| The piedmont area of Jiaozuo City is a concentrated runoff-discharge area of the karst water system of the Jiulishan Mountain.The karst water resources are abundant and the water quality is good.It is the main source of water for the city.Since the 1950 s,urban extraction and mine drainage have been the main excretion methods for karst water.Especially in the 1980 s,only the total drainage volume of coal mines was as high as 8.5m3/s,resulting in a drop in karst water levels.After 2011,the mines owned by factories and mines were closed one after another,and some coal mines were closed down due to the depletion of coal resources.The amount of karst water mining decreased and the water level rose.Jiaozuo City,as national water ecology civilized city construction pilot,is building a landscape garden city transformation.Under the combined influence of reducing drainage in the coal mines and reducing the amount of mining in the city,how did the karst water level change and whether the historical Jiulishan spring group can resurrect? Urban builders are very concerned about the issue.Based on a comprehensive analysis of the hydrogeological conditions of karst water in Jiaozuo mining area,this paper systematically studies the dynamic changes of water level,and analyzes the influence of urban karst water and mine drainage on water level.Using the grey correlation analysis method,the degree of correlation between water level,rainfall,and extraction volume was studied.Using sliding average method and Mann-Kendall non-parametric statistical method,the trend of the karst water level,rainfall,and extraction volume since 1965 was analyzed.Based on the analysis of the main influencing factors of karst water levels,the comprehensive The geological conditions and hydrogeological conditions in Jiaozuo mining area were analyzed,and a conceptual model for the hydrogeology of Jiaozuo karst water was established.Visual Modflow software was used to establish a numerical simulation model for predicting the karst water level in Jiaozuo mining area.After parameter identification and model inspection,the model conformed to the actual hydrogeological conditions and was stable and reliable.Applying the statistical models and numerical simulation models constructing,the prediction of water level changes under conditions of reduced drainage in the coal mines and reduction of mining volume in the city is predicted.Research shows that since 1965,the precipitation in the Jiaozuo mining area has not shown a significant downward trend,and the multi-year fluctuation of the karst water level is not due to the reduction of precipitation infiltration recharge,which is mainly related to the increasing urban mining volume and mine drainage volume.The numerical simulation and prediction show that the karst water level in the Danhe seepage section in the western part of the mining area is controlled obviously by precipitation.After the Fangzhuang Mine and the Yanma Mine are closed to stop drainage,the karst water landing funnel will gradually disappear.After the Zhucun Mine,Fangzhuang Mine,and Yanma Mine closed and stopped drainage and the amount of urban mining was reduced,the karst water level will decline slightly in the next three consecutive years,with a total drop of 3 to 8m.At the time of year,the water level in the western part of the mining area increased by 5-10 m and in the middle and east by 2-5m.In the continuous flood year,the water level of the karst water increased significantly,the maximum increase was 20 m,and the eastern and middle parts of the mining area increased by 5-11 m.After the closure of the Yanma mine,there will be a 3-4 month rise in the nearby water level,after which the normal year-on-year fluctuations of karst water will be restored;in the abundant rainfall years,the Jiulishan karst water level will reach 92.1m at the highest.Jiulishan spring group is expected to resume. |
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