What is Drought?

Drought is a normal, recurrent feature of climate. It occurs almost everywhere, although its features vary from region to region. Defining drought is therefore difficult; it depends on differences in regions, needs, and disciplinary perspectives. Based on the many definitions that have appeared in the literature, for example, we might define drought in Libya as occurring when annual rainfall is less than 180 mm, but in Bali, drought might be considered to occur after a period of only 6 days without rain! In the most general sense, drought originates from a deficiency of precipitation over an extended period of time, resulting in a water shortage for some activity, group, or environmental sector. Whatever the definition, it is clear that drought cannot be viewed solely as a physical phenomenon.

Understanding and Defining Drought

A discussion of the concept and definition of drought.

Drought Indices

An analysis and discussion of 8 drought indices, also available as a pdf.

Predicting Drought

The multiple causes of drought and their use in drought prediction.

Drought and Climate Change

A short history of the Greenhouse Effect and climate change.

Other Resources

Resources on El Nino and Climate Change

Fortunately, many people are working to plan for drought. Drought planning is a process that focuses on enhancing our abilities to monitor drought, understand our changing drought vulnerabilities, and mitigate drought. By proactively planning for drought, society will be better prepared and able to deal with the damaging effects of drought in the most fair and efficient manner possible.