Self-potential Features Of Groundwater In Epikarst Zones In Guangxi And Application Research Of Water Exploration

In karst areas in southwestern China where lives over 100 million people,the special geologic setting results in a serious loss of precipitation.The shortage of water resources is one of the major factors leading to poverty and backwardness in some karst regions.Based on the hydrogeological characteristics of this region,including the complex structure of epikarst zone,the highly non-uniform water enrichment,the shallow buried groundwater,and the abundant and easy-to-exploit water resources when hydrogeological conditions are favorable,it is urgent to develop the detection methods with strong anti-interference ability,high signal-to-noise ratio and suitable for the investigation of surface karst groundwater resources in water deficient karst areas in southwest China.Towards this end,this study chooses the karst areas in Guangxi as the research object and studies the exploration method of groundwater in Epikarst zone with the support from the National Natural Science Foundation.This study focuses on the features and application of self-potential detection of groundwater in Epikarst zones.The research result is of great practical significance to promote the research of groundwater detection method in karst area and alleviate the contradiction of water shortage in people's life and production in karst area.This work analyzes the characteristics and migration regularity of underground water hosted in dissolution-crack networks in Epikarst zones in depressions and peak-cluster valleys in southwestern China,especially in Guangxi.Based on the similarity and analogy theory in geology,the variations of self-potential curve of polarization balls with different radii and at varied burial depths are calculated,to study the characteristics of self-potential produced by groundwater seepage and migration in Epikarst zone and the method of detecting groundwater in Epikarst zone with self-potential method.Through the first-order central difference quotient theory,this project studies the difference filtering methods for the local horizontal gradient signal anomaly of self-potential,and applies it to the data processing method for self-potential that is weak or interfered to some extent,to attain effective separation of local useful self-potential anomalies of water rich dissolution gap in karst zone Based on self-potential measurements at varied depths and different seasonal times,this project studies the 3D imaging method for the occurrence probability and the time-space change features of the anomalous charges of weak self-potential produced by underground water flow in Epikarst zones in karst depressions,and successfully applies the 3D imaging method to in situ identifying the best position of groundwater development and utilization in karst depression and peak cluster valley area in the Epikarst zones.It provides a practical method for further researches on seepage migration regularity of underground water in Epikarst zones.By this way,the effective anomalies are highlighted and the features of self-potential anomalies of dissolution water-rich cracks in Epikarst zones are clarified,indicating that the processed self-potential data can effectively facilitate identifying water-rich dissolution cracks.Furthermore,through a combination of the self-potential method and high-density electronic method,the spatial distribution of water-rich dissolution cracks in Epikarst zones can be revealed from vertical and horizontal directions.The methods presented above have been employed in the practice of underground water exploring in the Epikarst zones in karst depressions and peak-cluster valleys in Gongcheng county of Guilin,Luzhai county of Liuzhou,and Longzhou county of Chongzuo,all in Guangxi province.Results reveal that using the established self-potential data processing technology aided by the high-density electronic method,can lower the possibility of multiple-solution of a single method.This study successfully identifies karst water-bearing cracks and enhance the well-completion ratio.It shows the advantages of short field construction period,simple operation and high well-completion rate,which has great popularization potential in detecting groundwater resources in the karst zones of Guangxi and even other karst areas in southwestern China.It has made a contribution to reducing the water-shortage situation,alleviating the problems caused by water resource insufficiency,and advancing the development of society and economy in karst regions,attaining good social and economic benefits.The application of the differential filtering method for self-potential horizontal gradient data can effectively separate the local anomaly of self-potential horizontal gradient from the regional background field,suppress the interference signal and highlight the effective anomaly.The application of self-potential charge 3D probability imaging method can in-situ identify the dominant seepage channels of groundwater in different time and space in Epikarst zone,which provides a practical method for further research on the law of groundwater seepage movement in Epikarst zone.The combination of self-potential method and high-density electrical method,supplemented by the differential filtering method of self-potential horizontal gradient data,establishes the detection method system of groundwater in the surface karst zone,which reduces the possibility of multi solution of single detection method and improves the well completion rate.