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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

The spread of farming and grazing
Firewood collection
Timber harvesting

General characteristics

Contributes to other hazards by
- removing root systems which stabilize soil, acting as a filter and buffer, allowing percolation of water into soil and retaining moisture in soil.
- removal of leaf biomass and forest products
- burning and decay of dead wood.


An increase in global focus on the hazard is expanding data base leading to an increased awareness of the problem and to identifying where the problem exists. Overall, the global trend is decreasing as conservation measures are enacted but destruction of forests is rising at alarming rates in some countries.

Factors contributing to vulnerability

Dependence on wood for fuel and income
Unregulated logging and land clearance
Rapid population growth
Rapid expansion of settled or industrialized areas

Typical adverse effects

Deforestation results in loss of free products from the forest such as fruits and medicines, and decline in traditional cultures. It stresses economies which import forest products and are dependent on wood products. It contributes to other hazards, such as:

Flooding - Deforestation of watersheds can increase severity of flooding, reduce streamflows, dry up springs in dry seasons and increase sediment entering waterways.
Drought - Removal of roots and leaf canopy can alter moisture levels drying soil and decreasing precipitation.
Famine - Decrease in agricultural production due to erosion of topsoil and collapse of hillsides may lead to food shortages.
Desertification - Deforestation and removal of vegetation lead to soil compaction and reduction of land productivity.
Environmental pollution - Increases contamination of soil and water and reduces carbon dioxide absorption capacity. Burning of forests and decay of trees releases carbon dioxide to the air, possibly contributing to global warming.

Possible risk reduction measures

Protection of forests through management, legislation, conservancies

Specific preparedness measures

Education of the communities
Promoting alternatives to fuelwood
Soil conservation measures

Impact assessment tools

Forest mapping by use of aerial or remote sensing or ground surveys. Monitoring of reforestation programs.