Global Drought Hazard Frequency, Distribution, and Risks, 1980-2000

This data set is part of the Natural Disaster Hotspots Collection of global geospatial data of six major natural hazards (earthquakes, volcanoes, landslides, floods, drought, and cyclones). It provides a 2.5 minute grid based upon the International Research Institute for Climate Prediction's (IRI) Weighted Anomaly of Standardized Precipitation (WASP). Utilizing average monthly precipitation data from 1980 through 2000 at a resolution of 2.5 degrees, WASP assesses the precipitation deficit or surplus over a three month temporal window that is weighted by the magnitude of the seasonal cyclic variation in precipitation. The three months' averages are derived from the precipitation data and the median rainfall for the 21 year period is calculated for each grid cell. Grid cells where the three month running average of precipitation is less than 1 mm per day ae excluded. Drought events are identified when the magnitude of a monthly precipitation deficit is less than or equal to 50 percent of its longterm median value for three or more consecutive months. Grid cells are then divided into 10 classes having an approximately equal number of grid cells. Higher grid cell values denote higher frequencies of drought occurrences. Also included are 2.5 minute grids representing the associated risks of mortality and economic loss from these hazards. Risk levels are estimated by combining hazard exposure with historical vulnerability for two indicators of elements at risk (gridded population and Gross Domestic Product (GDP) per unit area) for each of the six natural disaster hazards. The risk levels are conveyed at sub-national scales and can be used to inform a range of disaster prevention and preparedness measures, including prioritization of resources, targeting of more localized and detailed risk assessments, implementation of risk-based disaster management and emergency response strategies, and development of long-term land-use plans and multi-hazard risk management strategies.