江苏固城湖流域1951-2000年农业非点源氮、磷输移的数值模拟研究

选择位于长江下游的固城湖流域作为研究区域,基于分布式流域水文模型SWAT,采用数值模拟的手段,反演了1951～2000年流域农业非点源氮、磷的输移规律。模拟结果与实测值的一致性反映了模型的良好模拟能力。比较两个时段的模拟结果发现,1981～2000年,流域农业非点源氮、磷年平均浓度和输移量分别为:总氮0.82mg/L和411.88×103kg/a,总磷0.084mg/L和43.04×103kg/a;远高于1951～1960年的氮、磷年平均浓度和输移量分别为:总氮0.22mg/L和49.55×103kg/a,总磷0.036mg/L和7.67×103kg/a。模拟主要反映了流域下垫面条件和农作物耕作模式对农业非点源氮、磷浓度及输移量的影响。

NUMERICAL SIMULATION ON TRANSPORTATION CHANGES OF AGRICULTURAL NON-POINT SOURCE OF NITROGEN AND PHOSPHORUS IN GUCHENG LAKE BASIN,JIANGSU PROVINCE,DURING 1951-2000

A distributed watershed hydrologic model SWAT(Soil and Water Assessment Tool)was used to simulate transportation changes of agricultural non-point source of Nitrogen and Phosphorus during 1951-2000 in the Gucheng Lake Basin,which is located in the lower reach of Changjiang River.The simulated result was validated by the observed value,suggesting the validity of SWAT model.The simulated total nitrogen(TN)and total phosphorus(TP)in the outlet of the discharge between two periods,i.e.1981-2000 and 1951-1960,were compared.The result indicates that,after land reclamation in the mid-1970s,the average annual concentration and output of TN and TP in 1981-2000 were 0.82mg/L,411.88×10³kg/a and 0.084mg/L,43.04×10³kg/a respectively,much higher than those in 1951-1960,which were 0.22mg/L,49.55×10³kg/a and 0.036mg/L,7.67×10³kg/a.The simulation provides better understanding on transportation changes of agricultural non-point source of Nitrogen and Phosphorus responding to variations of land boundary conditions and the agricultural cultivation,etc.