华北平原典型区咸水下移机理及数值模拟研究

Downward intrusion of shallow saline groundwater in the North China Plain (NCP) has caused a large number of extraction wells in deep aquifer disabled due to salinization of deep groundwater in the past decades, then control and prevention of downward intrusion of saline groundwater is of great significance to sustainable use of groundwater resources in the NCP. Meanwhile, understanding of the mechanism of downward intrusion of saline groundwater is a fundamental prerequisite for effective control of its continuing downward movement. On the basis of previous work, this project, taking Hengshui City as a typical area of the central part of NCP, seeks to investigate the mechanism of downward intrusion of saline groundwater by a variety of techniques such as chemico-osmosis experiment and tracer test. Furthermore, this project establishes the numerical modeling of groundwater in the area of interest to reproduce the dynamic evolution of downward movement of saline groundwater under variable density conditions, and uses the calibrated simulation model to examine the impact of human activities and evaluate the degree of importance of the main controlling factors. Finally, the numerical simulation model is coupled with the optimization model to seek for sustainable groundwater use patterns in the modeled area. This project is expected to achieve a breakthrough in theory of mass and solute transport in groundwater through low-permeability sedimentary layers. The research results of this project will also offer the scientific basis for decision making of regional groundwater resources for sustainable use. This project has a positive impact on environmental protection and development and utilization of groundwater resources in the NCP of China.

华北平原浅层咸水下移已造成大量深层水的开采井因水质变咸而停用，因此控制咸水下移对华北平原地下水资源可持续利用意义重大。而揭示咸水下移机理是有效控制其持续下移的根本前提。本项目以华北中部平原的衡水市作为典型研究区域，在总结和吸收前人研究成果的基础上，借鉴国内外先进经验和方法，利用包括化学渗透试验在内的多种方法深入研究咸水下移的内在机理。在此基础上，进一步通过建立变密度条件下咸水下移的数值模型，来再现人类活动影响下咸水下移的动力演变过程，并由此讨论影响咸水下移的主控因素及其相对重要程度。最后，将数值模拟模型与优化模型相耦合,寻求该区地下水资源的可持续利用模式。本项目研究有望在弱透水粘性土层中地下水的溶质运移理论上有所突破。同时，本项目的研究成果可为研究区域地下水资源可持续利用提供科学决策依据，将对我国地下水资源的开发利用与环境保护带来积极的影响。

华北平原浅层咸水下移已造成大量深层水的开采井因水质变咸而停用，因此控制咸水下移对华北平原地下水资源可持续利用意义重大。而揭示咸水下移机理是有效控制其持续下移的根本前提。本项目以华北中部平原的衡水市作为典型研究区域，在总结和吸收前人研究成果的基础上，借鉴国内外先进经验和方法，利用自主设计定制的化学渗透试验装置（硬壁式渗透仪）及其他多种方法与技术深入研究咸水下移的内在机理，获得了华北平原典型咸淡水含水层间弱透水层粘性原状土和重塑土的化学渗透率系数分别为0.013和0.089。以此为基础，进一步建立华北平原典型咸淡水剖面上的连续模型对剖面上渗透压力的演化进行模拟，再现和讨论了人类活动影响下咸水下移的动力演变过程及影响咸水下移的主控因素，说明华北平原咸-淡含水层间的弱透水层普遍存在着化学渗透效应。最后，将数值模拟模型与优化模型相耦合,并通过研发各种进化算法，求解得到该区地下水资源的可持续利用模式。本项目研究在弱透水粘性土层中地下水的溶质运移理论和基于智能搜索的优化算法上均有突破，项目成果可为研究区域地下水资源可持续利用提供科学决策依据。