苕溪流域非点源污染特征及其影响因子

Characteristics of non-point source pollution in Tiaoxi watershed and related affecting factors

应用土壤水体评价模型(SWAT)对苕溪流域径流量、泥沙、营养盐负荷进行模拟计算,分析了2008年苕溪流域非点源污染的时空分布特性.结果表明:苕溪流域非点源污染单位面积产生量表现为北部高于南部、东部高于西部、中部地区最少;耕地是泥沙和污染物产生的主要来源,其单位面积负荷远大于其他土地利用类型;产流量、产沙量与降水量呈显著正相关关系(P<0.05),雨季(6—9月)的营养盐输出大于旱季(12月至次年3月);平均坡度与泥沙负荷、有机氮负荷及硝态氮负荷呈显著相关关系(P<0.05).

By using soil and water assessment tool（SWAT） model,this paper simulated the surface runoff intensity and the export loadings of sediment particulates and nutrients via non-point source hydrological pathway in Tiaoxi watershed,and integrated with the simulation results,analyzed the temporal and spatial distribution characteristics of non-point source pollution in the watershed in 2008.In the study area,the per unit area non-point source pollution was stronger in northern region than in southern region and in eastern region than in western region,and the weakest in central region.Among the land utilization types,farmland had the biggest contribution to the sediment loading.There were significantly positive correlations between the loadings of surface runoff and associated sediment particulates and the rainfall intensity.The export loadings of nutrients through surface runoff were higher in rainy season（from June to September） than in dry season（from December to next March）,and there existed significant correlations between the surface runoff loadings of sediment particulates,organic nitrogen,and nitrate and the average gradient of lands.