Drought evaluation of Eghlid region in Fars province using the SWI and RAI indices

The present study was proposed to evaluate severity of drought in Eghlid region where in Fars province. For this purpose, standardized water level index (SWI) and rainfall anomaly index (RAI) were used during a 10 years’ statistical wet period (1384 to 1393) by using monthly water table depth data of 107 pezometric wells and monthly precipitation data of 10 meteorological and synoptic stations. In order to resolve defects of precipitation data, using SPSS software, the correlation coefficient through stations was analyzed and restored with ratios approach method. For determining severity of drought both of data sets of drought indexes were calculated by Excel software in 3, 6, 12, 24 and 48 monthly periods. Five of the biggest occurred droughts were determined in each index and its mutual index and droughts zoning were accomplished using inverse distance weighted (IDW) in ArcGIS program. The results indicated that severity of droughts were increased in recent years. Furthermore, the results are implicating which there is a time delay between hydrological and meteoric drought indexes, in fact it was observed that by calculating the correlation coefficient between the indexes for south and west of Eghlid, the time delay is 2 to 4 years.