“…Due to its rainfall-only data requirement, simplicity of calculations, decent reliability, and ability to address a variety of drought related issues, SPI has been used extensively in Turkey (Durdu, 2010;Keskin et al, 2009;Sonmez et al, 2005;Touchan et al, 2005;Turkes and Tatli, 2009), Mediterranean region (Lana and Burgueno, 2000;Lana et al, 2001;Paulo and Pereira, 2006;Salvati et al, 2009;Vicente-Serrano et al, 2004), United States (Budikova, 2008;Guttman, 1999;Hayes, 2000;Hayes et al, 1999;Heim, 2002;Keyantash and Dracup, 2002), and other parts of the world (Edossa et al, 2010;Mishra and Singh, 2009;Ntale and Gan, 2003;Pandey et al, 2008;Patel et al, 2007;Roudier and Mahe, 2010;Stricevic et al, 2011;Zhai et al, 2010).…”