长时间尺度的京津冀平原区地下水动态模拟及演变特征

Dynamics and evolution of the groundwater in Beijing-Tianjin-Hebei Plain in a long time scale

地下水资源是京津冀平原的主要供水水源,自上世纪60年代以来,平原区地下水资源和地质环境显著地受到了人类活动和气候变化的影响,而地下水位动态是对人类和自然等影响的直接响应。针对于多因素作用下的平原区地下水位动态,文中基于水文地质条件分析和观测孔水位数据分析,综合利用数值模拟方法重现了平原区长时间尺度的不同空间尺度(全区、典型地段)下地下水位演变过程,揭示了平原区地下水水位动态机制。结果表明:近50年,全区平均地下水位持续下降,下降速率为0.36m/a;大面积浅层降落漏斗形成,石家庄漏斗中心水位下降速率最快,为1.1m/a;2001~2010年地下水平均补给速率(154.97mm/a)比1961~1970年减少6.2%,地下水更新能力明显减弱。地下水开采强度常年多于补给资源,导致了不同空间尺度上地下水位的下降,开采是影响地下水动态的主导因素,降水是限制地下水补给更新的主要因素。在气候变化和人类活动的双重影响下,平原区未来供水安全仍会面临挑战。

Groundwater is the main source for water supply in Beijing - Tianjin - Hebei Plain. Groundwater resource and geological environment have been influenced by human activities and climate change. Groundwater dynamic is a direct response to human and climate, so the groundwater level changes in different special scales for a long time span were analyzed by the method of numerical simulation based on the hydrogeological settings and observation wells data. Moreover, the groundwater dynamic mechanism was revealed. Results suggest that groundwater level had declined continuously with a rate of 0.36m/a. Large shallow groundwater cones of depres- sion had also formed, among which Shijiazhuang cone groundwater level declined the fastest with the rate of 1. l m/a. The renewability of groundwater changed obviously with mean annual recharge rate during 2001 -2010 （154.97mm/a）, decreased by 6.2% compared with that in 1961 -1970. The exploitation rate was exceeding the precipitation recharge rate which caused the groundwater level declined in different special scales. Exploitation was the main factor for groundwater dynamic while precipitation was the limiting factor for groundwater renewability. Water supply will face challenges for Beijing -Tianjin -Hebei Plain in the future.