نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم و مهندسی آب، دانشکده کشاورزی، دانشگاه بوعلی سینا، همدان، ایران.
2 دانشگاه لرستان- استادیار گروه مهندسی آب دانشکده کشاورزی و منابع طبیعی
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
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
کلیدواژهها [English]
Investigating the effects of climate change on reference evapotranspiration based on the SSP scenarios
EXTENDED ABSTRACT
Studies show that climate change can pose a threat to food security, the environment, and economic activities. It can also alter temperature and precipitation patterns in different regions, thereby affecting the hydrological cycle. Evapotranspiration is also an important part of the hydrological cycle, which holds significant importance in water resource management and agricultural planning. Therefore, studying the impact of climate change on the important parameter of reference Evapotranspiration (ETo) plays a crucial role in improving water consumption management on farms and agricultural planning.
In this study, climate data from Khorramabad station for the time range of 1988-2014 was used. Among the GCM models, the MRI-ESM2 from the Japan Meteorological Research Institute was selected as the top model due to its high resolution matching with the synoptic stations in Khorramabad. Using the climate data from this model and the SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5 scenarios under the sixth IPCC report (CMIP6), they were downscaled for the period of 2100-2023 for Khorramabad station. For this purpose, the most effective predictors for temperature and precipitation parameters were first identified using the Weka software, and then, using the neural network model, the monthly average values of 44 years of temperature and precipitation parameters (1970-2014) were separately used for downscaling in the observational station scale (Khorramabad station). It is worth mentioning that 75% of the observational data were used for model training and 25% of the data were used for model testing. Then, using the observational climate data and downscaled minimum and maximum temperature data, reference evaporation and transpiration were calculated for the base period and future period using the Hargreaves-Samani method.
In this study, three time periods were examined: near future (2023-2048), middle (2049-2074), and far (2075-2100). For this purpose, the reference evapotranspiration was calculated for the base period and future periods using the Hargreaves method. The results showed that on average, the maximum temperature in Khorramabad station will increase by 0.26 to 6.3 degrees Celsius and the minimum temperature will increase by 0.32 to 4.9 degrees Celsius compared to the base period (1988-2014) by the year 2100. Also, the average amount of reference evapotranspiration will increase in all periods compared to the observational base period. The amount of reference evapotranspiration in the near future will vary between 4.69 to 4.82 millimeters per day, in the middle future between 4.7 to 4.94 millimeters per day, and in the far future between 4.72 to 5.04 millimeters per day, with the SSP1-2.6 scenario predicting the lowest amount and the SSP5-8.5 scenario predicting the highest amount of reference Evapotranspiration in different time periods.
Based on the results, it can be said that the consequences of climate change, especially in terms of temperature, are observable. According to the seasonal changes in reference evapotranspiration, the results of all SSP scenarios indicate an increase in this parameter during the cold seasons. Therefore, considering the temperature in the increase of evaporation and transpiration, we need to look for solutions for better water resource management and improve water utilization methods, especially in the agricultural sector.
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