Simulation and estimation of reference evapotranspiration responsing to climate change in Shiyang River basin

Simulating and estimating the influence of climate change on spatiotemporal characteristics of reference evapotranspiration (ET0) provides support for developing water-saving agriculture and efficient use of water resources. The Penman-Monteith equation is employed to calculate daily ET0 for the 11 meteorological stations located in and around the Shiyang River basin during 1951-2012. While ET0 in 2020 s, 2050 s and 2080 s are downscaled from HadCM3 (Hadley centre Coupled Model, version 3) outputs under A2 and B2 emission scenarios by SDSM (Statistical Downscaling Model). The spatial distribution and temporal trend in ET0 are investigated by Inverse Distance Weighted Interpolation and Mann-Kendall test, respectively. The results show that the annual mean ET0 in the Shiyang River basin is 1 061 mm, the highest values are located in the northeast region, and the lowest values are located in the southwest region. HadCM3 projects an ET0 increase of 6%, 14%, 23% under A2 scenario in the 2020 s, 2050 s and 2080 s, respectively, while it projects an ET0 increase of 7%, 12%, 17% under B2 scenario, an obvious amplification is detect? ed in the southeast region, in 2050s and 2080 s, the ET0 increase under B2 scenario are lower than those under A2 scenario. It will be a significant ET0 increasing trend in the future and after the 2050s.