Effect of Land Use Pattern on Water Quality in Bosten Lake at Different Temporal and Spatial Scales
Limited water resources in arid regions is an important factor constraining development of social production and human life activities.Bosten Lake,the largest inland freshwater lake in the arid region,has contributed greatly to maintaining ecological security and promoting economic development.In this study,the impact of land use patterns on the water quality of Bosten Lake was revealed at different space-time scales by combining redundancy analysis(RDA)with Spearman correlation.Our aim was to provide a reference and data to support effective protection of water quality and ecological management of the Bosten Lake basin.The study was based on Google Earth remote sensing data(2020)and water quality data measured in the normal season(September,2020),wet season(June,2021)and dry season(October,2021)at 23 sampling points of Bosten Lake.Areas within radii of 100,300,500,1 000,3 000 m to the sampling points were set as the buffer zones,which were then overlaid with land use data to obtain the area proportions of different land use types within the different spatial scales.Six land use types were delineated,including cultivated,woodland,grass land,water area,construction land,and bare land.However,woodland and construction land were not included in the analysis because their areas were less than 0.4％of the total area.Results show that:(1)The concentrations of CODMn and TN in Bosten Lake were abnormally high,exceeding Class Ⅲ standards for surface water at 21.7％and 55.1％of the sampling points,respectively,indicating that TN and CODMn were the primary pollutants.(2)There was a significant correlation between land use and water quality within five of the buffer zones.The buffer zones with radii of 1 000,3 000 and 500 m in the wet,normal and dry seasons best explained water quality with explanatory rates of 40.0％,35.6％and 31.1％,respectively.(3)Landscape heterogeneity and fragmentation increased with spatial scale.(4)Among the four land use types,cultivated land was the primary source of water quality deterioration,followed by grassland.Although grasslands can play a posi-tive role in purifying water,inappropriate management has allowed pollutants to enter the water.(5)In terms of the landscape pattern indices,landscape shape index(LSI)correlated positively with NH3-N and TN,and there was a significant positive correlation between the Shannon-Wiener diversity index(SHDI)and NH3-N.This indicates that increased landscape fragmentation leads to deterioration of water quality,but there is a large uncertainty in the correlation between LSI and water quality that will require further in-vestigation.Analyzing how land use affects water quality in Bosten Lake supports the formulation of ratio-nal water quality protection measures and enhances sustainable resource utilization.
temporal and spatial scalesland uselandscape patternwater qualityBosten Lake
万方数据
维普
