Separating the contributions of climate change and human activities to regional AET variability by using a developed ana
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ORIGINAL PAPER
Separating the contributions of climate change and human activities to regional AET variability by using a developed analytical framework Lei Wu1 • Liuming Wang2 • Changbin Li1 • Yuan Zhang1 • Jianmei Wei1 • Xuhong Xie1 • Jianan Lv1 Accepted: 5 September 2020 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Actual evapotranspiration (AET) is a key factor in land-atmosphere interactions and a major hydrological cycle component. Variations in AET have resulted from a combination of climate change (CC) and human activities (HA). Quantifying the contributions of these two factors to AET dynamics is essential for better understanding hydrometeorological and ecohydrological processes under both natural and anthropogenic conditions. In this study, an analytical framework was adopted for AET variance analysis, and the influences of CC and HA on regional AET variabilities were separated by using this method. AET variance is determined by the variance in CC (r2AETc ) and HA (r2AETh ); the former is estimated through a synthesis of the variance/covariance of potential evapotranspiration (ET0) and precipitation (P), and the latter is determined from the residual between the total AET variance and r2AETc . Based on a 36-year dataset (1980–2015), this framework is applied to the different regions of the Tao River Basin (TRB). The results reveal that climate was the primary factor influencing AET variance in most parts of the basin. Precipitation (P) dominated the r2AETc and had a positive effect, while the interactions between P and ET0 tended to suppress this effect, especially in the semihumid areas of the TRB. The contribution rates of CC and HA to basin AET variance were estimated to be 0.76 and 0.24, respectively. The developed analytical framework and its application are beneficial to the management and exploitation of water resources from the perspective of basin ecohydrology. Keywords AET variability Separate Budyko equation Climate change Human activities
1 Introduction Actual evapotranspiration (AET) is the emission of water from the earth’s surface into the atmosphere in the form of water vapor (Yebra et al. 2013; Yao et al. 2017) and consists of evaporation from water body, soil and vegetative canopy systems or transpiration (Penman 1948). Research on basin AET is the basis of the quantitative analysis of water resources (Pandeya and Mulligan 2013), guidance of agricultural irrigation (He et al. 2019) and evaluation of regional drought (Wang et al. 2019a, b). In & Changbin Li [email protected] 1
MOE Key Laboratory of Western China’s Environmental Systems, College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, China
2
School of Geography and Ocean Science, Nanjing University, Nanjing 210000, China
the context of climate change (CC), the magnitude, pattern and spatial-temporal variation in trends of AET are mainly affected or dominated by climate variables (i.e., precipitation, temperature, solar radiation, wind speed and vapor pressure) (Zou et
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