Analysis Of The Influence Of Strip Mining On The Groundwater Environment In Xiwan, Shaanxi

Xiwan opencast coal mine is located in northern Shaanxi, which is the arid and semi-aridarea. The ecological environment is very fragile. The two main characteristics of this area arethe serious shortage of water resource and the relative abundance of mineral resources. Inrecent years, with the gradual implementation of develop-the-west strategy, the mineralresources exploitation and its related industries are developing flourishingly. On the one hand,the actual water consumption is increasing rapidly; on the other hand, mineral developmentwith its related industries has been a serious threat to local water resource whether for thequality or for the quantity. Therefore, it’s necessary to predict the groundwater environmentalchange in the situation of mineral resources exploitation and to provide technical andtheoretical support for the sustainable development in this region.In this paper, hydrogeological conceptual model, three-dimensional geometric model andthree-dimensional hydrogeological model was established based on the geological conditions,the hydrogeological conditions and the current situation of groundwater environment wasascertained in detail in the study area. Based upon these models, the situation of gush-outwater, the changes of groundwater level and flow distribution were simulated under twodifferent situations:“no protective measures are taken when exploration begins” and “100mimpermeable coal pillar is reserved when exploration begins”. According to the simulationresults, the influences to the groundwater dynamic field and various types of water sources,which result from the strip mining, and the groundwater environment after the open pit minehas been closed were both analyzed in detail.The following conclusions were summarized in this paper:1. When no protective measures were taken, the scope of the unwatering area isrespectively large on the east where the burning rock distributes: The range in whichdrawdown is greater than0.1m is6000~10700m, and in which drawdown is greater than1m is5200~~10300m. The scope of the unwatering area is relatively small on the west: Therange in which drawdown is greater than0.1m is1300~3500m, and in which drawdown isgreater than1m is680~1100m. The gush-out water in every mining area are of great quantity, and in the initial stage of strip mining, the quantity is reach up to22929.10～66081.20m3/d.2. After the protective measure that “100m impermeable coal pillar was reserved beforestrip mining” was taken, the scope of the unwatering area did not change significantly, but thewater level decrease in strip mine have been significantly reduced. Groundwater level declinein most of the region is less than1m, and only in relatively small area rounded the open pit ismore than5m. In the same time, the quantity of gush-out water is significantly reduced. Takethe first mining area for example, this measure decline the rate of gush-out water by90.43%.