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时间序列模型和有限元模型在地下水资源评价和开发中的应用——以徐州市裂隙岩溶水为例

吴剑锋, 朱学愚, 钱家忠   

  1. 南京大学 地球科学系, 江苏 南京 210093
  • 收稿日期:2000-09-20 修回日期:2000-09-20 出版日期:2000-09-20 发布日期:2000-09-20

A Time Series Model with Finite Element Method for Rational Exploration of Fracture-Karst Water Resources in Xuzhou City

Wu Jian-feng, ZHU Xue-yu, QIAN Jia-zhong   

  1. Department of Earth Science, Nanjing University, Nanjing 210093, China
  • Received:2000-09-20 Revised:2000-09-20 Online:2000-09-20 Published:2000-09-20

摘要: 针对徐州市地下水长期无节制开采和管理不善而引起的多种环境地质问题,建立了与研究区裂隙岩溶含水层相适应的地下水流模型,并运用有限元方法进行求解。考虑到大气降水的多寡及其分配状况是影响地下水资源的最终决定因素,同时建立了研究区大气降水的时间序列模型,并应用于评价该区地下水资源,从而在宏观上为徐州市合理开采裂隙岩溶水资源提供科学依据。其结果对我国其它类似地区地下水资源的合理开采具有指导意义。

Abstract: Xuzhou is an industrial city which extracts the largest amount of groundwater for water supply in Jiangsu province. Uncontrolled extraction from the fracture-karst aquifer has caused many environmental geologic problems, such as regional cones of depression, specific capacity decreasing in wells, groundwater quality deterioration, and karst collapse. With the development of the urban size and local economy, the water demand for the city will increase sharply. Therefore, rational utilization of groundwater resources is necessary and urgent for the Xuzhou City.   The research area covers five well-field districts. In this study, the five well fields are simulated as a unity. First, porous media model is applied to modeling the fracture-karst flow based upon a simplified conceptual model maintaining the key features of the research area. Then, Finite Element Method (FEM) is used to solve the corresponding mathematical model. The numerical simulation strictly follows the national standards of P. R. C. (GB/T 14497-93) Requirements for the Work of Groundwater Resources Management Model to guarantee the accuracy of study and increases the reliability. The results of modeling demonstrated that the theory of porous media model is suitable for the regions of fracture-karst in North China. In the previous studies, the average rainfalls or the frequency combination of precipitation were used to evaluate groundwater resources, which usually yield a result too conservative to exactly appraise groundwater resources. Therefore, in this study we employed a nonlinear time series model for precipitation in the research area, and apply the model to forecast the rainfalls in the cause of evaluating groundwater resources. We believe this measure could make a more accurate prediction.   According to the results of this research, which are compared with the actual statistical data of the current exploitation, the current extraction conditions of Xuzhou City are irrational.   Such irrationality lies not in that the current exploitation is over allowable groundwater yield on the whole, but that there is no scientific distribution of exploitation in each well field.   If the administrator adjust the existing exploitation conditions in accordance with our research results, the environmental geologic problems will be gradually resolved, and the present contradiction between water supply and water demand in the research area will not be further sharpened. This paper shall be of profound significance to solve the contradiction between water supply and water demand in the regions similar to the research area. Of course, the efficiency using the method of combining the time series model and FEM in the course of long-term groundwater resource evaluation should be verified in the further work.