Evaluation of Drought in Western Synoptic Stations Using Herbst and Neuro-Fuzzy Method

Low rainfall and subsequent periods with low flow has profound effects on water resource management. In addition, growing water demand would increase in periods of acute drought conditions is critical. Drought management and water use restrictions, one point is directly a function of drought. In this paper, we evaluate the severity of the drought index using monthly rainfall deficit Herbest and forecast values with ANFIS model in 27 stations in the provinces of West, a 30-year period (1985-2014) were discussed. Drought monitoring results showed that the synoptic stations with 260 months and 122 months Sarab and Kermanshah respectively the highest and lowest number of months were dry. And the maximum relative intensity of drought (Y (dimensionless)) in Maragheh and Jolfa stations 47/3 and 50/2, respectively, were calculated. The highest and lowest values drought index (I) in TAKAB stations, Sarab, Saghez and Sar Pol Zahab and in stations and Lorestan and Ardabil province occurred. Monthly rainfall is also projected deficit amounts (MMD) ANFIS model based on the criteria Nash, coefficient of determination and the error rate than in Kermanshah stations, Mianeh and Piranshahr models showed better performance.