Identifying the water quality variation characteristics and their main driving factors from 2008 to 2020 in the Yellow River Basin, China

Understanding of the water quality dynamics and their main influence factors is crucial for sustainable water environment management especially in the sensitive ecosystem area. Here, the spatiotemporal dynamic of water quality in the Yellow River Basin from 2008 to 2020 and its relationship with physical geography, human activities, and meteorology were studied by using Pearson correlation test, and a generalized linear model. The results showed that water quality was significantly improved since 2008, which was reflected from the decreasing trend of the permanganate index (CODMn) and ammonia nitrogen (NH3-N), and increasing trend of the dissolved oxygen (DO). However, the total nitrogen (TN) remained severely polluted with average annual concentration inferior to level V. Spatially speaking, the water quality in the upper and lower reaches was better than that of the middle reaches. The whole basin was severely contaminated by TN with 2.62 +/- 1.52, 3.91 +/- 1.71, and 2.91 +/- 1.20 mg L-1 from upper, middle, and lower reaches, respectively. Thus, TN should be paid much attention in the water quality management of the Yellow River Basin. The water quality improvement could be attributed to the reduction of pollution discharges and ecological restoration. Further analysis found the variation of water consumption and increase of forest and wetland area contributed 39.90% and 47.49% for CODMn and 58.92% and 30.87% for NH3-N, respectively. Meteorological variables and total water resources contributed slightly. This study is expected to provide in-depth insights for the water quality dynamics and their response to human activities and natural factors in the Yellow River Basin, which could provide theoretical references for water quality protection and management.