Soil evaporation and its hydrological effects in subalpine shrub zone of the eastern Qilian Mountains in China

Soil evaporation is an important part of regional ecohydrological process. The study about soil evaporation based on the technique of stable isotopes has become an important content of regional water cycle process. In this study, using precipitation and soil water samples collected in the subalpine shrub zone of the Qilian Mountains from May to October 2019, soil evaporation at different soil depths and soil evaporation loss f were calculated by the lc-excess and Craig-Gordon models, and their influencing factors and hydrological effect of evapotranspiration variations were analyzed. The results showed that soil evaporation loss f in the early (May-June), middle (July-August) and later (September-October) of the growing season were 38.70%, 45.03%, 21.34% and 40.60%, 43.36%, 22.26% for semi-sunny and semi-shaded aspects, respectively, and both of them showed a tendency to increase firstly and then decrease. The lc-excess values of soil evaporation on two aspects were middle of growing season > early of growing season > late of growing season, and the intensity of soil evaporation was weaker on the later than the former as a whole. Soil evaporation loss f on both aspects was positively correlated with temperature (T), wind speed (W) and solar radiation (SRA), and negatively correlated with precipitation (P), relative humidity (RH) and soil water content (SWC), with the correlation from strong to weak as T>P>W>RH>SRA>SWC.