Evaluation of potential evapotranspiration in the Weihe River Basin based on statistical downscaling

Abstract

The Hargreaves method of using the average temperature (Tav) was used to calibrate the estimation of potential evapotranspiration (PE) for daily meteorological data of 35 weather stations from 1951 to 2015 in the Weihe River Basin and a statistical downscaling model was applied to downscale the Hadley Centre Sea-Atmosphere Coupled Model (HadCM3) output data to each station. The future temporal and spatial variations of temperature and evapotranspiration under different climate change scenarios were evaluated for the periods of 2016–2039, 2040–2069, and 2070–2099. The results show that the downscaling method is well suited for estimating the PE and that the PE in the Weihe River Basin is larger in May–July and smaller in autumn and winter. The mean annual temperature and annual PE exhibit an increasing trend for the high greenhouse gas emission scenario (RCP8.5) and low greenhouse gas emissions scenario (RCP4.5) and the magnitude of increase is greater for the RCP8.5 scenario. Greater increases in the PE were mainly distributed in the south of the Weihe River, the upper reaches of the Beiluo River, and the middle reaches of the Jinghe River, whereas most of the northern reaches of the Weihe River exhibited smaller changes that were located in the lower reaches of the Jing River. The regional distribution of the PE is consistent with the temperature changes. This study provides the basis for regional water resource management planning.