Study On Model Of Managed Aquifer Recharge Through Yufu Channel Infiltration Experiment In Jinan

Due to the continuous decline of the groundwater level in Jinan spring area,the water supply in the four springs group and the city of Jinan City is seriously threatened.In the southern mountainous area of Yufu River,the use of artificial control of the river water recharge method of groundwater is an important measure to increase the amount of groundwater.Although the upper reaches of the Yufu River is a strong leaking area,its terrain,stratigraphic structure and the downstream Ordovician aquifer is particularly related to the hydraulic connection,which seriously restricts the efficiency of river water recharge karst water.In this paper,the typical case of Yufu River is used to study the water diversion scheme and natural law of groundwater discharge in the off-type river,and it is found that the river is different from the natural river.Based on the methods of field investigation,surveying,monitoring,calculation and experimental verification,the two-dimensional vertical profile of groundwater along the river direction under different conditions and different water discharge conditions was analyzed.The conclusions are as follows:(1)Yufu River is a disconnected losing river that is controlled by artificial flooding,which has the characteristics of intermittent and water instability,and there is a representative multi-layer complex geological structure,and its upper layer aquifer permeability coefficient is large,The lower aquifer has a small permeability coefficient,and The lower section of the stratum contains impervious shale.Under this kind of geological structure,there are many factors influencing the recharge efficiency,water flow rate and flux,cycle time,groundwater depth,gas zone thickness and so on.(2)According to the calculation reasoning and experimental verification,it is shown that the process of surface river water recharge and transportation to the groundwater can be divided into multiple stages.The duration and timing of each stage vary according to the groundwater depth and surface water velocity,But its overall law is similar.(3)Recharge cycle.According to the calculation,it is concluded that the recharge cycle depends on the surface water velocity(ie,the flux of recharge)and the groundwater level,and the influence of the surface water velocity is much greater than that of the groundwater level.(4)Recharge efficiency and daily recharge flux during the recharge cycle.According to the recharge plan,the recharge water can be used efficiently,and the efficiency is above 95%.Because there is a non-recharge period in a water discharge cycle,the actual recharge rate is smaller than the controlled outlet flux of the gate.However,after the calculation,theguarantee rate in the recharge scheme is higher(over 92.5%)and the effect on the recharge is little.