Drought | Definition and impacts

Drought | Definition and impacts

Drought is a deficiency in precipitation over an extended period. It is a normal, recurrent feature of climate that occurs in virtually all climate zones. The duration of droughts varies widely. There are cases when drought develops relatively quickly and lasts a very short period of time, exacerbated by extreme heat and/or wind, and there are other cases when drought spans multiple years, or even decades. Studying the paleoclimate record is often helpful in identifying when long-lasting droughts have occurred.

Drought | Definition and impacts

Droughts have significant economic, environmental, and social impacts, both direct and indirect. Many economic impacts occur in agriculture and related sectors, including forestry and fisheries, because of the reliance of these sectors on surface and subsurface water supplies. The web of impacts may become so widespread that it is often difficult to determine accurate financial estimates of damages.

Drought can be defined according to meteorological, agricultural, hydrological, and socio-economic criteria.

Meteorological, when precipitation departs from the long-term normal;

Agricultural, when there is insufficient soil moisture to meet the needs of a particular crop at a particular time. Agricultural drought is typically evident after meteorological drought but before a hydrological drought;

Hydrological, when deficiencies occur in surface and subsurface water supplies;

Socio-economic, when human activities are affected by reduced precipitation and related water availability. This form of drought associates human activities with elements of meteorological, agricultural, and hydrological drought.

General Drought Facts

• Droughts are natural events that occur in nearly all climate zones but with widely variable characteristics.

• Drought is a deviation from climate and is quite different from an arid region with low annual precipitation.

• While droughts can be defined as a climate phenomenon, their impacts on humans and the environment can be extreme.

Direct impacts of droughts

• Reduced crop, rangeland, and forest productivity

• Reduced water levels

• Increased fire hazard

• Damage to wildlife and fish habitat

• Increased livestock and wildlife mortality rates

• Increased insect infestations

• Increased plant disease

• Increased wind erosion

Indirect impacts of droughts

• Reduced income for farmers and agribusiness

• Risk of foreclosures on bank loans to farmers and businesses, who may their assets

• Increased prices for food and timber

• Increased unemployment

• Reduced tax revenues

• Increased crime and insecurity

• Migration


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