铁山水库流域非点源污染负荷研究

Non-point source pollution load in Tieshan Reservoir Basin

【目的】研究铁山水库流域非点源污染负荷的空间分布规律及影响因素,为铁山水库流域水质保护与非点源污染控制提供参考。【方法】建立了铁山水库流域的水土评价模型(soil and water assessment tool,SWAT),并运用该模型研究了流域总氮和总磷非点源污染排放强度与贡献率的空间分布特征及3种不同土地利用情景下非点源污染的变化情况。【结果】SWAT模型在模拟铁山水库流域水流和污染物运移过程方面精度良好。铁山水库流域非点源氮素主要来源于库区农田耕作过程中施加的化肥,而流域非点源磷素则主要来源于库区分散农村人口排放的生活污水及库区农田耕作过程中施加的化肥。流域非点源总氮和总磷污染负荷量在1995—2015年间分别下降了49.26%和86.66%。【结论】在流域内进行退耕还林及人口集中与外迁安置对流域非点源污染控制具有积极作用。

[Purposes]This study investigated the spatial distribution characteristics and impact factors of nonpoint source pollution of Tieshan Reservoir Basin,so as to provide reference for water quality protection and non-point source pollution control for this basin.[Methods]A soil and water assessment tool(SWAT)model of the Tieshan Reservoir Basin was established to analyze the spatial distribution characteristics of the emission intensity and contribution ratio of non-point source pollution of total nitrogen(TN)and total phosphorus(TP).Besides,the non-point source pollution under three different land use scenarios was also studied.[Findings]The established SWAT is of good precision in simulating the water flow and pollutant transport processes in Tieshan Reservoir Basin.The non-point source pollution of TN is mainly from the applied fertilizers,while the non-point source pollution of TP is mainly from the rural domestic sewage and the applied fertilizers.The nonpoint source pollution of TN and TP in Tieshan Reservoir Basin decreased by 49.26%and 86.66%,respectively,from 1995 to 2015.[Conclusions]For the Tieshan Reservoir Basin,the“grain for green”program and the population centralized resettlement and relocation have positive impacts in decreasing non-point source pollution of TN and TP.