Investigation of Heteorological Drought in Southern basins of Urmia lake (Case study: Zarrineh rud and Simeneh rud)

In recent years, Urmia Lake faced with declining water level and shrinkig area of Lake due to reduced water inflow from sub basins. The Simeneh Rud and Zarrineh Rud Rivers comprise 51.6 % of the long term total surface water inflow into the Lake. The main aim of this research is investigation climate behavior of basins in view of metrological drought during recent four decates. In this case drought condition was monitored by using Standardized Precipitation Index (SPI) in deferent time scaled in 31 meteorological stations in Southern basins of Urmia Lake. Spatial distribution of drought indices using by geostatics methods including ordinary kriging, Co-Kriging and inverse distance method (IDW) were calculated, and regional drought map zoning were provided for wet and drough years.The results show that studid area experienced two wet period and one drouth period during recent four decates. After domination of 3 years drough and again govering normal condition over basins, drying Urmia Lake was continued because more factors, mainly human activities, beside of climate effects. In many years, the ordinary kriging model was more appropriate than the Co-Kriging and IDW for mapping regional drought.