VinhCuu district) and the La Nga bridge section. This study has been a demonstration of the impact of global climate change on water resources, providing a basis for environmental resource management.