Precipitation And Runoff Process In Shaliu River Basin Of Qinghai Lake Based On Hydrogen-Oxygen Stable Isotope Technique

The lack of water resources and the uneven distribution of water in the context of climate change have become one of the problems that constrain the stable development of mankind,and the water resources problem is still severe in the present and even in the coming decades.Rainfall and runoff are the main inputs and outputs of water in the basin,which play a crucial role in the conversion and balance of regional water.The Shaliu river basin is located in an important climate intersection zone,Qinghai lake ecological barrier zone,complex climate conditions,sparse hydrological and meteorological stations,and less research on water cycle processes in the basin.Therefore,this paper studies the precipitation and runoff sources and processes in the Shaliu River Basin by using hydrogen and oxygen stable isotope techniques as the main means,combined with GIS and meteorological methods.The main results are as follows:?1?The equation of the atmospheric precipitation line in the Shaliu river basin of Qinghai lake is:?D=8.3?¹⁸O+24.4.It is significant that the time-space difference of hydrogen and oxygen stable isotope values in precipitation.The time is characterized by summer half-year enrichment,winter half-year depletion,and spatially low upstream and downstream.The continental effect,lake effect and temperature effect of?¹⁸O value are more significant in the basin.The environmental effects vary greatly with the seasons,and the performance is higher than the summer half year in the winter half year,and the relevant changes are also the same.?2?The characteristics of the stable isotopic composition of precipitation hydrogen and oxygen are similar to those in northwestern China.The atmospheric precipitation is mainly affected by westerly circulation,east asian monsoon and polar cold current;The seasonal variation of precipitation water vapor source is more significant.In summer?June-August?,it is mainly the southeast monsoon,westerly circulation and inland recirculating water vapor;In winter?12² months?,the westerly circulation dominates and there is the influence of polar air mass;The westerly circulation,the southeast monsoon,the polar water vapor and the recycled water vapor all contribute to it.?3?Runoff isotopic composition(?D and?¹⁸O)and d-excess of the Shaliu river basin are more moderate than rainfall,and the fluctuation trend has a certain similarity with the rainfall.The spatial variation of?¹⁸O value of the Shaliu River dry tributary is the characteristics of south high and low north.There is obvious altitude effect:the whole year,summer half year and winter half year are respectively-0.33‰/100 m?p<0.01??-0.22‰/100 m?p<0.01?and-0.5‰/100 m?p<0.01?.?4?There are obvious spatial and temporal differences in runoff recharge characteristics in the Shaliu river basin.In the summer half year,atmospheric precipitation and groundwater are the main sources of runoff;in the winter half year,groundwater and runoff complement each other;in winter and summer,the precipitation is replenished with snow and ice and groundwater.From the low-altitude alpine steppe belt,the ratio of atmospheric precipitation to runoff is gradually increased during the transition from alpine meadow belt to high-altitude alpine desert belt?25.1%?36.7%?40.0%?.The more precipitation has a runoff recharge relationship.It is obvious about groundwater is still the main source of runoff in the Shaliu River Basin,and the recharge ratio is greater than 60%.