农田干缩裂隙网络与土壤裂隙优先流观测体系构建及精准模拟

Due to the complex spatial structure of the farmland shrinkage fracture network and the nonlinearity of the flow of soil fracture preferential flow, traditional methods of observation and the model of prediction, whether the physical basis or non-uniform movement of the process are facing many problems. Therefore, this subject takes the dry shrinkage fracture network of farmland and the preferential flow caused by dry shrinkage crack as the research object, using the high density resistivity method as the measurement means, precise characterization system basing on the successive liner estimation inversion algorithm will be developed to characterize soil desiccation crack networks and preferential flow caused by dry shrinkage crack.The characteristics, structure description, spatial variation rule of characteristic parameters and the mechanism of soil preferential flow process and scale change characteristics of dry shrinkage fracture network in farmland were studied.Finally, the soil dry shrinkage cracking model and the coupling model of soil fracture network and matrix flow are improved to improve the prediction accuracy and achieve accurate simulation. The research results have important scientific value for the theory of non-uniform water movement in soil.

由于农田干缩裂隙网络复杂的空间结构和土壤裂隙优先流流动的非线性，传统的观测方法与预测模型无论是物理基础还是预测非均匀运动过程都面临诸多问题。因此本课题将农田干缩裂隙网络及因干缩裂隙引起的优先流作为研究对象，发展以高密度电阻率法为测量手段，基于连续线性估计反演算法的农田干缩裂隙网络与土壤裂隙优先流全局性、连续性观测体系，研究农田土壤干缩裂隙网络发育过程特征、结构描述及特征参数空间变化规律和干缩裂隙存在下，土壤优先流运动过程机理及尺度变化特征，最终改进土壤干缩开裂模型及土壤裂隙网络与基质水流耦合模型，提高模型预测精度，达到精准模拟。研究成果对于完备土壤水分非均匀运动理论具有十分重要的科学价值。

已有研究结果表明农田土壤干缩裂隙与土壤裂隙优先流的耦合的精准模拟在土壤优先流、溶质运移和环境污染物的迁移方面具有重要地位。本项目将试验和数值模拟相结合，（1）通过监测裂隙存在下土壤中的直流电场，构建基于连续线性估计反演算法的农田干缩裂隙网络动态过程观测体系，研究了裂隙网络发育过程与结构特征及不同空间尺度下网络结构拓扑学参数的变化响应；（2）通过监测土壤裂隙存在下土壤水分变化的电场，构建基于连续线性估计反演算法的土壤电阻率空间观测体系，分析土壤裂隙优先流运动过程与规律，揭示农田裂隙网络形态对土壤裂隙优先流的影响机理；（3）基于上述研究成果对土壤干缩开裂网络模型进行优化，并改进土壤裂隙网络与连续介质水分运动耦合模型，提高模型预测精度。