Projection of Reference Crop Evapotranspiration under Future Climate Change in Poyang Lake Watershed, China

Reference crop evapotranspiration (ET0) is of great importance in assessing the potential impacts of climate changes on hydrological cycles and the global energy balance. The spatiotemporal change of ET0 and the drought response over Poyang Lake watershed of China from 2011 to 2100 are the main concern in this work. Based on the meteorological data and the output of the general circulation model (GCM) from the Coupled Model Intercomparison Project Phase 5 (CMIP5), we used the Penman-Monteith formula and downscaling model to calculate the history and future ET0 in Poyang Lake watershed, respectively. Major results are drawn as follows. First, the annual average ET0 decreased during 1961-2014 and the average ET0 of the basin is high in the north and south, but low in the middle. The ET0 was most dominated by sunshine duration in the spring, summer, and fall and by relative humidity in the winter. Second, the downscaling model has a good simulation effect, and the GCM data-downscaling simulation results are significantly improved after the deviation correction. Third, under the representative concentration pathway (RCP) 4.5 and RCP 8.5 scenarios, ET0 in the Poyang Lake watershed will increase over the next three periods, with the middle future (2041-2070) as the largest increase period. The spatial distribution of ET0 is generally high in the east and low in the west. Fourth, under the RCP 8.5 scenario, the drought index (DI) of the watershed showed an increasing trend, the seasonal distribution of DI is fall > summer > spring > winter, and the Ganjiang River subbasin will be the key prevention area for future drought risks. The results can provide basic data support for the optimal management of water resources and scientific response to the impact of climate change on agricultural production in the watershed for associated policymakers and stakeholders. (c) 2020 American Society of Civil Engineers.