Comparison of evapotranspiration results under climate change RCP scenarios

Abstract

Evapotranspiration after rainfall is the main component of the hydrological cycle that quantifies the amount of water lost. Since climate change directly affects the temperature and rainfall parameters, and the evapotranspiration rate is directly related to the air temperature, it is expected to have significant changes in the future. Therefore, in this research, the possible impacts of climate change on evapotranspiration changes under two RCP2.6 and RCP8.5 climate scenarios are investigated using statistical downscaling model (SDSM) and CanESM2 atmospheric general circulation model output for the future period 2030-2059. Reference evapotranspiration rate was compared with Hargreaves-Samani and Thornthwaite methods in monthly and annual periods for the base and future periods. The results showed a mean increase of annual maximum and minimum temperatures in both scenarios from 0.06 to 0.26 °C compared to the base period. The highest increase was in May by 2.61 °C under the RCP8.5 emission scenario. Overall, the trend of evapotranspiration has been increasing throughout the years. The evapotranspiration in the Hargreaves-Samani method in the RCP8.5 scenario had the highest mean change of 0.08 mm or 2.79%. Although annual changes were not perceptible, as evapotranspiration in the basin reaches its maximum in July, the changes increased by 0.45 mm/day in RCP8.5 scenario. The results of monthly survey can be used in surface and underground water resources management and watershed projects estimating the water needs of plants plus appropriate timing of useful irrigation.

Keywords

• evapotranspiration
• hargreaves–samani
• thornthwaite
• rcp
• canesm2