Drought can be generally defined as a temporary meteorological event, which stems from a deficiency of precipitation over an extended period of time compared to some long-term average conditions. Drought always starts with a shortage of precipitation (compared to normal or average amounts), but may (or may not, depending on how long and severe it is) affect streams, soil moisture, groundwater, etc. It is a recurring natural event and a normal part of the climate of all world regions, regardless of how arid or humid they are. Droughts develop slowly, are difficult to detect and have many facets in any single region. It is, thus, one of the most complex natural phenomena, that is hard to quantify and manage, and has multiple and severe social and economic impacts.
The magnitude of these impacts is determined by the level of development, population density and structure, demands on water and other natural resources, government policies and institutional capacity, technology, and the political system. These points of departure set the scene and scope for this study.
This study examines the global patterns and impacts of droughts through mapping several drought-related characteristics – either at a country level or at regular grid scales. Characteristics cover various aspects of droughts – from global distribution of meteorological and hydrological drought risks to social vulnerability and indices related to water infrastructure.
The maps are produced by integrating a number of publicly available global datasets. The subsequent analysis of maps allows a number of policy relevant messages to be extracted. It appears that arid and semi-arid areas also tend to have a higher probability of drought occurrence. The report points out that in drought years, the highest per capita loss of river flow occurs in areas that do not normally experience climate–driven water scarcity.
This study also illustrates that the African continent is lagging behind the rest of the world on many indicators related to drought preparedness and that agricultural economies, overall, are much more vulnerable to adverse societal impacts of meteorological droughts. Regions with an unreliable and vulnerable nature of river discharge, and having the largest drought deficits and durations are highlighted, pointing to the danger of focusing on drought mitigation measures on river flows alone. The ability of various countries to satisfy their water needs during drought conditions is examined using storage-related indices.
The study used a number of publicly available datasets ranging from demographics and socioeconomics to natural resources and climate. The datasets used are listed below.
IWMI Research Report 133 - Mapping Drought Patterns and Impacts: A Global Perspective
For further information contact:
Nishadi Eriyagama or GIS, RS and Data Management Unit
International Water Management Institute
