Monitoring of Water Surface Dynamics of the Song Hinh Hydropower Reservior (Vietnam) Using Google Earth Engine

Reservoirs are facing increasing hydrological pressure, making continuous and accurate monitoring of these resources essential for sustainable management. In this study, we utilized a method involving Google Earth Engine (GEE), a platform with strong data processing capabilities for big data, to analyze and interpret satellite images. The Otsu method was applied to automatically determine the threshold value for extracting the water surface of the Song Hinh reservoir using Landsat 5, 8, and 9 satellite imagery, and to assess changes in the reservoir’s surface area. The research results indicated that the water surface area of the Song Hinh reservoir initially increased 4.4 times (1999-2000) and then remained relatively stable (2000-2024). However, during the 2000-2015 period, the water surface area experienced minor expansions and contractions, while during the 2015-2024 period, the surface area expanded insignificantly, with less contraction than in the previous period. Additionally, the analysis results of water surface area changes were used to support the development of Earth Engine Apps, also known as WebGIS, as a tool for monitoring surface water changes in the Song Hinh reservoir. In summary, the results obtained in this study are highly useful as a foundation for developing effective monitoring measures and sustainable resource management for the Song Hinh reservoir area.