Evaluation of Climate Change effect on Evapotranspiration and Yield of Rainfed Wheat in Ahar

Climate is one of the basic factors in nature that its change is one of the most important challenges in the current century. The increasing of emission of greenhouse gases is as the most important affecting factor on climate change that leads to change temperature, precipitation and other climatic parameters. Evapotranspiration is one of the important meteorological variables that are influenced by crop characteristics, soil and meteorological parameters, such as temperature, humidity and radiation, and in fact it creates the relationship between important elements of atmosphere and earth. Hence, it is always affected by climate change. In addition, evapotranspiration is one of the most important parameters that effect on crop's yield. Hence, in this present study, we investigated the effect of climate change on evapotranspiration and wheat yield in Ahar County for the future period (2016-2045); for this, we applied HadCM3 general circulation model under A2 emission scenarios. The results showed that due to climate change, evapotranspiration will increase and its variation will be equal to 18.48 millimeters per year, which is 47.1 percent of the annual average of period 1986-1989. Compared to observed and simulated data for base period, the simulated yield average for the future period (2016-2045) will increase. According to weather variables change, the average of yield will increase from 0.954 in the base period to 0.999 tons per hectare in the future period (2016-2045). The increasing of evapotranspiration caused by temperature increasing is the only factor that has a negative effect on yield, which reduces the amount of available water for the plant and has a negative effect on the yield. Therefore, it is recommended that farmers use the natural mulch, like fiberglass and plastic layers, and artificial mulch, like chaff and leaf litter, to reduce evaporation from the soil surface.