【摘要】 为探讨流域下垫面污染物排放量、径流条件和本底条件对氨氮（NH₃）、总磷（TP）和高锰酸盐指数(I_Mn)3种面源负荷的影响机制,以涪江流域为对象,构建了分布式水文和面源污染负荷模拟SWAT模型,并采用SWAT-Cup进行了参数率定,在此基础上采用Sobol方法进行了全局性敏感性分析。采用Nash-Sutcliffe系数、相对均方根误差、相对偏差和相对总误差4个指标进行检验,结果表明模拟径流过程和污染负荷与实测值基本相符。各种下垫面条件下,NH₃、TP和I_Mn负荷变化幅度均随着负荷均值的增加而增大,当下垫面为山丘区或自然林草为主的汇流区时,径流条件因子中的坡度和坡长对于面源污染负荷的影响最大。由于农田对径流过程具有显著的调节能力,面源污染负荷随汇流区内农田面积比例增加而降低。土壤本底、面源污染物排放量和径流条件3类因子中,径流条件因子对于面源污染负荷的影响最为敏感,而面源污染物排放量的影响不显著。下垫面对TP负荷的敏感性最弱,对IMn负荷的敏感性最强。因此,加强径流过程调控能力对涪江流域面源污染控制最为有效。更多还原

【Abstract】 The objective of this study is to investigate the impacts of underlying surface conditions,i. e.,discharged sewage from various sources,runoff paths,and soil background TN and TP contents on the ammonia nitrogen（NH₃）,total phosphorus（TP）and permanganate index(I_Mn)loads. The hydrology and transport and transformation processes of the non-point source pollutions at the Fujiang River Basin were simulated with a SWAT model in which the parameters were calibrated by the SWAT-Cup. The global sensitivities of underlying surface condition parameters were evaluated using the Sobol indexes. The Nash-Sutcliffe coefficient,the relative root mean square error,the relative deviation,and the relative total error were used to evaluate the model performance and the results show that the simulated flow rates and NPS loads were accurate. The variation of the NPS pollution loads increased as more pollution discharged into rivers under various underlying surface conditions. The NPS loads were mainly affected by the landscape and the slope length in hills dominated by the natural forests,whereas the NPS loads decreased with the proportion of agricultural land area due to the modulation capacity of the agricultural lands to the runoff. The Sobol sensitivity analysis results demonstrate that flow paths had the most important first-order and total-order effect on the simulated flow and NPS loads. The sensitivity indices of the total phosphorus and the permanganate index were the lowest and the highest,respectively,among three NPS pollutions.Strengthening the control and adjustment ability of the runoff process has the most significant effect on the controlling of non-point source pollution in the Fujiang River Basin.更多还原