大沽河拦河闸坝影响下平原区地下水资源评价

The Effect of Rubber Dams and Sluices on the Groundwater Resources Estimation of Dagu River Plain

近年来大沽河干流上新建和加固拦河闸坝,对河道进行疏浚挖泥挖沙,河床下弱透水层变薄,甚至有的河段无弱透水层,河流直接补给地下水,这都会使大沽河地表水对地下水的补给量发生变化。本文根据大沽河调水实测资料,建立了大沽河平原区地下水数值模型,利用模型计算了大沽河对地下水的补给量,并预测了连续丰、平、枯水年的地下水资源量。研究结果表明:河床下存在弱透水层的河段,入渗补给初期河流补给量较大,随着地下水位上升,入渗补给量逐渐减小;直接补给地下水的河段河流迅速补给地下水,补给量很大,之后河流水位与地下水位相差很小,河流补给量很小。在现状开采条件下,改增建拦河闸坝后,丰、平和枯水年河流对地下水的补给量比之前分别增加了135%、123%和100%,地下水可开采量分别为11 722×104、9 338×104和8 219×104 m3/a。

Many rubber dams and sluices were built on the main channel of the Dagu River recently.In the construction,there became the thinner aquitard,or even no aquitardunderneath the riverbed where the river recharged the groundwater directly,which made the river recharge change.In this study,the groundwater flow model of the Dagu River Plain was developed by the use of the observed data from a water diversion.The model calculated the river recharge and estimated the groundwater resource in 5years under higher,normal or lower flow year conditions respectively.Simulated results showed that the river recharge declined gradually with the groundwater level increasing,when the aquitardexisted underneath the riverbed.The river recharge decreased sharply from a large magnitude when the river recharged the groundwater directly,then it became small because of the little gap between the river and groundwater level.The river recharge to the groundwater increased by 135%,123%,100%in higher,normal and lower flow years,respectively.The allowable groundwater exploitations were 11 722×104 m3/a,9 338×104 m3/a and 8 219×104 m3/a in higher,normal and lower flow years,respectively.