Identification Of The Dominant Seepage Channel In Jinan Karst Springs

The type of aquifer medium,the development degree of karst fissures and the karst spring landscape in the karst water system of Jinan are typical representatives of karst in northern China.This paper is based on the direct recharge area of Jinan Spring Area.Based on the analysis of geological and hydrogeological conditions in Jinan area,Field geology survey,groundwater level dynamic monitoring,field drilling,tracer test,fuzzy comprehensive discrimination and other methods are used to study from two aspects:water chemical field and hydrodynamic field.In this paper,the dominant channel of Jinan spring area is preliminarily determined,and three heat transfer models adapted to the study area are determined.Two dominant seepage channel identification systems are proposed,and a qualitative identification model of the dominant seepage channel of karst aquifer system is established for Baotu Spring to guide the work of protection of spring,and some protection measures are put forward.There is a certain theoretical and practical significance in this research.This article through the above analysis and research,draw the following conclusions:?1?The spring water level in Jinan Spring is closely related to atmospheric precipitation.The relationship between spring water level and rainfall is discussed under the tenth,five and three scales.The rainfall stations with shorter water level lag time and greater influence on spring water level at different time scales are Xinglong,Yanzishan and Donghongmiao.Among the three time scales,the correlation coefficient is the best under the sub-rainfall scale,and the relationship between the rainfall station and the spring group in the Ordovician area is relatively close,and the correlation coefficient is above 0.9,indicating that there is an advantageous seepage channel between the Ordovician area and the spring group.?2?According to the results of the two tracer test results,the duration curve of molybdenum ion concentration can be divided into single-peak and multi-peak curves,indicating that the karst water runoff channel in the spring field coexists with single-pipe type and multi-pipe type;According to the Xinglong Tracing Test,The Fengshan Formation aquifer in the Xinglong Leakage Zone does not have the dominant seepage channel for rapidly replenishing the spring group;A comprehensive analysis of the Xingji River tracer test and the Jingshi road tracer test shows that the Ordovician Majiagou Formation limestone aquifer has the dominant seepage channel of the recharged spring group,And the superior seepage channel identification system of“layer?well?horizontal extension direction”is summarized.?3?Affected by the regional groundwater flow,the vertical temperature profile of the study area consists of four types,a gradual cooling type,a gradual heating type,a temperature-increasing type and“S”type.Based on these four geothermal types,three heat transfer models adapted to the region were developed.The inflection point method is used to discriminate the horizontal runoff channels of the three depth segments in the Ordovician strata in the recharge area,and the shallow groundwater horizontal runoff intensity is greater than the deep.The temperature-tracking method is used to summarize the dominant seepage channel identification system of“layer?well?vertical occurrence depth”.According to the calculation of the thermal transport model,the Ordovician limestone in the direct recharge area of the spring area is shallow?at a depth of 100m?,and the vertical flow velocity of the groundwater is around 1.3×10^-7—3×10^-6cm/s,and the flow rate is slow.Based on the field tracer test,the visual flow of the karst water system was found to range between 29.41 and115.02 m/d,indicating that the karst water is dominated by horizontal motion.Since the method of temperature measurement in the hole is relatively simple,and the temperature change signal could be used to reveal the seepage characteristics of the groundwater.Overall,the application of groundwater tracer technology here confirmed that the karst development and seepage characteristics of Jinan spring area have heterogeneous characteristics.?4?The qualitative identification model of the dominant seepage channel in karst aquifer system is established by fuzzy discriminant method.On the basis of comprehensive consideration of the characteristics of the dominant seepage channel in the karst aquifer system,it is divided into four cases:karst fissure undeveloped,normal seepage channel,weak dominant seepage channel and dominant seepage channel.The fuzzy comprehensive discriminant method is used to identify the dominant seepage channel in the direct recharge area of Jinan Spring,and it is identified that there is a normal seepage channel in the recharge area,and there is an advantageous seepage channel in the runoff area.The feasibility of the fuzzy comprehensive evaluation model to identify the dominant seepage channel is verified by the tracer test and the correlation between the spring water level and atmospheric precipitation.It is proved that it is correct and reasonable to use the fuzzy comprehensive evaluation model to identify the dominant seepage channel of the karst water system.