A drought is a period of abnormally dry weather that persists long enough to produce a serious hydrologic imbalance, causing, for example, crop damage and shortages in the water supply. The severity of a drought depends on the degree of moisture deficiency, the duration, and the size of the affected area. Drought can be defined four ways:
Meteorological Drought―when an area gets less precipitation than normal. Due to climatic differences, what is considered a drought in one location may not be a drought in another location.
Agricultural Drought―when the amount of moisture in the soil no longer meets the needs of a particular crop.
Hydrological Drought―when the surface and subsurface water supplies are below normal.
Socioeconomic drought ―when water supply is unable to meet human and environmental needs can upset the balance between supply and demand.