不同地形特征下坡面氮磷迁移的物理过程解析与模拟

Water and soil loss is a worldwide environmental problem, which not only causes amount of nutrient loss in soils and thus results in reduction in soil fertility, but also lead to eutrophication on soil surface and results in non-point source pollution. Slope land is the initial unit of water and soil loss, and terrain feature is one of the most important factors influencing water and soil loss. Thus, the concentration on physical process of nitrogen and phosphorus transport on slope land based on terrain feature is one of the fundamental tasks for solving nutrient non-point pollution. In the project, the physical processes of nitrogen and phosphorus transfer over slope land are considered as the main research objects. The approaches of experimental studies, theoretical analysis and model simulations will be adopted to conduct an in-depth and systemic study on the effects of rainfall features and terrain features on nitrogen and phosphorus losses. Features of nitrogen and phosphorus losses on slope land and acting mechanisms will be described, and synchronous transport features of nitrogen and phosphorus on slope land during the processes of infiltration, surface runoff and sediment loss are quantitatively analyzed. Meanwhile, based on the interaction between surface runoff, soil nutrient and water, nutrient transport model will be established. In addition, according to the hydrology module and the sediment yield module in the mature runoff erosion model, physical model describing nitrogen and phosphorus transport processes over slope land during rainfall will also be established. The research results will enrich the theory of matter transport over slope land and provide the scientific theories and methods for predicting the loss amount of water, soil and nutrients on slope land.

水土流失是世界性的环境问题，它不仅使土壤养分大量流失，致使土壤肥力降低，还造成了地表水体的富营养化，引起面源污染。坡面是水土流失的初始单元，地形特征是其最主要影响因素之一，以地形特征为出发点，关注坡面氮磷迁移的物理过程，是寻找解决养分面源污染的最基本工作之一。本项目以坡面氮磷迁移的物理过程为研究对象，以试验研究、理论分析和模型模拟为手段，通过深入系统的研究降雨特征、地形特征等对氮磷流失的影响，揭示坡面氮磷的流失特征及作用机理，并定量分析坡面氮磷在入渗、地表径流及泥沙流失过程中的同步迁移特征，同时根据地表径流、土壤养分与水的相互作用关系，构建养分迁移模块，并借鉴成熟的径流侵蚀模型中水文模块和产沙模块，共同架构描述次降雨条件下坡面氮磷迁移过程的物理模型，为丰富坡面物质迁移理论和预测坡地养分流失提供科学理论与方法。

水土流失引起的农田土壤养分进入水体是水污染事件频发的重要原因。本项目在内蒙古和林格尔野外试验基地和首都圈森林生态系统定位研究站进行了野外定位观测和人工降雨试验，取得了重要的第一手研究数据。研究以坡面氮磷迁移的物理过程为研究对象，以试验研究、理论分析和模型模拟为手段，通过深入系统的研究降雨特征、地形特征等对氮磷流失的影响，揭示坡面氮磷的流失特征及作用机理，并定量分析坡面氮磷在入渗、地表径流及泥沙流失过程中的同步迁移特征，同时根据地表径流、土壤养分与水的相互作用关系，构建养分迁移模块，并借鉴成熟的径流侵蚀模型中水文模块和产沙模块，共同架构描述次降雨条件下坡面氮磷迁移过程的物理模型。项目主要开展了三部分研究内容：a.人工降雨条件下雨强和坡度对黄土坡面氮磷流失过程的影响；b.降雨条件下坡面水土保持措施对水、土、养分流失的影响；c.基于KINEROS2的土壤侵蚀养分流失过程的研究与模拟。其研究内容涵盖了任务书中的所有研究内容，并已发表SCI检索论文学术论文4篇，培养了2名硕士研究生,已经超额完成预期考核指标。本研究将降雨过程、坡面养分迁移过程与地形因素三者的关系动态定量化，并以养分迁移转化理论与成熟的径流-侵蚀模型相结合，建立养分迁移模块，并最终构建了坡面尺度的养分流失的通用模型是十分有意义的，它对于丰富坡面土壤养分迁移理论和建立适合于我国且便于推广应用的非点源污染模型都具有重要借鉴意义。