Untangling the effects of climate change and land use/cover change on spatiotemporal variation of evapotranspiration over China

Abstract

• ET showed a slight upward trend over China from 2005 to 2020. • The separate effect of climate change on ET was much more significant than LUCC. • ET was sensitive to Ta, Rn, and WS in humid and high-altitude basins, while sensitive to RH and Pr in relatively dry basins. • Wetlands and forestlands corresponded to higher ET values among all land cover types. Evapotranspiration (ET) is sensitive to environmental factors. Accurate assessment of ET and its response to changing environments have important scientific and practical significance. In the context of global climate change, China has experienced tremendous land use/land cover change (LUCC) processes, leaving its ET dynamics and influencing factors still to be determined. Here, the interannual variation and spatial distribution characteristics of ET over China from 2005 to 2020 were analyzed based on the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model. Then the separate contributions of climate change and LUCC to ET variation were quantified by controlling the LUCC scenario of the PT-JPL model. Results indicated that the PT-JPL model could accurately capture the variation of ET. The average annual ET over China from 2005 to 2020 was 464.52 mm, displaying a slightly increasing trend (0.46 mm·yr −1 ). The regions of ET increase were mainly concentrated in southern, central, and northeastern China. Separating the contributions of climate change and LUCC to ET revealed that climate change has a more significant effect on ET than LUCC. Among the five climatic factors, the contributions of relative humidity and precipitation to ET variation in dry basins were greater than those in humid or high-altitude basins, while temperature, net radiation, and wind speed showed an opposite performance. Net radiation and temperature were identified as the most critical factors affecting ET on the national scale. According to China's LUCC data from 2005 to 2020, the area conversion between forestlands, grasslands, and croplands was more significant than that between other land cover types. Wetlands and forestlands corresponded to higher ET values among all land cover types, and conversion to other land cover types would cause a decrease in ET. This study can support policymaking to improve water use efficiency and optimize water resource management.