A Study Of Groundwater Circulation On A Typical Profile In Qaidam Basin

The Qaidam Basin is located in the northwest of China,in Qinghai Province.Its climate is arid and semi arid,and the altitude is 2700-3500m.Because of the frequent tectonic activities during the geological history and various structures in different directions,the hydrogeological conditions is more complex.The study area is located in southeast of the Qaidam Basin,which has scarce rainfall,strong evaporation and fragile ecological environment,so that the dependence of the local residents living water and wolfberry industry to groundwater resources is very high?Therefore,finding out the occurrence regularity of groundwater in Qaidam basin,developing the groundwater resource and managing the groundwater resource reasonably are hanging over the local government's head.According to the project of "Conversation and renewability of groundwater and surface water in Qaidam Basin ",this paper identifies the source of groundwater in Nomhon by the way of hydrogen and oxygen stable isotope,then estimates the volume of transformation between the surface water and groundwater,as well as estimates the percentage of lixiviation and evaporation to TDS.It also estimates the percentage of groundwater in CK8 from the Xiangride and Nomhon directions and finds out the chemical evolution of groundwater,as well as identifies the causes of groundwater in different sections.It is difficult for atmospheric precipitation to recharge the groundwater in the alluvial fan area around the basin.This paper determines the mountainprecipitation as the main recharge sources of groundwater in the surrounding alluvial proluvial fan,which combines the evidence of the hydrogen and oxygen stable isotopes and the hydrochemical.Owing to the large coverage area of glacier in southern mountain region of Nomhon,the meltwater makes a great contribution to the Nomhon river.This paper takes measures of the hydrogen and oxygen stable isotope to estimate the recharging ratio of the Nomhon river from atmospheric precipitation and meltwate in mountains are 21.1%and 78.8%.According to the isotope mass balance and the principle of water balance,it aslo estimates that the recharge of Nomhon river from the groundwater is 0.071?0.098×108m3/a.In the center of the basin,the chemical type of groundwater is single and the degree of mineralization is great.At the drilling of CK8,the main source of the degree of mineralization are lixiviation and evaporation,and their contribution to TDS are 21.6%and 78.4%.There are two parts to recharge the groundwater at CK8,which come from Xiangride and Nomhon and the ratio of them is about 3.7:1.Combining the evolution of the basin,Quaternary tectonic movement and the hydrochemical analyse results,this paper analyses the chemical andcauses in different sections and hydrochemical evolution of groundwater.