Analysis Of Surface Water And Groundwater Chemistry Characteristics In The Sponge City Construction Area

Water resources have been the focus of attention all over the world.The construction of sponge cities is one of the effective measures to systematically solve the shortage and deterioration of water resources.However,in the process of sponge cityconstruction,part of the polluted surface water which is hydraulically connected with groundwater,posing the risk of potential contamination to groundwater.In this paper,the typical crosections of the Beiyun River are taken as the research objective toexplore the current conversion relationship and its impact process between surface water and groundwater,providing scientific support for future sponge cityconstruction,pollution monitoring and early warning.Three typical crosections are selected based on data collection of research area.Through the analysis of hydrochemical characteristics,combining withhydrogeological condition,several conclusions can be drawn as following:?1?The lithology of the shallow strata of the three typical sections is mainlycomposed of sand,coarse sand and fine sand,the groundwater sample of Tugouprofile and Yangdi profile are taken from semi-confined aquifer and Hehe's fromunconfined aquifer.Surface water body recharges the aquifer.?2?The sources of surface water are treated wastewater,precipitation and backwaterof irrigation,whose hydrochemical types are mainly HCO₃-Na·Ca and HCO₃·Cl-Na·Ca.?3?The major anion and cation of the three profiles are HCO₃^-,Ca²⁺and Na⁺respectively.The variance of main water-quality indicators are regular in spaceand time.The value of concentration of Ca²⁺,SO₄^2-,HCO₃^-,Cl^-and pH,as well asTDS is sorted as:Tugou profile<Yangdi profile<Hehe profile,which is risingalong the direction of groundwater flow?form northwest to southeast?.?4?In the three typical profiles,as the distance away from the river decreases,theproportions of HCO₃^-and Cl^-are increasing and decreasing respectively.Aconservative ion with better mobility Cl^-is selected to determine the influencerange of groundwater recharge by river water in different profiles according to theconcentration data collected from monitoring points in the profiles:the influencedistance of Tugou profile is 92 meters,Yangdi profile is 31 meters,and Heheprofile is 165 meters.?5?Results from the Gibbs diagram,analysis of ion proportion and the influence ofsurface water on groundwater demonstrate that the groundwaterhydrogeochemical ingredient is mainly influenced water-rock interaction andinfiltration of surface water.