What are the levels of drought severity?
The map uses five classifications: abnormally dry (D0), showing areas that may be going into or are coming out of drought, and four levels of drought: moderate (D1), severe (D2), extreme (D3) and exceptional (D4).
What is the shortest drought?
drought of 1980-82 The drought of 1980-82 was the least severe and had the shortest duration.
What is an extreme drought?
Extreme Drought (D3): Major crop/pasture losses, extreme fire danger, widespread water shortages or restrictions.
Which state is least affected by drought?
By this scoring system, the most vulnerable states are Oklahoma, Montana, and Iowa, while Delaware, Massachusetts, Connecticut, and California are least vulnerable to drought.
What is the highest level of drought?
The highest category, exceptional drought, or D4, corresponds to an area experiencing exceptional and widespread crop and pasture losses, fire risk, and water shortages that result in water emergencies.
What breaks a drought?
The end of a drought can occur as gradually as it began. A single soaking rain will provide lasting relief from drought conditions, but multiple such rains over several months may be required to break a drought and return conditions to within the normal range.
Where does the water go during a drought?
Where does the water go? Water is lost from the soil by evaporation from the soil surface and by transpiration from the leaves of plants. The combination of these two factors is called evapotranspiration. Water is also lost as it drains through the soil beyond the reach of the plant roots.
Could the Colorado River dry up?
A 2020 study by U.S. Geological Survey scientists found that the Colorado River has declined by about 20% over the last 100 years. Without considerable change the river could continue to dry up, impacting the drinking water, power, and irrigation abilities of communities across the Southwest.
Which states do not have drought?
The lowest level of drought is labeled D0 and the worst and highest level is D4. While some states, including California, Nevada, New Mexico and Utah, have much of their square mileage covered with D4 level drought, one state has no drought at all, according to the Drought Monitor.
Where does all the water go during a drought?
Precipitation that falls on the land enters the groundwater through percolation or travels to streams, rivers, and lakes as runoff. Water in streams and rivers is carried to the oceans, where it evaporates and forms clouds—where the cycle starts all over again!
What is the main cause of drought?
When rainfall is less than normal for a period of weeks to years, streamflows decline, water levels in lakes and reservoirs fall, and the depth to water in wells increases. If dry weather persists and water-supply problems develop, the dry period can become a drought. Learn more: USGS Drought website.