张掖市甘州城区及外围地下水位上升原因分析

采用传统的水均衡方法及环境同位素分析、氟里昂测年等技术,结合地震、地面物探、气象水文及地下水流场分析手段,分析了甘州城区及其外围地下水位上升的原因。结果表明:实施"黑河流域节水灌溉综合治理工程"引起水资源利用分配格局的变化不是引起地下水位大面积上升的原因;水位上升区第四系深层承压水与祁连山基岩裂隙水具有相同的水文地球化学特征和环境同位素特征。其结论:张掖盆地中心地带基底存在与祁连山区相连的北西向深大断裂带一直存在少量,且稳定的地下水越流补给量;自2003年10月山丹、民乐发生大地震以后,使得祁连山山前及盆地内基底断裂活动加剧,同时断裂活动错断了第四系松散层内的隔水层,基底断裂带变为导水通道,加快了祁连山区基岩裂隙水沿着这个通道向上越流补给盆地第四系孔隙水的速度,增大了越流补给量,使盆地地下水补给量大于排泄量,造成地下水位大面积上升。

Study on the Causes resulting in Groundwater Level Rise in Ganzhou City and Its Peripheral Regions

In this paper,the causes resulting in the groundwater level rise in large area in Zhangye City and its peripheral regions are preliminarily analyzed by applying the traditional water balance method and some advanced means,such as the environmental isotope analysis and CFC dating,based on the available data of earthquake research,geophysical prospecting,hydrogeology,meteorology,dynamic change of groundwater level,etc.The results show that the change of distribution pattern of water resources due to implementing the "Project of Water-saving Irrigation in the Heihe River Basin" is not the cause resulting in the groundwater level rise in large area;the hydrogeochemical and environmental isotope features of Quaternary confined groundwater in the regions with groundwater level rise in Zhangye are the same with those of bedrock crevice water in the Qilian Mountain.The conclusions are that the confined groundwater recharge in the Zhangye Basin is related to bedrock crevice water in the Qilian Mountain,and such linkage is strengthened under the effects of bedrock crevice water flow,groundwater flow,neotectonic movement and fault occurrence.