Types of Disasters and Their Consequences

American Public Health Association 

In This Article


Drought affects more people than any other environmental hazard, yet it is perhaps the most complex and least understood type of all environmental hazards. Drought is often seen as the result of too little rain and used synonymously with famine. However, fluctuation in rainfall alone does not cause a famine. Drought often triggers a crisis in the arid and semi-arid areas, since rain is sparse and irregular, but alone does not cause desertification. The ecosystem changes leading to desertification are all attributed to human activities, such as overcultivation, deforestation, overgrazing, and unskilled irrigation. Each of these activities is exacerbated by increasing human populations. The first three activities strip the soil of vegetation and deplete its organic and nutrient content. This leaves the soil exposed to the eroding forces of the sun and the wind. The subsoil that is left can become so hard that it no longer absorbs rain, and the water flows over the surface, carrying away the little topsoil that might have remained.

Displaced populations suffer high rates of disease due to stress of migration, crowding, and unsanitary conditions of relocation sites. Morbidity and mortality can result from diarrheal disease, respiratory disease, and malnutrition. Mortality exceeding a baseline rate of one death per 10,000 people per day is the index of concern. Low weight to height is identified through the percentage of children two or more standard deviations (z-score) from the reference median compared with mean z-scores; children with edema are severely malnourished.

  • Monitor health and nutritional status by assessing weights and heights.

  • Assess and ensure food security, including availability, accessibility, and consumption patterns.

  • Monitor death rate.

  • Ensure safe water, sanitation, and disease control.


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