It's hard to tell when a dry spell becomes a drought. Instead, drought is a slow onset natural disaster, an insidious, creeping phenomenon, hard to recognize with certainty until streambeds are dry and crops have withered. Droughts don't have epicenters or paths; they spread and shift through time and space. Drought doesn't topple buildings and buckle highways, but it destroys crops, setting off an economic ripple effect and imperiling regional food supplies within some developing countries.
IT'S SLOW Most natural hazards are "rapid onset", meaning they happen quickly, with little or no warning. Drought is the primary exception; it is a slow-onset, creeping disaster that takes months to establish itself and may persist for seasons, years, or even decades. Figuring out when a drought starts and stops requires careful monitoring of meteorological and hydrological variables such as precipitation and stream flow. (Please don't skip: Definitions of Drought)
Effects are cumulative, growing in magnitude with each additional day of drought. Impacts may linger for years after normal rainfall resumes.
IT BRINGS OUT THE WORST Unlike other natural disasters, drought tends to drive people apart rather than bring them together. Conflicts between people, communities and governments competing for water are typical of drought. The impacts of drought can also be extremely broad, both spatially and in the variety of economic sectors affected.
IT'S VERY EXPENSIVE Drought costs at least as much as faster-moving disasters. Researchers William Riebsame, Stanley Changnon and Thomas Karl found that the U.S. drought of 1987-89 cost the government and private sector an estimated $39 billion and affected up to 70 percent of the country's population. In comparison, researchers have estimated a worst-case hurricane at $7 billion, and a worst-case earthquake at $30 to $50 billion. Their findings are reported in detail in Drought and Natural Resources Management in the United States: Impacts and Implications of the 1987-89 Drought (Westview Press, 1991).
The State of Texas in 1994 completed an extensive study of whether to have a drought management plan. Projections showed that a severe one-year drought that constrained water supplies by 15 percent could cost the state's economy $15 billion in direct effects, and from $25 to $45 billion in indirect effects. This hypothetical drought is similar to the drought that Texas suffered in the 1950s, although the effects are projected for only one year, and the drought of the 1950s, like many other droughts of record, was a multi-year drought.
IT'S MISUNDERSTOOD AND UNDER ESTIMATED The absence of a precise universal definition of drought makes it harder to figure out whether a region is in drought and, if so, how bad the drought is. As a result, decision makers may be too confused to take action until drought's effects are obvious. Unfortunately, by then it's too late to implement many of the most effective responses.
IT'S WORST EFFECTS ARE INDIRECT The direct effects of drought are less obvious and are spread over a larger geographical area than the effects of other natural hazards. Drought seldom results in structural damage, in contrast to earthquakes, floods, and hurricanes. It also seldom results directly in loss of life.
Deaths associated with drought are usually related to a heat wave or a disruption in food supply leading to malnutrition and, possibly, famine. Drought is one of several physical factors, along with floods and locusts, that may triggerfamine. Social contributors to famine include war, civil strife and institutional failure.
