Types of Drought
Drought occurs across large portions of Africa, often with devastating consequences for food security, water supply, crop production, and livestock. Drought often leads to famine, malnutrition, epidemics, and the displacement of large populations. Together with flooding, drought can significantly impede or erode a country’s economic growth and development. Drought is affected by a changing climate, and current projections indicate that it will become more frequent in the future.
Drought is defined as a persistent and abnormal moisture deficiency that impacts vegetation, animals, and people. There are four types of drought:
- Meteorological drought, which indicates lower precipitation than normal over a period of time.
- Hydrological drought, which defines deficiencies in surface and subsurface water supplies. It affects stream flow, groundwater tables, and reservoir levels. It reflects the effects and impacts of extended meteorological drought.
- Agricultural drought, which reflects root-zone soil moisture deficits and impacts on crop yields. It is usually expressed in terms of the soil moisture needed by a particular crop at a particular time.
- Socio-economic drought, which occurs when the demand for economic goods exceeds supply as a result of meteorological or hydrological drought.
Meteorological drought is the first phase of drought. It usually leads to agricultural drought due to lack of soil water. If precipitation deficiencies continue, hydrological drought develops. The groundwater is usually the last to be affected and the last to return to normal levels.