地下水污染物迁移演化机理是地下水污染风险评估及防控研究的重要课题。地质体内部存在空间尺度不一、几何分布随机且水文地质参数空间变异的裂隙结构，使得地下水污染物迁移演化过程具有强非线性与高度不确定性。本项目以三峡库区野外大型综合试验场为现场研究基地，在研究地质体裂隙结构与水文地质参数空间分布不确定性特征的基础上，开展考虑地质模型不确定性的地下水污染物迁移演化机理研究。提出一套基于有限地质勘察资料定量表征裂隙地质体不确定性模型的精细建模方法；采用等效孔隙介质-离散裂隙网络（EPM-DFN）耦合模型，提出考虑大范围、大规模密集分布裂隙的地质体地下水污染物多重非线性迁移演化过程的精细模拟方法；探讨裂隙结构与水文地质参数不确定性对地下水污染物迁移过程的影响规律，揭示裂隙地质体模型不确定性条件下地下水污染物迁移演化机理。项目的实施可为我国地下水污染风险评估、防治与修复提供理论参考与技术支撑。

Mechanism of groundwater contaminant transport is an important issue in study of risk assessment, prevention and remediation of groundwater contamination. Discontinuities such as fissure and fracture structures with different spatial scales, random geometric distribution, and varying hydrogeological parameters are present in the geological media, which makes the transport process of groundwater contaminant strongly nonlinear and highly uncertain. This project takes the large-scale comprehensive test field in the Three Gorges Reservoir area as the field research site, and focuses on the evolution mechanism of groundwater pollutants based on the uncertain conceptual site model, which considers the uncertainty characteristics of the spatial distribution of fracture structures and hydrogeological parameters. A precisely modeling approach for quantitative characterization of the uncertainties of fractured geological media with limited geotechnical survey data is proposed. An elegant numerical method based on the equivalent porous medium-discrete fracture network (EPM-DFN) coupled model is developed to precisely simulate the strongly nonlinear migration and evolution of groundwater contaminant in geotechnical site with large-scale and densely distributed fractures. The influences of uncertainties in geological structures and hydrogeological parameters on the migration process of groundwater contaminant are investigated. And the mechanism of groundwater contaminant transport under the uncertainty of conceptual site model will be revealed. This project is expected to provide theoretical and technical support for the risk assessment, prevention and remediation of groundwater contamination in China.