Revised Model for Finite-Difference Modeling of Flowing Artesian Wells
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摘要: 自流井是井孔-含水层系统的一种典型水文地质现象, 但在地下水资源评价和管理模型中研究较少.目前地下水数值模拟对自流井的3种处理方法均不合理, 也缺乏验证.常规地下水流有限差分法既不能准确地求出抽水井的井中水位, 也不能准确地求出自流井的流量, 必须进行校正.考虑自流井周围的径向流, 通过与井点附近地下水流的解析解相结合, 提出了矩形网格有限差分模拟的自流井校正模型, 其中考虑了自流井周围含水层存贮量的释放.算例表明, 即使用千米级大尺度网格, 本校正模型也能够获得相当精确的自流井流量, 绝大多数情况下相对误差小于5%.Abstract: It is a typical hydrogeological phenomenon for flowing artesian wells occur in aquifer-well systems. However, these wells have been seldom analyzed in the models for assessment and management of groundwater resources. The three treatment methods of flowing artesian wells that applied currently in numerical modeling of groundwater flow are unreasonable and are not verified. It proves that conventional finite-difference method can neither give accurately the water table in a pumping well, nor the flow rate of a flowing artesian well. The calculated head or flow rate of well-element must be revised. Applying analytical method, a revised model of flowing artesian wells is developed for finite-difference grid with rectangle cells, taking into account of the radial flow in the vicinity of an artesian well, and the release of storage in the confined aquifer surrounding the artesian well. Examples indicate that this revised model of flowing artesian wells gives a significantly improved numerical result of flow rate, with average relative errors less than 5% even for 1 000-m-magnitude cell size.
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Key words:
- groundwater /
- flowing artesian well /
- numerical modeling /
- finite-difference method.
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图 1 正方形差分网格示意图
Fig. 1. Schematic representation of finite-difference grid with square cells
图 2 不均匀矩形差分网格示意图
Fig. 2. Schematic representation of finite-difference grid with rectangle cells
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