عنوان مقاله [English]
Background and objectives: Agriculture is one of the most sensitive sectors in terms of climate change, due to its high dependence on meteorological parameters. By increasing air temperature evaporative power of the atmosphere will be increased and crop growth period will be decreased. Under climate change situation crop yield and crop water requirement will be changed. Changes in these parameters under climate change scenarios can be estimated using simultaneous application of climate change and crop growth simulation models. In this study the impact of climate change on potential evapotranspiration of an autumn crop (barley) and a spring crop (maize) in three stations in different climatic regions of Kermanshah Province for the upcoming period of 2046 – 2064 were examined.
Materials and methods: The study was carried out in three phases. In the first phase meteorological parameters in the future were estimated based on scenarios of A1B, A2 and B1 of HADCM3 climate change model and downscaled using LARS-WG package software. In the second phase reference crop evapotranspiration under current and the future situations was calculated using the FAO Penman-Monteith formula and compared together. In the third phase growth of studied crops were simulated by AquaCrop software using calibrated crop parameters in the region and based on current and future weather data sets. According to the model outputs seasonal evapotranspiration, maximum daily evapotranspiration and length of growth period under current and future climates were compared.
Results: Results of first phase indicated the increasing in the minimum and maximum temperatures and fluctuations in rainfall and sunshine hours compared to the base period (1992 - 2010). Meanwhile, in the future potential reference crop evapotranspiration in all three stations will be increased. According to the results of this study seasonal evapotranspiration of maize in the future will be increased by 25 – 27% in Songhor, 16 – 18% in Kermanshah and 5-7 % in Sarpol_e_Zahab. The estimated maximum daily evapotranspiration of maize in the future will be increased by 37 – 38% in Songhor, 19 – 20% in Kermanshah and 19 -21% in Sarpol_e_Zahab. On the effect of climate change growth period of maize will be decreased by 20, 14 and 10 days respectively in Songhor, Kermanshah and Sarpol_e_Zahab. The trend of changes in the studied parameters for barley was the same as maize but the rate of changes was estimated less.
Conclusion: Results of simulation indicated the increasing of seasonal potential evapotranspiration and maximum daily evapotranspiration and decreasing of crop growth period in all three stations under climate change scenarios. The effect of climate change on studied parameters for both crops in Songhor station (cold region) will be higher than Kermanshah (mild) and much more than Sarpol_e_ Zahab (tropical). In addition, the percentage of changes in evapotranspiration of spring crop (maize) under climate change will be more than winter crop (barley).