Numerical Simulation Research On Groundwater Environment Evolution Of Gudui Spring Ecological Restoration

Guidui spring is one of the famous karst spring in Shanxi province having a flow rate of 1.3m~3/s,it cut off at 1999,and the depth of spring water level was63.3m in 2016.There are two main measures of Guidui spring ecological restoration according to research:One is the Sanquan reservoir leakage,and another one is well-shut &limiting exploitation.Firstly,the paper takes a comprehensive analysis of the investigation while Sanquan reservoir impoundment?geological survey data?environmental isotope determination and reservoir hydrological monitoring information,and a study on the model intensity and Sanquan reservoir leakage.Then according to reservoir operation characteristics and shut-in &limiting exploitation,numerical simulation is carried out to study the evolution of groundwater level and main pollution factors in Guidui spring under different working conditions.This paper will provide technical supports for the Guidui spring ecological restoration.The results show that:(1)The reservoir leakage area can be divided into karst filling type area with strong permeability?pore-karst dual medium area with slow infiltration and pore water runoff recharge area;(2)the model of leakage intensity at the present condition is Sp = 4.7(H-440)+4;(3)The impact area of Sanquan reservoir leakage on groundwater level is about 26.6km~2 ?30.6km~2;(4)The water level near the spring vent experienced a short period of rapid recovery(0-1.3a),rise speed is 16.06m/a-24.09m/a.And then is the undulate rise stage.The third stage is equal amplitude recovery with a rate less-than 1 m/a until the springs flow again;(5)Under the conditions of that the amount of precipitation is long-time average annual value and normal reservoir storage and the second phase well-shut &limiting exploitation.The karst water near the spring vent need 35 years to restor from 379.7m to 443.0m;(6)The influence extent of fluoride on pore water is about 46km~2,there are two pollution halo on east sides of Jiuyuan mountain.Its maximum pollution halo peak are 4.6mg/L?3.2mg/L,added increase of 3 and 1.54 times;the influence area of fluoride on karst water is about 1.2km~2 near tail of water reservoir.The maximum concentration of pollution halo is 2.26mg/L(2019/10),and then decreases to standard after 33a;The influence of sulfate on groundwater quality is only around the reservoir.The maximum of pore water pollution halo is 450.4mg/L,1445 m from the edge of the leaking zone,and will decrease since then;While the maximum of karst water pollution halo is 507mg/L,2285 m from the edge of the leaking zone.Then the pollution halo will move along the water direction to karst water depression at the north of the reservoir leakage area.