Study On The Relationship Between Rainfall And Groundwater Varies In Different Karst Areas

In recent years,due to a series of policies such as the shut-in and pressure mining and so on,the Lancun spring water level shows a gradual upward trend,and new changes have taken place in the dynamic types of groundwater.Therefore,this paper mainly analyzes the relationship between rainfall and karst groundwater level by studying rainfall and different types of karst areas(including exposed karst area,covered karst area and buried karst area).The bare area takes Lancun Water Plant and Liulinhe area as an example;the covered area takes Siuxi Village as an example;the buried area takes Yinjiagou Village and A0 borehole in Gujiao City for example,conducts annual dynamic and annual The dynamic changes of the dynamic water level and rainfall are analyzed to analyze the influence of rainfall on the water level.Finally,using the spass regression model to simulate the effect of rainfall on groundwater in different types of areas,and draw the corresponding regression equation.The results show that:(1)The water level in bare karst area is significantly affected by rainfall.The rainfall in this area is positively correlated with the groundwater level.When the rainfall is less than 50 mm,the rising rate of water level increases with the increase of rainfall.When the rainfall exceeds 50 mm,The rate of rainfall infiltration slowed down and the rate of change of water level obviously slowed down.During this period,the water level as a whole increased and the lag time of water level was about 2 months.(2)There was still a positive correlation between karst water level and rainfall in the coverage area Hysteresis is longer: for a long period of time,the water level rises slowly due to the formation of surface runoff in the loess area after rainfall,which leads to the formation of rainfall load and pore water pressure,resulting in the slowdown of rainfall infiltration rate After the second replenishment,the water level increased rapidly and the lag time was about 4 months.(3)There is a positive correlation between the karst groundwater level and the rainfall in the buried karst region,and the lag time is longer than that of the covered and bare types,about 6 months.When the rainfall is 25 mm,the rainfall directly infiltrates the groundwater and the water level reflects more rapidly.When the rainfall exceeds 25 mm,the water level will react slowly.In addition,sampling and analysis of karst water in different regions of the same time period were carried out.The water samples were classified according to Shukarev classification and piper three-line diagram.The water quality of the three different types of karst areas did not change much.SO4-Ca-type water,other regions are HCO3-Ca-type water.Finally,through the method of composite index,the water quality is divided.The result shows that,Lancun spring area of various types of water quality are at a good level.