Changing characteristics and attribution analysis of potential evapotranspiration in the Huang–Huai–Hai River Basin, China

Evapotranspiration is a key component of the hydrological cycle. It is important to understand the features of the variation of potential evapotranspiration and the impacts of its drivers to estimate regional water consumption. The Huang–Huai–Hai (HHH) River Basin is comprised of three major rivers (the Yellow, Huai and Hai) and has been threatened by water shortages and huge consumption of water for agricultural and industrial development. In this study of the Huang–Huai–Hai (HHH) River Basin, potential evapotranspiration (E0) across the basin was calculated using the Penman–Monteith model, and their changing characteristics were detected by using the Mann–Kendall test. The test was based on the daily climatic variables from 1965 to 2014 at 175 meteorological gauges. In addition, the influential effect of net radiation (Rn), relative humidity (RHU), wind speed (WIN), mean, maximum and minimum air temperature (Ta, Tmax and Tmin) on E0 were analyzed by using the climate elasticity method, with their relative contribution to the changes of E0 quantitatively revealed by using the multiple linear regression method. The results showed that Rn, WIN, RHU and Ta are the predominant climatic predictors that are more influential to E0 while Tmax and Tmin have the least impact. The increase in annual E0 in the period of 1985–2014 in the HHH River Basin was mainly attributed to the significantly increasing Ta, which may greatly offset the effect of decreasing WIN and Rn. The decrease of annual E0 in the period of 1965–2014 in the middle area of the basin was mainly attributed to the falling WIN and Rn.