| The karst area is rich in groundwater resources and has great development potential.However,the underground distribution structure in karst area is complex,with strong heterogeneity,and the law of flow movement is changeable.Special hydrogeological conditions limit the use of groundwater resources.This study takes the Haiyang-Zhaidi groundwater system in the Li River Basin of Guangxi as the research object.In this study,the water balance observation network of the groundwater system is set up,and the system is divided according to observation data and hydrogeological characteristics survey.The moving average method,Sen's slope estimation method,Kendall rank correlation test method are used to calculate the precipitation variation characteristics of the system,and analyze the conversion characteristics of the groundwater resources to evaluate the natural groundwater resources of the system.The research established an appropriate evaluation system of groundwater resources in karst areas,which provided a scientific basis for the development and evaluation of karst groundwater resources.The main research results are as follows:1.According to the hydrogeological survey,the Haiyang-Zhaidi groundwater system is divided into 7 subsystem:Diaoyan Underground Water System,ShuiNiuyi Underground Water System,DongJiuxi Underground Water System,DongJiudong Underground Water System,Dafu Underground Water System,ChangPuling Underground Water System,Zhaidi Underground Water System.The characteristics of groundwater subsystem replenishment,diameter,and discharge provide a research basis for the dynamic change characteristics of karst groundwater resources in the study area.2.The precipitation trend of the Haiyang-Zhaidi groundwater system during the wet season is obvious,the rate of change is 4.11 mm/a.The annual precipitation decline trend is relatively slow in the flat water period,the rate of change is 1.97 mm/a.The precipitation trend of the system during the dry season is slow,The rate of change is 2.32 mm/a.The abrupt years of the Haiyang-Zhaidi groundwater system during wet season,the flat water period and the dry season are 2001,1996 and 1993 respectively.The precipitation during the system's wet season did not change significantly in 1996 and 2001;The precipitation in the system during the wet season did not change significantly in 1996 and 2001;the precipitation in the system during the flat water period did not change significantly in 1977,1980,1984,1986,and 1997;The precipitation during the dry season did not change significantly in 1994.3.The water resources conversion of the Haiyang-Zhaidi groundwater system is mainly underground runoff.System replenishment is mainly infiltration of atmospheric precipitation.Precipitation infiltrates into the karst zone through the soil belt,and the form of runoff is mainly pipelines and fissures.Part of the water flows through the bedrock fissure and forms an overflow spring.Part of the water flows through the karst pipeline to the underground river outlet.During the wet season,the pipeline is filled with water to replenish the bedrock fissure water.During the dry season,the water level in the pipeline is lower than the surrounding aquifer,and the bedrock fissure water supplements the pipeline water.The form of excretion is mainly surface karst spring,karst spring,groundwater outlet,etc.The relationship between system flow,water level and precipitation response is obvious,and the seasonal variation is strong.4.Recharge coefficient of precipitation infiltration?changes with time and space.Recharge coefficient of precipitation infiltration?of the system calculation period were 0.648,0.483 and 0.337 respectively.The natural resources of groundwater in different calculation periods of one hydrological year in the system are 324.37192 million m~3,4.75702 million m~3,and 2.798199 million m~3.The rapid flow of the Haiyang-Zhaidi groundwater system is linearly related to the total groundwater runoff.The slow flow has a quadratic function relationship with the total underground runoff.Based on the identification of the karst hydrogeological conditions in the Haiyang-Zhaidi groundwater system,we can realize the effective use of rapid-flow water resources by artificially plugging and storing large underground rivers and karst springs. |
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