Monitoring changes in reservoir area and volume is crucial for effective water resource management. The aim to provide a scientific and data-driven approach to monitor, manage, and protect reservoir areas and their ecosystems, leading to better environmental conservation and sustainable development practices. We then compared the area and volume estimates over time to assess changes in the reservoir. In this study, we proposed Sentinel-2 imagery and Sentinel Application Platform (SNAP) software to monitor changes in reservoir area and volume over time. We acquired multiple sets of Sentinel-2 imagery over a period of two years and processed them using SNAP to obtain classified images of the reservoir area. Our results showed a decreasing trend in reservoir area and volume over a two-year period. The study highlights the importance of using Sentinel-2 imagery and Sentinel Application Platform (SNAP) software for monitoring changes in reservoirs and provides insights into the management of water resources in the region.