Characteristics of near-surface soil-vegetation-water body evapotranspiration and water vapor isotope in typical days in source region of the Yellow River
Based on the in situ observation of evaporation and water vapour isotope,the study investigated the characteristics of near-surface soil-water-vegetation evaporation and transpiration in Wangjiaxiang,a typical area in source region of the Yellow River,and explored the isotopic features of water vapour emitted from soil,vegeta-tion,and water bodies.The study also calculated the proportion of evaporation and migrating water vapour.The results show that the peak time of soil and vegetation evaporation is delayed relative to the peak time of water body evaporation,and the influence of evaporation on soil water depth is 20 cm.There are significant differences in the isotopic values of evaporation between different observation objects(bare soil,vegetation,water bodies,and mixed),the isotope fractionation process during plant transpiration is generally stronger than that during soil evaporation.The isotopic fractionation effect becomes stronger as the depth of soil water consumed by evapora-tion increases.Evaporation causes the observed water vapour δ18O,δD and δ17O to initially enrich and then stabi-lize,indicating the existence of an isotopic equilibrium process,while the d-excess continues to decrease during evaporation.The hourly Rayleigh fractionation model can reflect the changes in the isotopic composition of evap-oration water vapour to a good extent.The results of the endmember mixing model for water vapour isotopes show that the near-surface observation site,water vapour is mainly dominated by evapotranspirationn.Future wa-ter resource allocation and management should pay more attention to the impact of climate change on soil evapo-ration.
soil evapotranspirationwater vapour isotopesRayleigh fractionation modelsource region of the Yellow River
万方数据
维普
