Climatolgical, Hydrological and Agricultural Drought investigation using Geographic Information System in Ghozestan province, Iran

Drought is a natural hazard which affect on the social and economic status of the country based on short, medium and long term. Timely and accurate monitoring of droughts is the main purpose of this research in planning to reduce the losses caused by drought. Any delay in the forecasting of droughts, is an obstacles to the correct determination of drought for the affected region. The exact assessment of the drought should be based on determination of three meteorological, agricultural and hydrological drought and then integration of the three droughts will able us to define the occurrence and extent of the drought in one area. In this study, the standardized precipitation index (SPI) and the standard discharge index (SDI) and the normalized difference vegetation index (NDVI) as a representative of vegetation (grassland and dryland) was used for a long period and the information layer was used in a GIS environment. The results showed that different types of drought are not matched in terms of time and space. The results also show that during the period of years with above average rainfall, agricultural drought (grassland and dryland) will dominate and in years with less than average precipitation (drought) conditions, rangeland and dryland will behave more accurate than normal conditions. The research has shown that due to the spatial nature of the drought in large areas, using appropriate spatial and temporal resolution of satellite images, is essential in the better assessment of the drought.