摘要:
为深入研究北京平原地下水资源的现状及未来的变化趋势,探讨地下水资源可持续开发方案,文章建立了北京平原三维地下水流非稳定流模型。在充分分析北京平原区水文地质条件的基础上,建立了三维数字水文地质概念模型。从区域上将北京平原含水层系统划分为5个含水层和4个弱透水层互层的多层系统。在此基础上利用GMS模型软件建立了三维地下水稳定流模拟模型和非稳定流模拟模型。首先利用1995年丰水年的地下水均衡量建立和校正了稳定流模型。之后在稳定流模型的基础上建立和校正了非稳定流模型,非稳定流模型的模拟期为1995～2005年。最后用模型分析了北京平原区地下水流场的变化趋势。与20世纪60年代天然流场相比,北京市平原区区域地下水流场发生了巨大变化。除了区域地下水位整体下降外,在不同深度的含水层形成了规模不等的地下水位降落漏斗。自1999年以来的连续干旱,导致河流基本干枯,地下水补给量减少,加之应急水源地的投入运行,使地下水贮存量被持续地大量消耗,地下水位快速下降。长期以往,必将造成含水层地下水疏干。控制和减少地下水开采势在必行。
Abstract:
A 3D transient groundwater flow model was established for Beijing Plain.The purposes of the model are to analyze current status and to predict future trends in groundwater resources.The model will be used also to simulate various groundwater resources development scenarios.A digital hydrogeological conceptual was constructed using all sorts of spatial and temporal data.A quasi steady state model was calibrated using the average values of water balance components in 1995 when groundwater levels show an equilibrium state.The steady state model created the initial conditions for a transient model.The transient model simulation time is from 1995 to 2005 with month as stress period.The transient model was calibrated against measured groundwater level series.The calibrated model was used to analyze groundwater flow systems and water balance.Compared to the 1960s,decline of groundwater levels occurred regionally,cone of depressions has been formed in aquifers of different depth.The consecutive drought years from 1999 to 2005 has caused dry rivers and reduced groundwater recharge.Operation of emergency well fields to meet demand of urban water supply has accelerated the decrease of groundwater levels.If current situation continues,groundwater in Beijing Plain will be depleted,a reduction in abstraction is urgent to achieve long-term groundwater sustainable development.
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