超采对北京市潮白河冲洪积扇中上部地区地下水质的影响

Effect of Over-exploitation on Underground Water Quality in the Upper Part of the Chaobai River Alluvial Fan in Beijing

潮白河冲洪积扇中上游地区作为北京市最主要地表水和地下水供给区,在城市供水中的作用举足轻重。由于多年连续超采,地下水位持续下降,1999—2013年地下水位下降最大达45 m;应急水源地地区地下水硬度年均上升2.6%,密云十里堡地区地下水硬度和硝酸盐氮超标。通过分析潮白河冲洪积扇区域地下水开发利用、地下水位和水质变化情况以及地下水位变化对地下水水质的影响,认为:超量开采导致的地下水水位下降是引起该区域地下水水质恶化的主要原因之一,控制地下水超量开采和地表水污染,并利用南水北调的水进京之机回灌和停采以涵养地下水,是恢复区域水资源和水环境的良好途径。

The middle and upper reaches of Chaobai River alluvial fan supplies the most surface water and groundwater to Beijing,and it plays an important role in the urban water supplies.The water level decreased because of groundwater over-exploitation for years,and lowered up to 45 m in some areas.Total hardness of groundwater in the emergency water resource area increased at average rate of 2.6% annually.Contents of total hardness and nitrate exceed the criterion of Shilipu area in Miyun.This paper analyses the development and utilization of groundwater in Chaobai River alluvial fan,the changes in groundwater level and water quality,and effect of groundwater descending on water quality variations.It is concluded that over-exploitation is the main inducing factor of groundwater quality deterioration of the Chaobai River alluvial fan in the middle and upper reaches.Controlling surface water pollution and groundwater over-exploitation,then using south-to-north water to recharge groundwater and decreasing exploitation is a good way to restore water resources and environment.