地表覆盖层结构对地面径流和土壤侵蚀过程的影响机制

Straw and gravel mulch are important dry farming measures, have attracted extensive attention from scholars at home and abroad because of their good water retention effect. Straw and gravel mulch can significantly change soil environment and hydrological processes, but the mechanism of the mulch layer structural changes affecting the surface runoff, soil erosion and nutrient elements loss processes is not clear, and the analog computation of soil hydrological process under mulch layer is still unavailable now due to the lack of comprehensive and sensitive mulch layer structural characteristic parameters and complex hydrological process changes after mulching. This project aims to make the mechanism of the mulching layer structural changes affecting the surface runoff, soil erosion and nutrient elements loss process clear and definite through the observations of the effects of straw and gravel mulch layer structure changes on soil hydrological process, and establish models for surface runoff, soil erosion and nutrient element loss processes under surface mulching, which are adapt to different mulching layer types and structures. So as to provide theoretical support for optimizing the surface mulching layer structure and improving the water productivity and fertilizer utilization ratio of dry farmland, and also provide parameters and basis for simulation study of land surface hydrological processes under surface mulching.

秸秆和砾石覆盖是重要的旱作农业措施，因其良好的保水效应在国内外受到广泛关注。秸秆和砾石覆盖能够显著的改变土壤环境和水文过程，但其覆盖层结构变化影响地表径流、土壤侵蚀和营养元素流失等过程的机制还不清楚，并且由于缺乏敏感的综合性覆盖层结构特征参数和覆盖后水文过程的复杂变化导致目前覆盖下土壤水文过程无法模拟计算。本项目拟通过观测秸秆和砾石覆盖层结构变化对土壤水文过程的影响，明确覆盖层结构特征影响地表径流、土壤侵蚀和营养元素流失过程的机制，建立适应不同覆盖层类型和结构的，能够准确模拟地表径流、土壤侵蚀和营养元素流失过程的模型。为优化地表覆盖层结构、提高旱作农田的水分生产率和肥料利用率提供理论支持，也为地表覆盖下陆面水文过程的模拟研究提供参数和依据。

本项目通过自然降雨条件下的径流场观测和人工模拟降雨观测相结合，分析了特征参数化的不同地表覆盖层结构下黄土高原土壤的地表径流和土壤侵蚀过程，揭示了地表覆盖层结构对降雨截留、水分入渗、地表径流、土壤侵蚀和营养元素流失等主要水文过程的影响，研究了砾石覆盖和自然降雨共同作用对土壤质量和土壤微生物群落的影响。明确了地表覆盖层结构参数与主要水文过程参数之间的定量关系，并初步建立了砾石覆盖层下的地表径流和土壤侵蚀模型。