Investigating the effects of climate change on reference evapotranspiration based on the SSP scenarios

Climate change is a phenomenon that affects many natural processes, including the hydrological cycle. Evapotranspiration is also an important part of the hydrological cycle, which is crucial in water resource management and agricultural planning. Since the estimation of evapotranspiration is always associated with uncertainties, this study examines the effects of climate change on the evapotranspiration process at the Crumbed station in Preston province. The study uses the SAP1-2.6, SAP2-4.5, SAP3-7.0, and SAP5-8.5 scenarios according to the Sixth Assessment Report (AR6) in three future time periods: near future (2023-2048), mid future (2049-2074), and far future (2075-2100). The reference evapotranspiration for the base period and future periods is calculated using the Hargreaves method. The results show that the maximum temperature at the Crumbed station will increase by an average of 0.26 to 6.3 degrees Celsius by the year 2100, compared to the base period (1988-2014). The minimum temperature will also increase by an average of 0.32 to 4.9 degrees Celsius during the same period. Additionally, the average evaporation-transpiration in all periods will increase compared to the base period. The average evaporation-transpiration in the near future will range from 4.69 to 4.82, in the mid-term future from 4.7 to 4.94, and in the far future, from 4.72 to 5.04