Spatiotemporal Variation of Evapotranspiration in the Manas River Basin in Xinjiang

Abstract

【Background and objective】 Evapotranspiration (ET) is an important component in the hydrological cycle and is affected by many biotic and abiotic factors. Understanding its spatiotemporal variation in a region is hence central to help improve its water management. The objective of this paper is to analyse the spatiotemporal variation of ET across the Manas River Basin in Xinjiang of China. 【Method】 The analysis was based on data measured between 2000 and 2018. ET were obtained from the 500 m MOD16 ET product and the meteorological data measured from the basin; we considered five spatial resolutions and the time scale in the analysis was seasonal. From spatiotemporal distribution of ET in the region, we calculated its response to land use types, temperature and precipitation, using the means of mosaic, resample, grid calculation, linear regression and trend analyses. 【Result】 The annual average ET in the basin varied from 16.08 to 598.77 mm/a. Seasonally, the average ET in spring, summer, autumn and winter was 55.29 mm, 102.02 mm, 50.98 mm and 28.45 mm, respectively. The impact of land usage on ET can be ranked in the order of woodland> water body> cultivated land> spare land> construction land> grassland. For all land use types, ET peaked in summer, followed by spring, with winter being the least. The spatiotemporal variations in both ET and precipitation followed the same trend, and the correlation coefficient between them was 0.67. There was a weak but positive correlation between ET and air temperature. 【Conclusion】 Spatial variation of ET across the Manas River basin was significant. Temporally, ET was the greatest in summer and the least in winter; spatially, ET was high in the middle, and low in the south and north of the region. Along the river, ET was high in the middle reaches and low in the upper reaches.

Keywords

• evapotranspiration
• mod16
• spatial and temporal pattern
• manas river basin