Abstract:

The Shaliuhe River Basin is located in the territory of Gangcha County,Qinghai Province,China and in the northern part of Qinghai Lake.Located in the transition zone of westerlies and monsoons,the basin experiences significant seasonal variations in precipitation,with approximately 65% of precipitation concentrated during the monsoon period.There are relatively abundant groundwater resources in the Shaliuhe River Basin,mainly including bedrock fissure water in the northern mountainous region of the basin,phreatic water in gravel layers of piedmonts and intermontane plains,and confined water in the downstream lakeside plains.From July to November 2017,the author collected about 300 samples of shallow groundwater,spring water,glacier snowmelt water,and river water in the middle and lower reaches of Shaliuhe  River Basin.Spatio-temporal variation characteristics of hydrogen and oxygen stable isotope composition of shallow groundwater and the recharge relationship between groundwater and other water bodies in different periods were studied in Shaliuhe River basin of Qinghai Lake using GIS spatial interpolation method and stable isotope techniques.The conclusions were drawn as follows:(1) during the monsoon period,groundwater is mainly recharged by rainfall infiltration and lateral recharge of rivers,and evaporation is the main factor affecting the stable isotope value of groundwater.In the non-monsoon period,the glacier snowmelt water has a significant impact on groundwater in the low-value area,and the rapid infiltration of precipitation is one of the main recharge paths of groundwater in the highvalue area.(2) in the high-value area of groundwater isotope,the recharge between groundwater and river water is weak,and the recharge time is more than 5 months.In the low-value area of groundwater isotope,groundwater has a close supply relationship with river water,and the supply time is from January to April.At present,there are few studies on groundwater stable isotopes in China,especially in the Qinghai-Tibet Plateau where there is a lack of seasonal difference in groundwater recharge path.Therefore,the results of this study can preliminarily reflect the stable isotope characteristics of groundwater and the basic law of recharge pattern in the arid and semiarid inland basins to a certain extent.The results also provide a scientific basis for the study of conversion  between groundwater and other water bodies within the basin,and theoretical guidance for groundwater resource management and water environment treatment.

Key words: shallow groundwater, hydrogen-oxygen stable isotope, groundwater supply, Qinghai Lake, Shaliu River Basin