A natural hazard is a physical event that impacts on people and their environment (Blaikie, et al, 1994) Natural hazards that are based on geomorphology, such as volcanic eruptions or earthquakes often produce instant ramifications. Drought is a hazard based on regional climatic parameters. (Pandey, et al, 2002) The impact of drought can be just as devastating as that of other hazards, however the impact is slower to take affect. Drought often results in secondary hazards such as famine, bushfire, erosion and dust storms. The effect of drought is often felt more by those with higher social and political vulnerability. Drought is more likely to occur in places that are semi arid. Management of drought conditions reflects the need for greater prior knowledge of when drought is approaching. Political and social change is also needed. .
A desert area does not equate to a drought. Drought is caused by climatic conditions that result in "abnormal dryness in a region when the usual rains do not appear- (Abbott, 1999.) There are a number of global climatic systems that influence when and where droughts occur. El Nino Southern Oscillation (ENSO) is the most prominent of these. (Bouma, et al. 1997) ENSO is a system that produces periodic short-term climate changes over the Pacific, on average every 5 years. (Bouma, et al. 1997) According to Bouma disasters triggered by drought are twice as likely to occur in El Nino years. ENSO causes warm water on the eastern side of the pacific to be replaced by cold water. Cold water is less likely to evaporate and hence there is less moisture in the air therefore less rainfall. (Abbott, 1999) The same effect is seen in the Indian Ocean this is known as the Southern oscillation. (Abbott, 1999).
The climatic conditions around the intertropical convergence zone (where trade winds from each hemisphere meet (Abbott, et al. 1999) make droughts common in the tropical zone.