Analysis and forecasting drought, evapotranspiration and green water changes in Urmia Lake Basin under climate change

Sustainable development of agriculture is facing with several challenges such as climate change resulting change in the pattern of weather parameters as well as crop water requirements. In this research, due to the important role of agricultural activities whitin Urmia Lake Basin in the production of various agricultural products such as wheat, the possibility of supplying the plant's water requirement from green water and drought and evapotranspiration (ET) changes under climate change were investigated. Using the SDSM model and baseline meteorological data (1967-2015) of Tabriz and Urmia stations, meteorological data for the future period (2016-2100) was projected under RCP2.6 and RCP8.5 scenarios. Reference ET and the severity of drought were assessed by using the FAO-Penman-Monteith equation and the SPI drought index, respectively. The SDSM model had a relatively good performance and accuracy in estimating rainfall and ET in the study area. The findings of the study indicated an increase of 63 and 3% in the average rainfall of the future period for Tabriz and Urmia stations, respectively, and a reduction in severity of drought compared with baseline period. Under climate change, the average of annual ET of Tabriz and Urmia stationswill be decreased by 3 and 1.5%, respectively, and the amount of green water will be increased.