Remote Sensing and GIS Application in Surface Water Quality Research in the Chepinska River Basin (Western Rhodopes, Bulgaria)

Unlike traditional water sampling methods for surface water quality analysis and assessment, satellite imagery has good spatial and temporal coverage, allowing analysis of large areas. In this work, we used satellite data from the Copernicus Sentinel˗2 satellite mission, a digital elevation model (DEM), and GIS techniques and methods to extract water bodies in the Chepinska River Basin (Western Rhodopes). The obtained results were analyzed together with the water quality analysis results of in situ measurements and surface water samples, data from the Executive Environmental Agency of the Ministry of Environment and Water, the Ministry of Agriculture, Food, and Forestry, Bulgaria, and high-resolution Global Surface Water Datasets (1984- 2021). The integrated GIS-based analysis allowed us to determine the extent of water bodies in different years and seasons, the degree of surface water pollution, and the points for long-term monitoring of river water quality in the investigated area. The obtained results are also useful for improving the quality of existing data sets available from other sources, such as the East Aegean River Basin Directorate (Plovdiv), and for supporting the Chepinska River basin management.