土壤结构分形与水动力特征关系研究

The thickness of vadose zone is continuous increasing which has induced the textural anomaly of shallow aquifers in the North China Plain. The traditional moisture dynamic monitoring methods are unsustainable. From the angle of the medium itself attribute soil structure characteristics, the program want to study the the evolution of the hydrodynamic characteristics. This study is located in the Taihang Piedmont Plain. Using the fractal theory and the principles of statistics is to study typical soil texture and structure characteristics in the form of fractal comprehensive classification. And soil structure classification model will be constructed with fractal characteristic value and characteristic interval for the fabric. And under the condition of constant temperature, all kinds of soil moisture characteristic curve will be measured, thereby to determine the hydrodynamic characteristics of the soil structure classification mode. On this basis, we can explore the the relation between the soil structure and spatial variability of hydrodynamic characteristics, and the relation between the soil structure and moisture absorption lag effect, and ultimately determine the soil water dynamic characteristics in the study area. This can provide the reference and scientific basis for studying the moisture migration in deep vadose zone, the nonlinear relationship for recharge between the vadose zone and saturated zone and the whole groundwater flow field.

包气带持续增厚诱发华北平原浅层含水层结构异常，传统的水分动态监测研究方法难以为继，本研究从介质本身属性--土壤结构特征的角度入手，研究水动力特征演变方式。立足于太行山前平原，利用分形理论，借助统计学原理，将典型区土壤质地和结构特征以分形形式综合分类表达，构建了以分形特征值和特征区间为经纬的土壤结构分类模式。并在恒温条件下测定各类别土壤的吸、脱湿水分特征曲线，从而确定土壤结构分类模式下的水动力特征。在此基础上，探寻土壤结构与水动力特征空间变异的相关关系，与吸、脱湿滞后效应的相关关系，并最终确定研究区土壤水动力特征。为解释包气带水分运移形成规律、非饱和-饱和带的非线性补给关系，乃至整个地下水流场研究，提供参考和科学依据。

传统的包气带水分动态监测计算方法不能有效应对持续增厚的浅层含水层中复杂科学问题，本项目从介质本身属性特征——土壤粒径分布（PSD）的分形维变异特征角度入手，研究了水分时空分布规律的发生机理，使土壤基本性与流场性质发生科学关联。根据华北和甘肃典型盆地的山前、中部和东部滨海的不同深度土壤分形维计算研究表明：分形维较高，土壤中的粘粒含量较多，土壤的非均匀性增加，此时，土壤容积密度增大，而饱和导水率减小。因此，土壤粒径分布分形可以作为反映土壤物理性质的指标。特征值越大，特征区间下的分形均值差异越小，水力性质差异越小。在较小区间分形特征值变化较大，饱和渗透系数变化同样较大。本成果为解释华北平原深厚包气带水分运移规律、非饱和带-饱和带的非线性补给关系，提供了新思路和有效技术支持。