Estimating Irrigation Requirements under Climate Change (Case Study: Yazd-Ardakan Plain)

This study was carried out to investigate climate change impact on cultivated area in the Yaz-Ardakan plain considering the possible alterations of evapotranspiration and irrigation requirements. The data used in the analysis represented two time periods: (i) present, (values for the period 1971–2010), and (ii) future, called year 2030 (values for the period 2011–2030). To predict future climate changes, daily climate data from Yazd Synoptic station for 1971-2010 period have been used. Data including, rain, maximum and minimum temperatures and sun shine hours have been investigated through regional climate models driven by A2 scenario of HadCM3 global climate model using LARS-WG software. Crop evapotranspiration and irrigation requirements for two periods, were estimated following the standard procedure described in the FAO irrigation and drainage paper 56 and CROPWAT software. The results show that the climatic changes should significantly affect the studied area in terms of minimum and maximum temperature and precipitation up to the year 2030. Annual maximum and minimum temperature are projected to increase by 1.19 °C and 1.83°C respectively. In the other hand, mean precipitation increase by 9% in 2010-2030 period compare to present period and the distribution of precipitation will have significant changes, as autumn precipitation decreases, the spring precipitation will have increasing trend. Results of this study showed that, due to higher temperature, crop evapotranspiration and irrigation requirements will be increased up to 7% under climate change conditions.