Study On The Differences Of The Formation Conditions Of The Four Spring Groups In Jinan

The karst area in Jinan is widely distributed,forming many large water sources and karst springs with strong regulating function and high water-rich degree.In recent decades,due to the combined action of natural and human factors,the fragile karst water system has deteriorated,and environmental hydrogeological problems such as karst water pollution and large karst spring failure have occurred.Although artificial replenishment measures have been taken to maintain the continuity of spring water Eruption,but the protection effect of Jinan's karst springs is not ideal.The fundamental reason is the lack of deep understanding of the formation conditions of the four major springs.To this end,this paper takes Jinan's four major spring groups as the main research objects.Based on a comprehensive investigation and analysis of Jinan's spring area geology and hydrogeology,the results are obtained through spring and groundwater dynamic monitoring,tracer tests,and hydrochemical tests.The data of the sequence,using spring flow attenuation analysis,frequency spectrum analysis,and isotope dating to study the differences in the formation conditions of the four major spring groups in Jinan,revealing the differences in the replenishment,runoff and discharge characteristics of the four major spring groups.The main conclusions are as follows:(1)The groundwater in the outcropping area of the spring group gushes out of the surface through the Quaternary gravel deposits.Based on comprehensive analysis,the geological age of the spring water is 8200?7490 a BP.Due to the distribution characteristics of intrusive rocks,the spring water types of Zhenzhu Spring and Tanxi Spring are classified as igneous rock fragmentation contact karst springs;while the outcrop of Heihu Spring and Baotu Spring is limestone skylight,and the spring water type is limestone skylight contact karst spring.,It can be seen that there are obvious differences in the genetic models of the four spring groups.(2)Based on the analysis of dynamic long-series precipitation and spring flow data,it is shown that the four major spring groups in Jinan are mainly recharged by precipitation on a macroscopic level,but there are obvious differences in the recharge sources of the four major spring groups on a microscopic level.Furthermore,based on the analysis of spring water temperature frequency and water chemical characteristics,the results show that Baotu Spring and Heihu Spring are mainly recharged by karst water,and the shallow karst in the water replenishment area of Heihu Spring and Heihu Spring is relatively developed,and the precipitation replenishment is quickly obtained.On the basis of the karst water replenishment in the Pearl Spring and Tanxi Spring,they are also recharged by pore water and fissure water.(3)There are obvious differences in the runoff characteristics of the four major springs.Based on the correlation between precipitation and spring water level,frequency spectrum analysis,and spring flow attenuation analysis,the results show that:after concentrated precipitation,the response time lag of large fissure-pipe flow to precipitation is 7-16 days,and the proportion of conduit-fissure flow It is 0.84%?3.84%;the response time lag of fracture-pore flow to precipitation is 36?56 days,and the proportion of fracture-pore flow is 96.08%?99.17%;in addition,the fracture-pore flow is basically used in Tanxi Spring and Zhenzhu Spring.the Lord.(4)There are obvious differences in the discharge characteristics of the four spring groups.The discharge characteristics of different aquifers are studied by the EC frequency analysis of spring water.The method takes into account the mechanical mixing of groundwater in different aquifers and the hydrogeochemical action,which is more consistent with the actual hydrogeological conditions of spring water than previous researches on mechanical mixing of groundwater.The results show that the proportion of karst fissure water discharge in Baotu Spring is 31-54%in the middle Zhangxia Formation,and 45-68%in the Ordovician.In the Heihu Spring,karst fissure water in the Middle Zhangxia Formation accounts for 24?31%,and in the Ordovician fissure karst water accounts for 68?75%.The proportion of karst fissure water discharge is 60-70%in the middle Zhangxia Formation,15-17%in the Ordovician,8-21%in the source water discharge,and 6%in the pore water discharge and weathering fissure discharge.In Pearl Spring,60%of karst fissure water,22-25%of Ordovician fissure karst water,13%of supplemental water,5-6%of pore water and weathering fissure water are discharged from the middle Zhangxia Formation.(5)Based on the analysis of tritium isotopic data of spring water and groundwater,the age of the groundwater in the Zhangxia Formation aquifer in the spring area is 48-82 years,and the age of the shallow Ordovician groundwater in the spring area with a buried depth of 100m is less than 6 years.Groundwater quickly replenishes spring water;the deep Ordovician-Cambrian Fengshan Formation aquifer at a depth of 100m has a strong water storage function,and the flow rate of groundwater is slow,and the age of karst water is 6-55 years.A piston-mixed flow model suitable for Jinan originating from hydrogeological conditions was established,and the groundwater ages of Baotu Spring and Zhenzhu Spring Tanxiquan were measured to be 10,23,and 21 years,respectively.