assessing stream flow regime and basin water storage in occurrence of hydrological drought in lorestan province

The objectives of this study were to apply base flow index (bfi) for assessing stream flow regime and basin water storage and to validate this index in drought studies in lorestan province. to view of this, daily bfi and mean of annual bfi were calculated based on the minimum 5-day periods in 24 gauging stations with period 35 years. the results showed that the regional mean of bfi with 0.77 value (sd=0.08) is stable. bfi ranged between 0.61 and 0.95 and also based on the 25, 50 and 75 percentiles river flow regime in the study area divided to four categories that most of catchments in the study area have stable regime. so the catchments will be able to provide river flow during dry weather. therefore, the results of this study can be used in classification of stream flow regime of river and hydrological drought monitoring.