What is Drought?
Drought is a deficiency of water associated with a lack of precipitation. “It is a condition of moisture deficit that is sufficient to have an adverse effect on vegetation, animals and man over a sizeable area” (USGS – The Hydrology of Drought). When a normal amount of moisture is not available to satisfy an area’s usual water consumption, drought occurs. It begins when soil moisture is so diminished that enough water to replace that lost by transpiration cannot be absorbed by vegetation roots.
In areas that depend on rainfall for their moisture, drought can be defined as a period of insufficient rainfall for normal plant growth. In areas where a large percentage of the surface water comes from melting snowpack, such as in Colorado where this is 80 percent, drought can be defined as: “A period of insufficient precipitation, snowpack and reservoir storage to provide adequate water to urban and rural areas” (Colorado State University Extension and Colorado Climate Center).
Why Study Drought?
Drought can occur locally, regionally or statewide. Its occurrence can be slow and last for many years or it can be a short-lived event. In both cases, the impacts can be significant. The interplay between a natural event, demands for water supply and the economic and environmental impacts that can result leads to drought impacts on society (Colorado State University Extension).
DROUGHT BY STATE
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