Study On Infiltration Promotion Techniques During Artificial Recharge Of Groundwater

Large-scale development and utilization of groundwater resources in North China Plain has caused a series of environmental and geological problems.Large-scale landfall funnels are formed due to overexploitation of groundwater in many areas,and artificial recharge and storage of groundwater are urgently needed.In 2019,the"?Action Plan for Comprehensive Treatment of Groundwater Overdraft in North China?"jointly issued by the Ministry of Water Resources,the Ministry of Finance,the National Development and Reform Commission and the Ministry of Agriculture and Rural Affairs proposed that first,pilot projects should be carried out in areas with serious groundwater overexploitation in Hebei Province.Combined with water source conditions and river and lake governance,other river and lake ecological water replenishment and groundwater recharge should be gradually promoted.However,in the North China Plain,the artificial recharge conditions of groundwater in many areas are not ideal.Therefore,how to improve the infiltration efficiency of groundwater artificial recharge project has become one of the key technical problems affecting the comprehensive management of groundwater overexploitation areas,which has important practical significance.This study relies on the national key research and development plan project"groundwater artificial recharge and storage in Xiongan New Area(2018YFC0406503)".Through field investigation and combined with the collected data of the study area,the feasibility and suitability of groundwater artificial recharge in the study area are analyzed in view of the problems of groundwater overexploitation,water diversion source surplus and low utilization rate in the study area.On the selected typical areas,systematic research is carried out on the key problem of"how to quickly and safely infiltrate surface water sources into underground aquifers".The main research results are as follows:(1)Taking the recharge water source,lithology of aeration zone and groundwater table depth as the main indexes,the weight was calculated according to the analytic hierarchy process(AHP),and then the superposition calculation was carried out.The artificial recharge suitability of groundwater in the study area was divided into four grades:strong suitability,strong suitability,medium suitability and unsuitable suitability.In full consideration of the water quality and water quantity of recharge water source,the location of landing funnels in Xiong County and Rongcheng County,the Baigou River Diversion Bank was selected as the typical area of this study.(2)The influencing factors of surface water infiltration capacity in typical study area under natural conditions were analyzed from the aspects of particle size distribution characteristics,particle size characteristics and spatial distribution characteristics of infiltration medium,and the main limiting conditions of groundwater artificial recharge efficiency were determined.(3)Based on the different artificial recharge methods of groundwater,the surface infiltration recharge infiltration promotion technology and recharge well infiltration promotion technology are proposed respectively.The indoor simulation experiments show that compared with natural infiltration conditions,the system permeability coefficient has increased by 67%when the surface infiltration recharge infiltration promotion technology is applied,and the system permeability coefficient has increased by 49%and 70%when the recharge well enters the depth of 10cm and 15cm of the sand layer.The indoor simulation experiment of infiltration promotion technology has guiding significance for the development of field demonstration projects.(4)On the basis of laboratory experiments,comsol was used to simulate and analyze the change of infiltration rate in the process of artificial recharge of groundwater.It is proved that the established model can effectively predict the development process of clogging in the artificial recharge system of groundwater,and can be used to predict and control the infiltration efficiency of actual groundwater artificial recharge projects.(5)After the application of two seepage promotion technologies in the typical area for regulation and storage,the artificial recharge amount of groundwater can reach about 8.94×10~6 m~3 per year through theoretical calculation,and the total amount of groundwater recharge can be increased by 3.5 times.