Droughts

Drought Impacts

Dry conditions can spell disaster if there is an absence of precipitation when it is normally in great demand, or if there is much less precipitation than expected at a given time. Because water supply and precipitation fluctuate greatly across the planet, drought has different meanings in different places depending on user demands. In some locations where daily rainfall is the usual condition, a week without rain could be considered a drought. Because every location has its own criteria for drought conditions, it is difficult to devise a widely applicable quantitative index for drought. The Keetch-Byram Drought Index was designed specifically for fire potential assessment. The Thornthwaite Method is often used to assess relative drought. A modified Palmer Drought Index is used to develop a generalized map of abnormally dry crop conditions.

Susceptibility to drought depends on location as well as the age, income, and education level of a particular population. Other factors include level of disaster preparedness, health sector responses, and environmental degradation. In areas already suffering from desertification, drought events are associated with dust storms and respiratory health effects. Overall food consumption is reduced as a result of drought, which can lead to micro-nutrient deficiencies; diets in drought-stricken areas have been found to be lacking in adequate vitamins and minerals. The probability of acquiring and possibly dying from an infectious disease is increased due to malnutrition. Other drought-related factors that can result in an increased risk for infectious disease outbreaks include the contamination of drainage canals, lakes, and small rivers due to standing water and stagnation. Drought and the associated inability to earn a living often cause mass migrations of poor farmers from the rural countryside to already crowded urban centers. These population shifts subsequently lead to a rise in communicable diseases and death because of water, food, and shelter shortages. For those regions of the world with high cases of human immunodeficiency virus and acquired immune deficiency syndrome (HIV/AIDS), the effect of drought on nutrition is amplified, and rural-to-urban out-migrations are believed to spread the threat of HIV/AIDS. The spatial distribution, intensity, and seasonality of epidemic meningitis appear to be strongly linked to drought, along with other climatic and environmental factors.

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