Assessment, Management and investigation of the effects of climate change on drought in western cities of Iran

Drought is a hazardous phenomenon, as a result of climatic parameters abnormalities. The effects of high and low drought occur in different parts of the country, and its effects are more noticeable in arid and semi-arid regions. One of these areas is western Iran, which has been affected by this phenomenon in recent years. The purpose of this study is drought modelling and investigation in western Iran. To do this, climatic parameters were first used, including precipitation, temperature, sunshine, relative humidity and wind speed in 32 years (1987-2018) at 16 stations in western Iran. For modelling the TIBI fuzzy index, at first, four indices (SET, SPI, SEB, MCZI) were been fuzzy in Matlab software, then the indices were compared and finally, by Vikor multivariate decision-making model was used to prioritize areas affected by drought. The results of this study showed that the impact of rainfall on the drought intensity on the 12-months scale is weaker than the 6-months scale. In the six months, from May 1998 to August 2006, the trend was increasing and then followed the steady pattern, but on a 12-month scale, from August 1995 to December 2001, the trend was increasing and after this month it followed the mostly steady pattern. The highest frequency of drought at 6 and 12-month scale occurred in Ilam station and its lowest was in Sarpule-Zahab station. The T.I.B.I index accurately reflects the four indicators of SET, SPI, SEB and MCZI. Based on the modelling, T.I.B.I fuzzy index showed relative superiority to the SPEI fuzzy index. Finally, according to the Vikor multivariate decision-making method, the Ilam station with a score of 0.99 was more prone to drought occurrence.