Simulation of nitrogen and phosphorus loss in sloping field

An event-oriented,nitrogen(N)and phosphorus(P)transport model is developed to simulate the N and P transfer processes in farmland slope during the rainfall period. The Green-Ampt infiltration equation modified and the kinematic wave equation are used to estimate the infiltration volume and the overland flow.The soil erosion is computed with the revised Euro-pean soil erosion model. N and P transfer from soil to overland flow is simulated with the model including erosion driven pro-cesses and diffusion process. N and P transport within the soil profile is described by the 1D advection-diffusion equation. The model calibration and validation are performed with the measured data derived from the indoor artificial precipitation experiment,and the results show that the model can be used to simulate the N and P concentration in overland flow effectively,and the efficiency coefficients during calibration period and validation period are both above 0.89. The relationship between rainfall intensity,slope and N,P concentration in overland flow are analyzed.