Study On Identification Of Shallow Hydrogeological Structure And Influence Of Coal Mining And Drainage In Xilin River Sub-basin,Inner Mongolia,China

China is a coal dominated energy country.The exploitation and utilization of coal resources not only promote the great development of the economy,but also have a great impact on the geological environment.Groundwater,as a receiver of geological environment changes and a carrier of information,plays an important role in indicating the extent and scale of changes in the geological environment.The exploitation of open-cast coal will inevitably cause the decline of groundwater level and the continuous expansion of the funnel,thereby changing the recharge,runoff and discharge conditions of groundwater system.In the end,the deterioration of the geological environment and the ecological environment,such as the decrease of the river runoff,the shrinking of the lake area,the quickening of the desertification trend of the grassland,etc.Inner Mongolia has become the forefront of the development of coal resources in China,in which Xilin Gol Grassland has become a new base of Beijing-Tianjin Energy due to its rich coal resources.Although Xilin Gol Grassland is rich in coal resources,it is seriously deficient in water resources and its groundwater environment is very fragile.Especially Xilin river sub-basin is a typical representative.More attention should be paid to the impact of groundwater when developing coal resources.This puts forward higher requirements for deep excavation of groundwater system response mechanism on the influence of coal mining and drainage.However,the hydrogeological data is not enough.The traditional hydrogeological survey method has serious damage to grassland ecological environment.This has become a very prominent issue that seriously restricts the rational development and utilization of coal resources in the basin.Therefore,how to break through the limitations of traditional hydrogeological survey methods and establish a non-invasive and highly accurate identification method for hydrogeological structures.It has become a top priority for the rational development and utilization of coal in such areas where groundwater environment is relatively fragile.This research takes the Xilin river sub-basin as the research area.A new non-invasive joint identification method for hydrogeological structures by MT-SNMR is carried out starting from the inversion interpretation of magnetotelluric method(MT)and surface nuclear magnetic resonance(SNMR)method.The shallow hydrogeological structure of Xilin river sub-basin is identified by MT-SNMR.The accuracy of identification is verified by the actual borehole data,and the identification efficiency is much better than the traditional hydrogeological survey method.The MT-SNMR identification results can effectively make up the serious shortage of hydrogeological data,and have important reference significance for the areas with relatively fragile environment and serious lack of hydrogeological data.A water rich evaluation method of aquifer based on AHP-SNMR information fusion is proposed based on the MT-SNMR identification analysis of hydrogeological structure and multi-objective decision theory.This method effectively solves the problem of serious lack of hydrogeological data in water rich evaluation and plays an important role in guiding the evaluation of water resources in this area.The first response model of different recharge sources and discharge amounts of the groundwater system is constructed in the Xilin river sub-basin.In view of the influence of coal mining and drainage on groundwater system,the simulation and prediction are carried out.The spatial and temporal evolution mechanism of groundwater flow in the study area is revealed.This paper emphatically analyzes the serious consequences of wanton dredging aquifer on geological environment and provides scientific basis for restoration and treatment of mine geological environment,ecological environment protection and groundwater restoration in grassland area.Coal mining has drained groundwater and robbed surface water resources.In order to clearly define the effect of coal mining and drainage activities on surface water,the Mann-Kendall mutation test is used to divide the changes in surface runoff and lake area into base period and influence period and YRWBM model is used to quantitatively analyze the influence of human activities such as coal mining and climate change on surface water.The effective application of the three methods has solved the definition of the reference period of hydrometeorological series and the restoration of natural runoff during the impact period.Therefore,it provides a powerful research method for revealing the hydrological evolution mechanism of the basin under the stress of coal mining.The influence of coal mining activities on water resources is a complex process in which human activities and natural environmental changes are intertwined.It not only needs to establish a comprehensive and effective research method and evaluation system,but also needs to introduce a series of measures and countermeasures for water resources restoration and compensation under the strong intervention of coal mining activities.Multi-disciplinary and multi-level measures are of great theoretical and practical significance for alleviating the crisis of grassland water resources and promoting the sustainable development of prairie coal economy and ecological environment.