Investigation of Crop Evapotranspiration and Precipitation changes under Climate Change RCPs Scenarios in Khouzestan province

Background and Objective: The agricultural sector plays a vital role in the national economy and food production in Iran. In the meantime, due to the country's particular climate and the disproportionate distribution of time and place of precipitation, water cultivation is the main driver of food production. In arid areas such as Khuzestan province, nearly one hundred percent of agricultural production comes from water cultivation. According to the Research Center of the Iran Parliament, in order to meet the food needs until 2030, based on approximate 2600 kcal/day more than 150 billion cubic meters of annual water will be required that is not available in water cart of Iran. In at globalizing world, where problems increase with the effect of warming and climate changes, it seems that decrease in usable freshwater bodies will pose a serious problem. This study intends to investigate climate change impacts on evapotranspiration (ET) of agricultural crop in Khouzestan province in future periods. The importance and urgency of the subject and the limited research done in this regard, the local and regional effects of climate fluctuations on the evapotranspiration of agricultural products are of particular importance. These changes are of great importance, especially in fertile and agricultural areas such as Khuzestan.
Materials and Methods: In this research, climate change impact on precipitation and evapotranspiration of agricultural products in future periods was investigated. In order to investigate climate change impact on ET, the CanESM2 atmospheric general circulation model (GCM) data under two RCP scenarios (IPCC-AR5) were used. In order to downscale CanESM2 model data, SDSM analysis software was used. The data used in this study include precipitation, minimum and maximum temperature and daily average temperature. To determine the feasibility of future periods meteorological data production of SDSM model, calibration and verification was performed for the base periods (1990-2005). Minimum and maximum temperature and precipitation estimated by SDSM method by CanESM2 data in three future periods: 2030s, 2060s and 2090s and compared with historical data. The strategic agricultural products such as wheat, barley, rice, corn and sugar cane were selected for this study. Potential evapotranspiration of these products were used during the cultivation period. According to the fifth report of the Intergovernmental Panel on Climate Change (IPCC) using CanESM2 model under RCP scenarios, meteorological data in the upcoming periods were simulated, the average periods potential evapotranspiration were calculated with information generated in the upcoming periods.
Results: Results showed that temperature on average increases about 4°C in all selected scenarios, this increase is higher in case of RCP8.5 compared to RCP4.5, and precipitation reduce in 2060s and 2090s. Studied Crops ET under RCP4.5 compared to baseline is always less than RCP8.5 scenario. For rice and corn, the average ET increase in 2060s and 2090s is higher than the others.
Conclusion: It can be concluded that studied crop ET will increase in future periods, therefore we should consider that there will be lack of water and less crop production in Khouzestan province. We should change our cultivation periods and cultivate more effective crops in order to increase water efficiency and decrease potential evapotranspiration in some area of Khouzestan province.