Climate change can impact hydrological cycle through changes in precipitation pattern and amount, temperature, evapotranspiration, and run off. Such changes in climatic parameters can subsequently impact agricultural crop production. This study has been conducted with the aim to find relationships between crop yield and evapotranspiration with historical data (1984-2005) and predict crop yield under expected climate changes in the upcoming years in the northeast of Iran (kashafrood basin). Four major crops in this region were selected such as sugar beet, cotton, been, and chickpea. The future precipitation and temperature data are simulated by downscaling outputs of global climate model HadCM3 (A2 scenario) with ASD (Automated Statistical Downscaling) model. Projected temperature under A2 Scenario showed increasing trend for all three time periods. Projected annual precipitation increased by 4.64%, 5.41%, and 2.22% for (2010-2039), (2040-2069) and (2070-2099), respectively. To calculate the reference crop evapotranspiration, the Hargreaves-Samani (1985) equation was applied and validated for this region. The results showed a nonlinear relationship between crop yields and the seasonal evapotranspiration for all selected crops. Based on our results, seasonal evapotranspiration would increase under climate change scenarios for selected crops in study area. On the other hand, crop yield would increase for all crops except sugar beet. For 2070-2099 period, sugar beet yield would decrease in to base line period (1985-2005).

Keywords