Climate change and its effect on agriculture water requirement in Khuzestan plain, Iran

Global climate change is one of important issues interesting to water resources experts in recent decades. Regarding global climate change, temperature and precipitation forecasting can have significant role in decision making and optimum use of water resources. Carried studies in Iran, like other regions of world, show increasing pattern in annual temperature. The present study was designed to survey temperature increase in Khuzestan plain that is located in the southwest of Iran and its effect on potential evapotranspiration and water uses in agriculture. The effect of temperature increase on agriculture water uses in Khuzestan plain was carried out based on analysis of annual temperature time series and theoretical base of evapotranspiration and crop water requirement. Study area includes vast part of Khuzestan province that has 16 meteorological stations in Behbahan, Ahvaz, Dezful and Karkheh regions. Results of analysis of annual temperature time series showed 3.7°C increase in temperature for a 100-year period. Sensitive analysis of water requirement model showed 14, 8, 4 and 2.7% change in potential evapotranspiration per 1% change in temperature, wind speed, sun hours and relative humidity parameters, respectively. Increasing rate of potential evapotranspiration due to temperature increase was 2.04, 2.01, 1.52 and 2.23 mm/year in Behbahan, Ahvaz, Dezful and Karkheh regions, respectively. Also, the increasing rate of wheat water requirement due to temperature increase was 723, 508, 339 and 488 (m 3 /ha) in study regions during the next 50 years.