Analysis of the temporal and spatial distribution of water quality in China's major river basins, and trends between 2005 and 2010

In this study, based on environmental quality monitoring data on 22 pollutants from 490 control sections, we analyzed the spatial distribution and temporal changes of water quality in ten Chinese river basins (watersheds) to reveal the trends from 2005 to 2010. We used a comprehensive water pollution index (WPI) and the proportions of this index accounted for by the three major pollutants to analyze how economic development has influenced water quality. Higher values of the index represent more serious pollution. We found that WPI was much higher for the Hai River Basin (1.83 to 5.60 times the averages in other regions). In the Yangtze River Basin, WPI increased from upstream to downstream. The indices of some provinces toward the middle of a basin, such as Hebei Province in the Hai River Basin, Shanxi Province in the Yellow River Basin, and Anhui Province in the Huai River Basin, were higher than those of upstream and downstream provinces. In the Songhua, Liao, and Southeast river basins, WPI decreased during the study period: in 2010, it decreased by 33.9%, 44.3%, and 67.2%, respectively, compared with the 2005 value. In the Pearl River, Southwest, and Inland river basins, WPI increased by 23.1%, 47.7%, and 38.5% in 2010, compared with 2005. A comparison of WPI with the GDP of each province showed that the water pollution generated by economic development was lightest in northwestern, southwestern, and northeastern China, and highest in central and eastern China, and that the water environment in some coastal regions were improving. However, some provinces (e.g., Shanxi Province) were seriously polluted.