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close this bookAn Overview of Disaster Management (Department of Humanitarian Affairs/United Nations Disaster Relief Office - United Nations Development Programme , 1992, 136 p.)
close this folderChapter 4. Natural hazards
close this folderCharacteristics of particular hazards and disasters 1
View the document(introduction...)
View the documentEarthquakes
View the documentTsunamis
View the documentVolcanoes
View the documentLandslides
View the documentTropical cyclones
View the documentFloods
View the documentDroughts
View the documentEnvironmental pollution
View the documentDeforestation
View the documentDesertification
View the documentPest infestations
View the documentEpidemics
View the documentChemical and industrial accidents


Causal phenomena

Immediate cause - Rainfall deficit
Possible underlying causes - El Niincursion of warm surface waters into the normally colder waters of South American Pacific); human induced changes in ground surface and soil; higher sea surface temperatures; increase of atmospheric carbon dioxide and greenhouse gases.

General characteristics

The reduction of water or moisture availability is temporary and significant in relation to the norm.
Meteorological drought is the reduction in rainfall and hydrological drought is the reduction in water resources.
Agricultural drought is the impact of drought on human activity influenced by various factors: the presence of irrigation systems, moisture retention capacity of the soil, the timing of the rainfall and adaptive behavior of the farmers.


Periods of unusual dryness are normal in all weather systems. Rainfall and hydrology data must be carefully analyzed with influencing factors in predicting drought, however, advance warning is usually possible.

Factors contributing to vulnerability

Location in an arid area where dry conditions are increased by drought
Farming on marginal lands, subsistence farming
Lack of agricultural inputs to improve yields
Lack of seed reserves
Areas dependent on other weather systems for water resources
Areas of low soil moisture retention
Lack of recognition and allocation of resources to drought hazard

Typical adverse effects

Reduced income for farmers; reduction of spending from agricultural sector; increase in price of staple foods, increased inflation rates, deterioration of nutritional status, famine, illness, death, reduction of drinking water sources, migration, breakup of communities, loss of livestock.

Possible risk reduction measures

Drought and famine early warning systems

Specific preparedness measures

Development of inter-institutional response plan

Typical post-disaster needs

Measures to maintain food security: price stabilization, food subsidies, employment creation programs, general food distribution, supplementary feeding programs, special programs for livestock and pastoralists, complementary water and health programs; rehabilitation

Impact assessment tools

Nutritional surveys, socioeconomic surveys, monitoring of rainfall and hydrological data, satellite imagery.