Groundwater Chemistry And Its Evolution In The Middle Reaches Of Heihe Basin

The middle reaches of Heihe Basin is located in the northwest of China.The climate is arid and evaporation is large.Groundwater plays an important supporting role in the production and life of this region.Therefore,it is of great significance to develop the characteristics of groundwater chemical types,the genesis and mechanism of hydrochemical components,and the study of water quality for the rational utilization of groundwater resources in this region.Based on the middle reaches of heihe basin as the research object,this paper detailed the find out the geological and hydrogeological conditions in the study area,based on the Gibbs diagram,the Pipper three chart,ion ratio relationship,shu card Lev classification,isotope ratio,water quality evaluation of technical methods such as statistical characteristic of groundwater chemical composition in the study area,the spatial distribution characteristics,water chemical evolution,ion source component content such as study,and to evaluate the underground water quality,detailed analysis of water quality change.The main insights gained are as follows:?1?In the whole study area,SO₄^2-,HCO₃^-and Cl-ions were the main dominant ions in the groundwater chemical components,while Mg²⁺,Na⁺and Ca²⁺were the main dominant ions in the cations.Their spatial distribution characteristics showed obvious east and west differences.Along the direction of groundwater flow,the groundwater chemical types have undergone a process from HCO₃^-·SO₄^2-·HCO₃^-type,SO₄^2-type,SO₄^2-·Cl^-type to Cl^-type.It accords with the general law of the evolution of groundwater chemical types in northwest China.?2?Gibbs chart indicates that the dominant mechanism of groundwater chemical composition evolution in the study area is rock weathering,followed by evaporation.The mineral saturation index indicates that calcite,dolomite,salt and gypsum are dissolved in Beihe basin and Heihe Basin.The source of Ca²⁺,Mg²⁺and HCO₃^-ions in groundwater is often the dissolution of carbonate minerals,such as calcite and dolomite.The chlor-alkali index showed that there was cation exchange in heihe river basin and reverse ion exchange in Beida River basin.?3?the groundwater quality evaluation results,show that the groundwater in the study area is poorer,?water accounted for 29.4%,?accounted for 27.4%,?accounted for 43.1%,no?class water and water?type.There are two important reasons,one is the influence of hydrogeological conditions,the other is the influence of human activities.