农田干缩裂隙与土壤优先流

Existing results showed that the dry shrinkage crack on farmland soil has an important position in soil preferential flow, solute transport and environmental pollutant migration. This project will use the topological method to study the quantitative evaluation index of dry shrinkage crack on farmland soil, revealing its morphology and spatial variation, and to establish the stochastic network model based on Hooke's law through the direct and indirect experimental method ; Considering the soil fissure as a condition of soil preferential flow way of startup, to study the production and influence of soil preferential flow under the fracture network structure; Revealing the soil cracks and soil matrix interaction mechanism, the soil moisture model in fractured network stochastic and non-steady state soil water flow model coupling, based on the soil fissure network and the coupling model of continuous media. The results can improve the understanding on unsaturated soil water movement and solute transport; it has the important application value to improve the efficiency of agricultural water use for guiding the agricultural irrigation.

已有结果表明农田土壤干缩裂隙在土壤优先流、溶质运移和环境污染物的迁移方面具有重要地位。本项目通过直接与间接的实验方法,采用拓扑学方法，研究农田土壤干缩裂隙的量化评价指标，揭示其形态结构及空间变化规律，并建立基于胡克定律的网络随机模型；考虑土壤裂隙作为土壤优先流通道的启动条件，研究土壤裂隙网络对土壤优先流的产生和影响；揭示土壤裂隙与土壤基质相互作用机理，将土壤裂隙随机网络水分模型与非稳态土壤水流模型耦合，建立基于土壤裂隙网络与连续介质的耦合模型。研究结果将提高对非饱和土壤水分运动以及溶质运移规律的认识，对于指导农业灌溉，提高农业用水效率有着重要的应用价值。

已有结果表明农田土壤干缩裂隙在土壤优先流、溶质运移和环境污染物的迁移方面具有重要地位。本项目通过直接与间接的实验方法,（1）研究了农田土壤表面干缩裂隙发展规律以及形成机理，改进裂隙开裂模型并模拟了二维裂隙开裂的动态过程；（2）通过土壤裂隙网络对坡面流及土壤水分入渗运动的影响研究，构建土壤裂隙网络、土壤基质与地表水流运动耦合模型，研究裂隙网络存在下的地表径流运动及土壤水流运动；（3）使用多重分形理论对比分析了作物根系对农田土壤裂隙的影响，同时证明了多重分形理论可以作为指标对模型模拟裂隙与农田土壤裂隙进行评价。研究结果将提高对农田水分运动以及溶质运移规律的认识，对于指导农业灌溉，提高农业用水效率有着重要的应用价值。