连续干旱对北京平原区地下水的影响

Effects of continuous drought on groundwater in Beijing plain

北京水资源主要由地表水和地下水资源组成,其中地下水供水量约占水资源开发利用总量的三分之二,显而易见地下水资源在北京城市可持续发展中起着尤其重要的作用。北京地区经历了1999—2011年连续12年的干旱。干旱对地下水资源有直接的影响,即减少了自然补给。同时,干旱增加了应急供水需求,导致了地下水开采量增加。分析了北京平原地下水资源及变化特征,应用标准化降水指数分析了近50年北京平原的干旱时间分布特征,建立并运用非稳定地下水模型分析了干旱对地下水资源储量消耗的直接和间接影响。研究显示干旱加速了地下水资源储量消耗和地下水位下降,在潮白河和永定河冲洪积扇尤其明显。为实现地下水可持续开发利用,必须采取措施控制地下水开采,增加地下水补给。针对北京市干旱发生状况和发展趋势,提出了应对干旱的管理措施。

Water resources in Beijing mainly include surface water and groundwater. Groundwater supply accounts for two-thirds of water supply for Beijing municipality, and groundwater resources play a fundamental role in the sustainable development of Beijing municipality. Beijing has suffered a long dry spell of 12 years from 1999 to 2011. The drought has a direct impact on groundwater resources by reducing natural recharge. The drought also led to the increase of groundwater abstraction for emergency water supply. The change characteristics of groundwater resources in Beijing plain are discussed in this paper. The temporal characteristics of drought of Beijing plain in recent 50 years are analyzed with standardized precipitation Index （SPI）. A transient groundwater flow model was established and used to analyze the direct and indirect impacts of the drought on the depletion of groundwater storage. The results indicate that the drought has accelerated the depletion of groundwater storage and the decrease of groundwater levels, especially in the alluvial-proluvial fans of Chaobai River and Yongding River. To realize sustainable development and utilization of groundwater, some actions must be taken to increase the groundwater recharge and reduce groundwater exploitation. Based on the current situation and the trend of the drought in Beijing, some management measures on relieving the impact of drought are put forward.