Spatiotemporal Variation and Sources of Water Quality in a Typical Small Watershed in Southern China
DUAN Huxia
YU Dezhong
ZHANG Qiuying
Abstract：Small watersheds in southern China exhibit significant spatiotemporal variations in water quality due to human activities,with complex influencing factors and difficult-to-identify pollution sources,making them a current hotspot in watershed environmental research.There is an urgent need for monitoring studies at dense spatiotemporal scales to identify all possible pollution sources and clarify their contributions to water quality.Taking the Baisha River,a small watershed in western Guangdong Province,as an example,monthly sampling was conducted from August 2022 to January 2023.Spatial analysis,correlation analysis,principal component analysis(PCA),and absolute principal component scores-multiple linear regression analysis(APCS-MLR)were used to analyze the spatiotemporal distribution patterns and source contributions of water pollution.The results show that spatially,upstream water quality is better than downstream,and mainstream water quality is better than tributaries.Temporally,water quality is worse during the dry season.In terms of water sample types,fishpond total nitrogen(TN)and total phosphorus(TP)levels exceed those of tributaries and mainstreams by 37%and 160%,respectively.In planting areas,NH4+-N,TN,and TP average concentrations are 688%,268%,and 510%higher than in non-agricultural and non-aquaculture areas,while in aquaculture areas,they are 1 273%,801%,and 1 071%higher,suggesting that fishponds,aquaculture,and planting may be the main pollution sources affecting watershed water quality.PCA revealed that the first and second principal components explained 36.7%and 20.5%of the total variance,respectively.Further APCS-MLR analysis showed that the first principal component contributed 69.92%,76.24%,and 68.8%to NH4+-N,TN,and TP,respectively,mainly originating from agricultural planting and aquaculture non-point source pollution.Combining field surveys with experimental analysis,this study explored the factors influencing water quality and identified pollution sources in the BaiSha River Basin,revealing that agricultural non-point sources are the primary contributors of nitrogen and phosphorus pollution.The findings provide guidance for the scientific prevention and control of water pollution in small watersheds in western Guangdong Province.
Keywords：small watershedspatiotemporal variationwater qualityagricultural non-point sourceaquacultureBaisha Riversource analysis
Publication Date：2025-10-20
Online Publishing Date：2025-11-12(First online date of this platform, not the publication date of the document)
Pages：8( 12-19 )