资源环境科技发展态势分析平台

Global climate change is likely to affect reference evapotranspiration (ET0) and the use of water resources for vegetation management. Our goals were to identify spatio-temporal characteristics of ET0 and factors controlling the change in ET0 and to project spatio-temporal changes in the Qilian Mountains of China under the future climate conditions. Changes in ET0 were estimated by the Penman-Monteith method for 22 meteorological stations from 1960 to 2015. We quantified the attributions of climatic factors with the differentiation equation method. Then, we assessed the spatio-temporal changes in projected ET0 with CanESM2 model outputs and statistical downscaling model for three representative concentration pathways (RCP) scenarios for years 2016-2100. We found that annual ET0 averaged across the region was 1001.5 mm, with an insignificant decrease of -0.43mm/year during 1960-2015. The lowest values were present in the alpine region in the central area, while the highest ET0 was detected in the western region. An annual and seasonal evaporation paradox existed in the Qilian Mountains during the past few decades. Mean daily air temperature measured (T-mean) and wind speed (U-2) were the dominant factors in ET0 change. However, the decreasing trend in ET0 may be due to a diminished effect of T-mean triggered by short-wave radiation (R-s), actual vapour pressure (e(a)), and wind speed (U-2), but especially by the substantial reduction in U-2 at most stations. Compared with the baseline, ET0 is likely to increase by 6.31-7.20, 6.11-10.41, and 6.58-17.66%, respectively, under RCP scenarios of 2.6 (very low forcing scenario), 4.5 (medium stabilization scenario), and 8.5 (very high emission scenario), but RCP2.6 ET0 rates level off and even decline after 2050 while RCP4.5 rates climb only marginally after 2050. Thus, ET0 projected with the CanESM2 model displayed an upwards trend in the Qilian Mountains, especially the central alpine region.