As a result, these impacts are out of phase with impacts in other economic sectors. Extended periods without rainfall are common in Omaha, Nebraska (U.S.A.); Fortaleza, Ceará (Brazil); and Darwin, Northwest Territory (Australia), and a definition based on the number of days with precipitation less than some specified threshold is unrealistic in these cases. Drought in general means acute water shortage. The frequency and severity of hydrological drought is often defined on a watershed or river basin scale. If so, vulnerability and the incidence of drought may increase in the future as supply and demand trends converge.Follow the NDMC on social media to receive the latest information and updates about our work. Supply may also increase because of improved production efficiency, technology, or the construction of reservoirs that increase surface water storage capacity. Compounding factors, such as poverty and inappropriate land use, increase vulnerability to drought. It differs from the aforementioned types of drought because its occurrence depends on the time and space processes of supply and demand to identify or classify droughts. Meteorological drought is defined usually on the basis of the degree of dryness (in comparison to some “normal” or average amount) and the duration of the dry period. It is a slow on-set phenomenon caused by a lack of rainfall. The definitions reflect differences in regions, needs, and disciplinary approaches.Meteorological drought is defined usually on the basis of the degree of dryness (in comparison to some “normal” or average amount) and the duration of the dry period. Locations such as Manaus, Brazil; New Orleans, Louisiana (U.S.A.); and London, England, are examples.
Other definitions may relate actual precipitation departures to average amounts on monthly, seasonal, or annual time scales.Agricultural drought links various characteristics of meteorological (or hydrological) drought to agricultural impacts, focusing on precipitation shortages, differences between actual and potential evapotranspiration, soil water deficits, reduced groundwater or reservoir levels, and so forth. For example, in Uruguay in 1988–89, drought resulted in significantly reduced hydroelectric power production because power plants were dependent on streamflow rather than storage for power generation. Hydrological droughts are usually out of phase with or lag the occurrence of meteorological and agricultural droughts. Whenever human demands for water exceed the natural availability of water, the result is drought.Another factor that can affect water supply is a change in water quality.If some of the available water sources become contaminated—either temporarily or permanently—that decreases the supply of usable water, makes the balance between water supply and demand even more precarious, and increases the likelihood of drought.There are three conditions that are generally referred to as drought:Which type of drought people mean when they talk about “drought” often depends on who they are, they kind of work they do, and the perspective that gives them.Farmers and ranchers are most often concerned with agricultural drought, for example, and agricultural drought is also the type of drought that worries people in the grocery and meat business or people in farm communities that depend indirectly on agricultural income for their livelihoods.Urban planners usually mean hydrological drought when they talk about drought, because water supplies and reserves are key components in managing urban growth.The most common use of the term “drought” refers to meteorological drought because that is the drought condition most familiar to the general public and the one most easily identified.The United States Drought Monitor provides regularly updated drought conditions, using for definition "a moisture deficit bad enough to have Meteorological Drought Meteorological drought is defined usually on the basis of the degree of dryness (in comparison to some "normal" or average amount) and the duration of the dry period. Other climatic regimes are characterized by a seasonal rainfall pattern, such as the central United States, northeast Brazil, West Africa, and northern Australia.
Drought is not purely a physical phenomenon that can be defined by the weather. Is demand increasing more rapidly than supply? LiveAbout uses cookies to provide you with a great user experience.