Water Quality Assessment and Driving Mechanism Analysis of the Hanjiang River Basin Based on WQI-PCA-OPGD
To reveal the spatiotemporal evolution and driving mechanisms of water quality in the Hanjiang River Basin, this study utilized monthly water quality monitoring data from 54 sections from January 2021 to April 2024. Methods including single-factor index, comprehensive water quality index (WQI), principal component analysis (PCA), and optimal parameters-based geographical detector (OPGD) were employed. Results indicated significant spatiotemporal differences, with total nitrogen (TN), chemical oxygen demand (COD), and permanganate index (CODMn) as major pollutants, TN being the most critical. Temporally, agricultural non-point source organic pollution dominated in wet season, while comprehensive organic pollution with industrial point source characteristics prevailed in dry season. Spatially, water quality deteriorated along the main stream, with tributary downstream areas showing severe pollution, forming a pattern of 'mountainous areas good, plains poor'. OPGD revealed combined effects of natural conditions and human activities, proposing a 'zonal control and targeted treatment' strategy.