The Application of Geostatistics on Drought-Severity Zoning: A Case Study of the Urmia lake Basin in Kurdistan
Drought is one of the most important disasters that has affected many countries and leads to severe economic, social, political, and cultural problems, among others. The awareness, prediction and zoning of drought can considerably reduce the risk of this phenomenon. The purpose of this study is to identify the droughts that happened in the studied area and from that, try and predict upcoming incidents of drought. In this research, the Urmia watershed area, located in the east of the Kurdistan province was studied. By using the SPI index, the annual precipitation data of 30 synoptic stations were analyzed for the period of 1993 to 2013. By using simple kriging (SK), ordinary kriging (OK), and inverse distance method (IDW) with grades 1 and 2, the maps of drought intensity for the droughts that occurred in the Kurdistan province were prepared. The standardized precipitation index was used for each statistical year. The results showed that a higher percentage of statistical years are located in the mild and moderate class of drought. The study of the dry periods by using the SPI index showed that in recent years, while continuing to increase landwards, some of the intensity of the droughts has reduced. The most severe droughts occurred in the region in the years 1998, 1999, 2005, and 2008. According to the results, most of droughts occurred in the Hassan Abad station with 6 event and 12 months respectively.