| Jinci is the second biggest karst spring in Taiyuan City,and it is also an important source of water for local industry,agriculture and domestic water.As one of the most important coal base in China,Gujiao mining area is just located in the recharge area of Jinci spring,and because of its special geographical location,the coal mining activities in Gujiao mining area has had a major impact on Jinci karst water.With the increase of coal exploitation in Gujiao,the water bearing strata of coal bearing strata have been destroyed in varying degrees,and the mine drainage has become the main way of local groundwater discharge,which further aggravate the underground water level continues to decline in Gujiao karst,and the contradiction between supply and demand of local water resources has become increasingly prominent.The influence of coal mining on karst groundwater cannot be ignored,it is necessary to study the influence mechanism of coal mining on karst water in Gujiao area,and has a great significance both on regional water security and sustainable utilization of water resources.The main contents and conclusions of this paper are as follows:(1)Taking Gujiao mining area of Shanxi as the research object,on the basis of collecting and arranging a large amount of data in the study area,by analyzing the hydrogeological conditions,the types,occurrence conditions and distribution rules of the aquifer in Gujiao mining area were mastered,and the recharge sources and excretion pathways for each aquifer were identified.Based on the 3D visualization software GMS,the three-dimensional geological structure model of Gujiao was constructed,and the location relationship and hydraulic relationship between the karst aquifer and other aquifers in Gujiao were directly understood and analyzed.(2)On the basis of the analysis of the change mechanism of aquifer structure under the influence of mining activities and the composition of coal mine drainage and water filling,the effects of coal mining on the recharge,runoff and discharge of different aquifers in Gujiao area were discussed;Based on the hydraulic connection between the target aquifer and the other aquifers,the influence of coal mining on the recharge,runoff and discharge conditions of the karst aquifer in Gujiao were analyzed.(3)Based on the Data of 1975 ~ 1980,the groundwater simulation software GMS was used to generalize the hydrogeological conditions of the study area,and the numerical model of karst water in Gujiao without coal mining was established;By controlling the structure and parameters of the model to keep it unchanged,the measured data of the influencing factors of the karst water other than the coal mining factors were input into the model;Based on the data of groundwater level that has the actual measured information in 1985,2000 and 2009,the karst water level were simulated under the influence of no coal mining for three years,and by comparing with the measured water level,and combing with historical data of Gujiao coal mining,the influence quantity and lawof coal mining on karst water in Gujiao were analyzed.The results show that: under the influence of coal mining,the average karst water level in Gujiao decline of 7.42 m per year from 1980 to 1985,20.65 m from 1980 to 2000,and 29.71 m from 1980 to 2009;the average impact rate per ton of coal were 4.65m3/t,3.32m3/t,and 2.51m3/t respectively;it was proved that the influence quantity of coal mining on karst water in the simulation period in Gujiao was becoming larger and the influence rate was decreasing. |
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