What Is Drought?
Drought is a normal, recurrent feature of Colorado’s climate but without adequate mitigation and response, it can be very destructive. Drought is a shortage of water associated with a lack of precipitation. It occurs when a normal amount of moisture is unavailable to satisfy an area’s usual water consumption. Drought can appear slowly and last for many years or it can be a short-lived event. It also can occur locally, regionally or statewide. Drought’s impact on society results from the interplay between a natural event, demands for water supply and the economic and environmental impacts that can result.
How Is Drought Classified?
The National Drought Mitigation Center
outlines the following “operational definitions of drought”:
- Meteorological drought is usually an expression of precipitation’s departure from normal over some period of time. Meteorological measurements are the first indicators of drought.
- Agricultural drought occurs when there is not enough soil moisture to meet the needs of a particular crop at a particular time. Agricultural drought happens after meteorological drought but before hydrological drought. Agriculture is usually the first economic sector to be affected by drought.
- Hydrological drought refers to deficiencies in surface and subsurface water supplies. It is measured as streamflow and as lake, reservoir and groundwater levels. There is a time lag between lack of rain and less water in streams, rivers, lakes and reservoirs, so hydrological measurements are not the earliest indicators of drought. When precipitation is reduced or deficient over an extended period of time, this shortage will be reflected in declining surface and subsurface water levels.
- Socioeconomic drought occurs when physical water shortage starts to affect people, individually and collectively. Or, in more abstract terms, most socioeconomic definitions of drought associate it with the supply and demand of an economic good.