Using Multispectral Satellite Images to Estimate Alteration in the Water Surface Area of Lake Dankia During the 2020--2021 Dry Season, Lam Dong Province, Vietnam

Abstract

Vietnam in recent years, especially in the Central Highlands and the South Central region, is experiencing severe droughts due to global climate change, depletion of the surface water resources and intensive agricultural production. The study used four Sentinel 2 MSI satellite images received during the 2020--2021 dry seasons to evaluate alteration in the water surface area of Lake Dankia in the Lam Dong Province of the Vietnam Central Highlands. Optical green channel (channel 3) and shortwave infrared channel (channel 11) of the Sentinel 2 images were used to calculate the modified normalized difference water index MNDWI and to decipher the land--water boundary by the thresholding method. The obtained results demonstrated that the Lake Dankia area at the dry season end (March 18. 2021) decreased by 86.46 hectares compared to November 18. 2020 (dry season start), which was 31.7 % of the original lake area. This study shows that the Sentinel 2 MSI satellite images could be effectively used to monitor alterations in the surface water area and provide valuable input information for models to assess the drought impact on water resources in the areas