Remote Sensing-Based Spatiotemporal Assessment of Ecological Quality using RSEI from 2016 to 2025: Gala Lake Basin, Türkiye

Wetland-agricultural basins are among the most sensitive landscapes to ecological change because vegetation dynamics, surface moisture, bare soil exposure, and thermal stress interact within the same hydrological system. This study assessed the spatiotemporal ecological quality of the Gala Lake Basin, Türkiye, from 2016 to 2025 using the Remote Sensing Ecological Index (RSEI). The basin was selected because it contains Gala Lake, associated wetlands, agricultural lands, and seasonally variable water surfaces, making it a representative and environmentally important wetland-agricultural landscape in northwestern Türkiye. Landsat 8 OLI/TIRS and Landsat 9 OLI-2/TIRS-2 images were processed in Google Earth Engine to derive NDVI, WET, NDBSI, and LST, representing greenness, wetness, dryness, and heat, respectively. MNDWI was used to mask open-water areas before RSEI construction. The four indicators were normalized and integrated using PCA, and annual RSEI maps were classified into five ecological quality levels. The results revealed that ecological quality in the basin showed strong interannual variability rather than a uniform trend. The mean RSEI reached its lowest level in 2022 and its highest in 2025. Class-based analysis showed a clear reduction in low-ecological-quality areas and an expansion of moderate-ecological-quality areas by the end of the study period. PCA results confirmed that PC1 captured the dominant ecological gradient in all years, supporting its use for annual RSEI construction. This study demonstrates that RSEI provides a robust and reproducible framework for monitoring ecological quality in wetland-agricultural basins and offers baseline information for long-term environmental management of the Gala Lake Basin.