Simulation Study On The Evolution Rule And Mechanism Of Groudwater's Chemical Composition In Gudui Spring

The Gudui spring area is located in the southern part of Shanxi Province.There is little rainfall and strong evaporation in this area.The shortage of surface water resources and relatively abundant groundwater resources in the spring area make groundwater resources the main source of water in this area.Therefore,it is of great practical significance to study the source and spatial distribution characteristics of the main hydrochemical components,the law of hydrochemical evolution,and the mechanism of multi component water chemical action in the area.Based on the analysis of the characteristics of the chemical composition of the groundwater,the spatial distribution of the main components and the distribution of the hydrochemical types in the study area,the hydrogeochemical evolution and formation mechanism of the groundwater are quantitatively studied by using the hydrogeochemical simulation method.It also predicted the possible influence of different proportions of reservoir water and underground water on the composition of groundwater under the influence of reservoir leakage.The main results are as follows:?1?The research area is located in the south of the Linfen basin.The whole direction of groundwater discharge is from northeast to southwest,and Gudui spring is the lowest discharge point in the study area.The dynamic of groundwater level has the characteristics of Meteorology and exploitation.The groundwater level in the study area is generally in a downward trend.?2?The chemical type of groundwater is complex.Karst water is mainly composed of SO₄ ^2-and HCO₃^-water,while pore water is dominated by HCO₃^-·SO₄ ^2-type water,and the chemical type of water is complex.The spatial distribution of main components of pore water and karst water,except Na⁺+K⁺and Cl^-,is similar,all of which show that the distribution of total hardness,SO₄ ^2-,F^-and Fe are obviously different from the increase of the supply area to the discharge area.?3?The results of mass balance simulation show that gypsum,dolomite,Halite,fluorite dissolve,calcite precipitation,and Ca-Na cation exchange in the recharge area of the study area are mainly taken place.From the supply area to the runoff area,halite,dolomite,gypsum,fluorite dissolution,calcite precipitation and Ca-Na cation exchange occurred.From the runoff area to the final discharge area,the dissolution of gypsum and halite,the precipitation of dolomite and fluorite,and the cation exchange between Na⁺,Ca²⁺and Mg²⁺have been experienced.?4?The simulation results showed that the content of Cl^-,Na⁺,Mg²⁺and Fe increased with the increase of the proportion of reservoir water in the mixing process of water and groundwater 0.5:0.5,0.4:0.6,0.3:0.7,0.2:0.8 and 0.1:0.9,and the content of HCO₃^-,SO₄ ^2-,F^-,and Ca²⁺components decreased with the increase of the proportion of reservoir water.The saturation exponent of calcite and dolomite increases with the increase of the ratio of reservoir water to saturated state.The saturation index of fluorite and gypsum decreases with increasing proportion of reservoir water and develops towards dissolved state.?5?The results of forward path simulation show that the content of each component of groundwater changes along the flow path under the constraints of the results of the different proportion of water and groundwater and the mineral phase saturation index considering the continuous seepage effect of the three spring reservoir.The increase of Mg²⁺and HCO₃^-content along the flow path increased to 15%,while the content of SO₄ ^2-,Na⁺,Ca²⁺,Cl^-and F^-decreased relatively,the most obvious was SO₄ ^2-,between 78%and 81%,and the content of Mg²⁺and HCO₃^-increased with the decrease of the ratio of reservoir water,and the content of the other ions decreased with the decrease of the ratio of reservoir water.