The Influence Of Multistage Flow System In Jinan Spring Region On Spring Dynamics

The karst groundwater system in Jinan spring area has strong water abundance,and its abundant groundwater resources provide guarantee for social development.However,the spring water is still threatened by interruption or short-term interruption in dry seasons over the years.The fundamental reason is that there is a lack of clear understanding of the karst water system in Jinan spring area.Therefore,this article mainly focuses on the karst water system in Jinan spring area as the research object.Based on the investigation of the hydrogeological conditions in Jinan spring area,through monitoring the water level and quality of spring and groundwater,tracing experiments,tritium isotope testing,and numerical simulation of groundwater,classification elements are identified from three aspects:groundwater hydrodynamic field,hydrochemical field,and temperature field characteristics,and different levels of flow systems are divided,Reveal the impact mechanism of different levels of flow systems on spring water level,quality,and quantity.The main conclusions are as follows:（1）Based on the characteristics of the hydrodynamic field,hydrochemical field,and temperature field in the Jinan spring domain,combined with the numerical model of groundwater,it was found that there are different levels of flow systems in the Jinan spring domain that recharge the spring water.Among them,the indirect recharge area is the Cambrian Zhangxia Formation aquifer with a relatively high distribution elevation.After receiving the recharge from atmospheric precipitation,it migrates deep underground under gravity and supplies the Cambrian Fengshan Formation Ordovician aquifer and spring water through faults,Participate in the regional flow system to replenish the spring cluster.After receiving atmospheric precipitation recharge,the Cambrian Fengshan Formation aquifer and the Ordovician aquifer in the direct recharge area form an intermediate flow system to recharge the spring group.There are local flow systems in both the direct recharge area and the runoff discharge area of the spring domain.In the direct recharge area,the karst water of the Ordovician Majiagou Formation participates in the local flow system to form an artesian spring.In the runoff discharge area,the karst water of the Ordovician Yeli Formation and Liangjiashan Formation participates in the local flow system to recharge the spring water,thus dividing different levels of flow systems.（2）Using MODPATH for streamline tracking,it was determined that the karst water of the Yeli and Liangjiashan formations participated in the local flow system to supply the four major spring groups.The karst water of the Fengshan formation participated in the intermediate flow system to supply the four major spring groups.The karst water of the Zhangxia formation participated in the regional flow system to supply the four major spring groups.The Qianfoshan fault has control significance for the formation of the four major spring groups in the Jinan spring domain.（3）Different levels of flow systems have different impacts on the hydrochemical types of spring water.The influence of Wangfuchi on the regional flow system has shifted from HCO₃·SO₄·Cl-Ca·Mg to HCO₃-Ca.The influence of Tanxi Spring on the middle flow system has a relatively stable hydrochemical type,while Heihu Spring is mainly influenced by the middle flow system,and the local flow system also has an impact on Heihu Spring,Baotu Spring was mainly influenced by the local flow system along the Jingshi Road from 2016 to 2017,with a hydrochemical type of HCO₃·SO₄·Cl-Ca.After 2017,the hydrochemical type changed to HCO₃·SO₄-Ca due to the influence of the intermediate flow system.（4）By using a multiple linear mixed model,the contribution ratios of different levels of flow systems in Jinan spring area to spring flow were obtained.Among them,the contribution ratios of local flow systems in Baotu Spring Group,Heihu Spring Group,Wulongtan Spring Group,and Zhuzhu Spring Group were 56%,40%,43%,and 40%,respectively;The contribution ratios of the intermediate flow system are31%,49%,29%,and 31%,respectively;The contribution ratios of regional mobility systems are 13%,11%,28%,and 29%,respectively.Through autocorrelation and spectral analysis,cross correlation and cross spectral density function analysis,gain function and phase function,the response time of spring water level to groundwater in local flow system is about 7～21 days,and the response time to regional flow system is about 36～56 days.（5）According to the cross correlation function and discrete Fourier transform algorithm,the dynamic effects of different levels of flow system systems in the southern spring region on spring water conductivity are calculated.Among them,the response times of Baotu Spring,Heihu Spring,Tanxi Spring,and Wangfu Chizi to the local flow system are 16 days,18 days,14 days,and 17 days,respectively;The response time for the intermediate flow system is 21 days,20 days,23 days,and 22days,respectively;The response times for regional flow systems are 32 days,34 days,35 days,and 38 days,respectively.