流网和一维动力学模型相结合模拟麦田暗管排水地段氮肥的流失

The simplified mathematical model of nitrogen losses in tile effluent from the drained field of winter wheat

为研究麦田暗管排水地段氮肥运移转化及淋失规律， 在地下水位以上的土壤非饱和带建立了氮素运移与转化的一维模型， 在地下水位以下的饱和带采用流网与一维模型相结合近似模拟暗管排水地段的二维溶质运移问题， 这样田间饱和非饱和流动区域即可作为一个整体进行研究， 方法简单、实用． 对方法及模型的正确性进行了田间试验验证．

A simplified Mathematical model of nitrogen transport and transformation is established for field condition. A 1 D model of saturated unsaturated flow is applied when water table is above the drain pipes and a 2 D simplified travel time model is adopted for the flow field below the pipes. The advantage of these methods is that both drainage rate and concentration of nitrogen drained from each stream tube can be calculated and consequently the weighted average concentration of drainage effluent is derived. The field experiments are carried out to demonstrate the validity of the model.