The effect of droughts on groundwater and surface water resources and reduced water quality and quantity are available. In advanced stages of drought, water resources are facing a severe shortage. In order to study drought in Gamasyab basin meteorological drought of SPI indices and the SDI, SWSI and SWI Indices are used to assess hydrological drought. The SPI index was calculated by using rainfall data from 16 synoptic stations and rain gauge, for each of the stations on time scales 3،6،12 and 24 months. To calculate the streamflow drought index (SDI), and surface water supply index (SWSI), monthly streamflow data from Hydrometer stations, and the data from piezometric wells for standard water level index (SWI) are used. In this study, for the selection of stations, data period and their regional distribution were considered. As the stations have different available period of data and have a relatively high diversity in space, and since climate studies in the catchment needs to have uniformed period, 21-year period time series from 1992 to 2012 were selected. Cross-correlation in different lag times between each hydrological drought and meteorological drought index is then calculated. In general, it is observed that on a 3-month and 6-month time scales most stations show intermittent drought and wet years. The number and frequency of drought and wet periods is reducing from 3-month to 24-month time scales while the continuing drought and wet years in the opposite has increased. In most stations drought begins in 1995 where severe and important drought in most of these stations happens in the years of 1995-1999 and 2009-2012. All three hydrologic drought indices show a drought period in 2009 and 2012 and this indicates that the area in recent years has experienced a water deficit. That is, the interval fluctuations and changes in precipitation effect on groundwater levels show the biggest changes, and with regard to the zoning maps and lag time between SPI and SWI, varies spatially from East to West and from North to South where the effect occurs with lag of 15 to 25 months. Lag time between the SPI index and SDI in the range of 5 to 11 months and 12 to 14 months has occurred in the output of the basin. The time interval between SPI index and SWSI occurs in average of 12-month. In this basin, the time interval of the rainfall impact on hydrological indices appears to increase, based on lag time from Streamflow drought index (SDI) to surface water supply index (SWSI) and Standard water level index, respectively. The reasons for the lag time in mountainous areas can be physical and geological features, rainfall reduction and drought occurrence in recent years, the increasing agriculture and industry, land use and management in the upstream. With different type of management and exploitation of the current resources and comparing with the reduction of these resources by drought, the natural and unnatural factors affecting the reduction of water resources can be determined so that a better linear programming and integrated watershed management can be identified and basin and intrabasin-scale decision can be applied. Keyword : Hydrological drought, SPI, SDI, SWI, SWSI, Basin Gamasyab, Zoning Lag Time, Cross-correlation