坡面氮素流失模型的建立与应用

Establishment and Application of Hillslope Nitrogen Loss Model

根据农田土壤氮素流失过程建立了基于次降雨事件的坡面氮素迁移模型,采用G-A方程、运动波方程计算了下渗与坡面流,运用欧洲土壤侵蚀模型模拟了土壤侵蚀,并综合考虑了水—土界面与土壤中的对流扩散过程及氮素迁移过程。以野外实验为例,对该模型进行率定及验证,结果表明该模型结构简单、参数易获取、物理意义明确、模拟地表径流中各形态氮素浓度过程效果较好。

An event-oriented, nitrogen transport model is established to simulate nitrogen transfer processes in farmland slope during rainfall period. The Green-Ampt infiltration equation modified by Chu and the kinematic wave equation are used to estimate the infiltration volume and the overland flow. Soil erosion is computed with the European Soil Erosion Model. Nitrogen transfer from soil to surface runoff is simulated with the model including erosion driven processes and diffusion process. Chemical transport within the soil profile can be described by the onedimensional advection-diffusion equation. This model has the characteristics of simple structure and the meaningful physical parameters. The model calibration and validation are performed with the in-situ measured data, the results show that the model can be used to simulate the nitrogen concentration in surface runoff effectively and the efficiency coefficients during calibration period and validation period were both above 0.85.