| Taiyuan is a serious water shortage city, which is the 1/12 of the quantity per capita in China. The study on the construction of Xizhang groundwater reservoir is significant for solving water resources spatiotemporal maldistribution, improving water resources utilization efficiency, ameliorating region ecological environment, ensuring society and economy sustainable development in Taiyuan.Through analyzing hydrology, weather, topography and geomorphology, areal geology, hydrogeological conditions and other geologic environment conditions in Taiyuan Xizhang Basin, the results show that Xizhang Basin is influenced and controlled by geologic structure and stratum lithology, the three plane of water-storing structure is recharge boundary, and the south is the Sangei horst fault, water storage space is loose Quaternary deposits, the thickness of water storage layer is big and steady, the groundwater storage space is big, the aquifer lithology is mainly gravel, specific yield is bigger, storage regulating is considerable; Xizhang Basin has certain recharging condition and mining measures, and has the fundamental condtions of groundwater reservoir construction.According to the geologic structure, storage conditions of the aquifer and movement characteristics of Xizhang groundwater reservoir, the conceptual model of hydrogeology and numerical model of the groundwater was developed. The model was calibrated and verified by using Visual MODFLOW software. The research results showed that the mathematical model, the boundary conditions and hydrogeological parameters conform to the reality; the modle can be used in dynamic simulation and forecasting of reservoir water level. Regional water balance is demonstrated that during simulation period in reservoir area, the water changed volume of aquifer is positive equipoise and infiltration of precipitation takes a chief part in total recharge, while pumping is a main discharge.According to stratum boreholes of research area, geological structure graphs and section drawing were drawed, the characteristic parameters of water level and capacity of groundwater reservoir area was analyzed and computed reasonably. The research results showed that the maximum storage capacity of unconfined aquifer was 526.3 million stere, the minimum storage capacity of confined aquifer was 175.4 million stere and the maximum rational regulating storage space of unconfined aquifer was 350.9 million stere.The effects of impervious wall on variation of groundwater flow field was simulated at the horst fault of Sangei by HFB in Visual MODFLOW, the results show that the lateral discharge of groundwater is 8.199 billion stere per year under no impervious wall treatment, the rising of groundwater level was smaller during simulation period; lateral discharge decreases with the increase of the thickness and decrease of hydraulic conductivity of impervious wall at the Sangei horst fault. When the thickness was 0.5m and hydraulic conductivity was 0.01m/d of impervious wall, the lateral discharge was 3.58 billion stere per year and was 47.3% of no impervious wall treatment, and that scheme was the optimum scheme of impervious wall construction. The research results would provide with technical support for building mothball water resources of Taiyuan, and planing and construction of Xizhang groundwater reservoir. |
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