Isotopic And Water Vapor Source Analaysis Of Diffe Rent Water Area Of Kashi River Basin

Water is an important material,all things can not grow without water,the development of human civilization also needs water.Water is indispensable to both nature and human society.Although the total amount of water resources on the earth is large,but the distribution is uneven.Northwest China is one of the regions in the world where water resources are very scarce.In recent years,due to the development of economy and society,the demand for water resources is more and more vigorous.In China,with the development of the western region,the pressure of water shortage in the northwest arid area is increasing.Kashi River is the second largest tributary of the Yili River,located in the west of Tianshan Mountains.It is relatively rich in precipitation in Xinjiang.The study of environmental isotopes in precipitation and river water in this place can provide important scientific support for the study of the process and mechanism of the generation,development and change of river water resources in Northwest China,and has important practical significance for the protection of the environment and the utilization of water resources significance.Based on 186 samples of atmospheric precipitation,river water,ice and snow melt water collected in Kashgar basin from January to December 2018,the stable isotope characteristics,spatiotemporal variation and environmental significance of precipitation and river water were studied,and the sources of precipitation and water vapor and the composition of runoff recharge were traced.The main conclusions are as follows（1）Stable isotope characteristics of hydrogen and oxygen in precipitationThe hydrogen and oxygen isotopic values of precipitation in Kashi River Basin fluctuate significantly.The isotopic values of hydrogen and oxygen are higher in summer and lower in winter.Stable isotopes of precipitation in the basin show significant temperature effect.The temperature is high in summer,δ¹⁸O enrichment;the temperature is low in winter,δ¹⁸O low.The change ofδ¹⁸O value in precipitationis mainly proportional to the temperature.he precipitation effect of stable isotopes in the basin is not reflected in the whole year,but there is a certain precipitation effect in autumn.The slope and intercept of the local meteoric water line in the study area are small in summer half year,and the slope and intercept of the local meteoric water line in the study area are small in winter half year.This is because the temperature is low in winter,the precipitation is little affected by the secondary evaporation under the cloud,even negligible,while the temperature is high in summer,the effect of secondary evaporation under the cloud on the precipitation isotope can not be ignored.（2）Stable isotope characteristics of hydrogen and oxygen in river waterCompared with atmospheric precipitation,the stable isotope of river water has no obvious change in the year,and the difference between the highest and lowest values is small,which is relatively stable on the wholel.The seasonal variation is not obvious,and it is slightly higher in summer than in winter.On the spatial scale,the stability of river water shows altitude effect,that is,with the decrease of altitude,the evaporation fractionation increases,and the stable isotopes of hydrogen and oxygen in river water gradually enrich.The results show that the temperature in the study area is low,the secondary evaporation under cloud is weak,the deuterium surplus of atmospheric precipitation is larger than the average deuterium surplus of global precipitation,and the slope and intercept of precipitation line equation are higher than the global atmospheric precipitation line.Due to the effect of evaporation fractionation,the slope and intercept of the river evaporation line are smaller than the local meteoric water lines.（3）Water vapor source analysis of precipitation and river waterBy using isotope and backward trajectory model,the results show that the water vapor in the basin mainly comes from the Atlantic Ocean and is transported to thelocal area through the westerly belt.In addition,the local recycled water vapor and Arctic water vapor are also important sources of water vapor.The sources of water vapor are different in different seasons.In summer,the total amount of water vapor is large,mainly from the North Atlantic and transported by the westerly belt.In addition,in summer,the temperature is high,evaporation is strong,and it will be supplied by local water vapor from Xinjiang and Central Asia.In winter,it is mainly affected by the Arctic air mass,and precipitation is scarce.In July and August,the main source of river water supply in Kashi River Basin is precipitation in mountainous area,followed by ice and snow melt water,and spring water supply is the weakest.