基于多源数据分析的洼里砾岩地下水循环特征

Analysis of Groundwater Circulation Conditions of Wali Conglomerates in Beijing Area based on Multi-source Data

利用钻孔、地下水位、水质、温度和同位素等多源数据,识别了洼里地区的地质结构、地下水动态、地下水化学、地下水温度和同位素特征,分析了洼里砾岩与奥陶系、第四系含水层的水力联系。洼里砾岩在西部与奥陶系地层直接接触,与奥陶系含水层存在水量交换通道;洼里砾岩与奥陶系和第四系地下水水位具有一致的年际和年内变化特征,水位高值一般出现在1—2月,水位低值出现在5—6月。同时,洼里砾岩、第四系和奥陶系地下水水化学类型均为HCO3-Ca·Mg型,且C-14和S-34同位素值相近,地下水温度变化规律具有区域一致性。结果表明,洼里砾岩岩溶发育,富水性好,与奥陶系和第四系含水层水力联系密切。地下水循环特征表现为:地下水主要接受西部奥陶系地下水补给,自西南向东北方向径流,主要排泄方式为侧向径流和向第四系含水层越流。

This paper analyzed the hydraulic connection between Wali conglomerates and Ordovician, Quaternary aquifers from the aspects of geological structure, groundwater dynamics, groundwater chemistry, groundwater temperature and isotope characteristics. For Wali conglomerates directly contacting with the Ordovician limestones, there are water exchange channels. The interannual variability and variation during the year of groundwater table of Wali conglomerates and Ordovician, Quaternary aquifers are consistent. High groundwater table generally appear in the January and February, the low groundwater table appears in the May and June. Meanwhile, the groundwater in the Wali conglomerates, Quaternary, Ordovician belong to HCO3-Ca·Mg type, and the C-14 and S-34 isotope values are similar, and the regional groundwater temperature are consistent. The results indicate that karst is developed in Wali conglomerates with rich water resources. Groundwater circulation characteristics show groundwater recharge mainly from Ordovician groundwater, and runoff from west to east, the main way of discharge is lateral runoff, and the way of recharge is cross-flowing to Quaternary aquifers.