Temporal and Spatial Characteristics of Actual Evapotranspiration in Jinghe Watershed, Xinjiang

The Jinghe watershed is an important part of the North Slope Economic Development Belt of the Tianshan Mountains in Xinjiang. The meteorological data of the period from 1953 to 2015 and the Landsat 5 TM images of the years 1998, 2007 and 2011 of the region were analyzed for spatio-temporal variation of the actual evapotranspiration, its characteristics and periodicity with the help of the Penman-Monteith formula, SEBAL model, Morlet wavelet analysis model and M-K mutation test model. Results show:(1) Temporal and spatial distribution of evapotranspiration is influenced by meteorological factors and underlying surface in the Jinghe watershed. The evapotranspiration of the past 60 years as a whole exhibits a significant declining trend with fluctuation in the year 1967 and 1994. In terms of temporal evapotranspiration variation rate, the four seasons follows an order of summer > spring > fall > winter. (2) The mean annual evapotranspiration dropped about 150.654 mm (17.361%) after the sudden change in 1982. The variation of the actual evapotranspiration consisted of three oscillation periods, each lasted for around 29 years, which indicates that in the 15 years to follow the mean annual evapotranspiration tends to ascend first by a small margin and then descend. And (3) spatial distribution of the evapotranspiration is significantly related to the type of land use, and it declines with the type of surface land use follows an order of waters>cultivated land>forest land>grass land>unused land.