Abstract

The Tarthar Lake is an artificial lake that is among the largest in Iraq and that is very vital in controlling floods, water storage and water sustainability in the region dependent on arid climatic conditions. This paper evaluates spatiotemporal changes in surface water area and water sustainability on the basis of the Normalized Difference Water Index (NDWI) of three Sentinel-2 multispectral images taken during the years 2015, 2020 and 2025 on Tharthar Lake. The satellite data was preprocessed using a Geographic information systems GIS-based structure and NDWI was calculated using this structure and changes in water distribution and relative water volume were analyzed with reference to time. The findings indicate that there is a distinct temporal change in the NDWI values that show that there is a change in the lake water surface and internal hydrological processes. The comparison of the years 2015 and 2020 shows that NDWI is high, which is the characteristic of a comparatively stable and large body of water, and the year 2020 demonstrates that there were partial recessions of the shoreline and redistribution of water space. The NDWI map of 2025 indicates that the high-value zones of NDWI are noticeably reduced, which implies that the volume of water decreases and the hydrological pressure increases. These transformations are explained by the fluctuation in inflow, evaporation, and water management styles. All in all, the research illustrates the efficiency of Sentinel-2 image and GIS to track the lake water dynamics and offer meaningful information about the long-term sustainability of Tharthar Lake in the context of the changing environmental and climatic conditions.