Response Relationship of Land Use in Karst Landscapes to River Water Quality in a Multifactorial Perspective:a Case Study of Chishui River Basin
The objective of this paper is to probe into the relationship between land use and river water quality in karst landscapes in terms of varied spatial scales,seasons,and topographic slopes.On the basis of the river-water monitoring data of TN and TP concentrations of of the Chishui River(Yunnan Section)in 2021 within the typical karst geomorphologic basin of northeast Yunnan Province in combination with remote sensing images of the types of land-use and slope,quantitative description about the response of water quality to land-use in the watershed was made according to four spatial scales:200 m buffer zone,500 m buffer,1 000 m buffer zone,as well as the sub-watershed.Results showed the water quality of the river-water of Chishui River Basin(Yunnan Section)in 2021 ranged between categories Ⅰ and Ⅲ,accounting for 87.0％of the total;so generally the quality of the water environment was good,except for TN concentration,which exceeded the the relevant state standard by more than four times in some sections.Owing to the enhancement of spatial scale and the posi-tive correlation between forest-land and TN,the correlation in the lower sub-watersheds scale was significant(0.720,P＜0.05),and the multiple linear regression R-square fitting results showed that the sub-basin scale has the highest degree of explanation for water quality changes;steep-slope forest land was positively correlated with TP during the wet season(0.795,P＜0.05),with TN during the level period(0.728,P＜0.05),and with the dry season(0.800,P＜0.01);while the gen-tle-slope land for construction was significantly in positive correlation with TN during the wet season(0.733,P＜0.05);these significant correlations were mainly located in the areas with gentle-slope and steep-slope;and forest land,pasture-land,and farmland were the main factors affecting the change of water quality;however among others,pastureland though accounting for the smallest proportion of the watershed area,it had a considerable impact on the river water quality.There-fore,the adequate management of pastureland could improve the river water quality with higher efficiency.It is expected that the research achievements could provide a theoretical basis for studying the impacts of land use on river water quality in the area of karst landscape.
nitrogen and phosphorus pollutionterrain slopeland usekarst landscape
万方数据
维普
