عنوان مقاله [English]
Background and objectives: In the recent years, increase of temperature due to increase of greenhouse gases have led to anomaly in the Earth’ climate system. Due to the importance of climate change and its effects, and in order to plan for adaptation to climatic variations, prediction of atmospheric variables has been done by scientists using different models. The objectives of this study were to analyze the annual rainfall and temperature trends, compare the results of fifth report of Intergovernmental panel with each other and determine the changes in rainfall and temperature in future periods compared to the base period at the annual and monthly scale, and estimated water requirement of date palm in Ahwaz area.
Materials and methods: In this research, downscaling method was done using SDSM model by using fifth report of Intergovernmental panel on climate change (IPCC) under new emission scenarios. Climate Change models under new three models scenarios namely RCP2.6, RCP4.5 and RCP8.5 under three future periods: near-century (2010-2040), mid-century (2041-2070) and late-century (2071-2099) were investigated and compared for Ahwaz station. Daily rainfall observations, average, minimum, and maximum temperatures for the period 1966-2001 were inputs of model.
Results: The results of the output of the downscaling methods showed that in the future periods, on the three scenarios studied, the temperature increase and precipitation will decrease in Ahvaz station. In the different scenarios, the lowest temperature rise was in June with 0.95 degrees Celsius under RCP 8.5 and the highest temperature rise in September with 3.96 degrees Celsius under RCP 4.5 during 2011- 2040. The lowest average annual temperature rise was 1.96 degrees Celsius under RCP 8.5 scenario and the highest average annual temperature rise was 2.57 degree Celsius under RCP 4.5 during 2011-2040. The lowest temperature rise in December with 3.13 degrees Celsius under RCP 2.6 and the highest temperature rise in September with 5.57 degrees Celsius under RCP 4.5 during 2041- 2070. The lowest average annual temperature rise was 3.18 degrees Celsius under RCP 2.6 scenario and the highest average annual temperature rise was 4.65 degree Celsius under RCP 8.5 during 2041-2070. The lowest temperature rise in January with 1.58 degrees Celsius under RCP 2.6 and the highest temperature rise in September with 6.62 degrees Celsius under RCP 8.5 during 2071- 2099. The lowest average annual temperature rise was 4.27 degrees Celsius under RCP 2.6 scenario and the highest average annual temperature rise was 5.99 degree Celsius under RCP 8.5 during 2071-2099. The results of water requirement with using CropWat 8 software at showed that the required water content in the period 2040-2011 in the scenario (RCP2.6) decreased by 0.4 and under Two other scenarios increased. The required water requirement for 2041-2070, as well as 2071-2099, increased.
Conclusion: Due to the increase in temperature and the decrease in rainfall during the upcoming periods, the water requirement for Date palm will increase in Ahwaz region.