oa Analysis of Reservoir Water Surface Dynamics in the Donetsk Region Based on Remote Sensing Data

In the article, the authors analyzed the dynamics of the water surface area of the Khanzhonkiv, Volyntsivske, and Vuhlehirske reservoirs in the Donetsk region using Sentinel-2 satellite imagery and geospatial analysis in Google Earth Engine (GEE). The dataset includes 28 Sentinel-2 images for Khanzhonkiv, 45 for Volyntsivske, and 31 for Vuhlehirske Reservoir, covering the period 2019–2025. The Normalized Difference Water Index (NDWI) was calculated to generate water surface masks with a spatial resolution of 10 m. For each date within the study period, the water surface area of the reservoirs (in hectares) was determined and visualized graphically. The results indicate an approximately 80% reduction in the water surface area of the Khanzhonkiv Reservoir during the summer of 2025 compared to 2022, with water levels in spring 2025 decreasing by 2.22 m compared to spring 2023. Complete desiccation of the Volyntsivske Reservoir was observed in spring 2024, with a water level decrease of 6.38 m. The loss of the water surface area of the Vuhlehirske Reservoir is 16%, taking into account seasonal fluctuations in the water level above inland waters. The degradation of these reservoirs, driven by anthropogenic impacts, poses environmental, humanitarian, and strategic challenges. Statistical assessment and cartographic materials reveal intra-annual variability, providing insights into reservoir behavior under climatic and anthropogenic influence. The approach proposed by the authors demonstrates the practical integration of online cloud-computing platforms and spectral index analysis into geoinformatics research focused on monitoring inland waters, particularly reservoirs in Ukraine.