Drought monitoring involves observing indicators and indices that evaluate changes in a region’s hydrological cycle . Indicators, which are used to describe drought conditions, are variables such as precipitation, temperature, streamflow, ground and reservoir water levels, soil moisture, and snowpack.
Are we still in a drought 2021?
Almost half of the United States is currently experiencing some level of drought , and it is expected to worsen in upcoming months. ... The map above, built with data from the U.S. Drought Monitor, depicts areas of drought in the continental U.S. on March 23, 2021.
What tools are used to measure droughts?
One of the most common tools to measure drought is the Palmer Drought Severity Index (PDSI) . The PDSI was originally developed by Palmer [1965] with the intent to measure the cumulative departure in surface water balance.
How is drought measured and monitored?
The Palmer Z-Index measures short-term drought on a monthly scale . The Palmer Crop Moisture Index (CMI) measures short-term drought on a weekly scale and is used to quantify drought’s impacts on agriculture during the growing season. ... The hydrological impacts of drought (e.g., reservoir levels, groundwater levels, etc.)
How does the drought Monitor Work?
Traditional ways to measure drought are by comparing observed precipitation with what’s normal (climatologic) , by comparing soil moisture and crop conditions with what’s normal (agricultural), or by looking at how much water is contained in snow, the level or flow rate of moving water, water in reservoirs, or ...
How does a drought end?
The only way a drought can really end is with enough regular soaking rains or significant snow . Rains that soak into the soil can replenish the groundwater. Groundwater provides water to plants and can refill streams during non-rainy periods. One soaking rain may help improve drought conditions.
How many types of droughts are there?
As a result, the climatological community has defined four types of drought: 1) meteorological drought, 2) hydrological drought, 3) agricultural drought, and 4) socioeconomic drought. Meteorological drought happens when dry weather patterns dominate an area.
What causes a 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.
What are effects of drought?
Drought can also cause long-term public health problems, including: Shortages of drinking water and poor quality drinking water . Impacts on air quality , sanitation and hygiene, and food and nutrition. More disease, such as West Nile Virus carried by mosquitoes breeding in stagnant water.
What is considered a severe drought?
The nationwide Drought Monitor categorizes drought into five levels of severity: abnormally dry (category D0, corresponding to a PDSI
What states have no 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.
Are there varying degrees of drought?
The USDM’s drought intensity scale is composed of five different levels : D0, D1, D2, D3, and D4. The abnormally dry category, D0, corresponds to an area experiencing short-term dryness that is typical with the onset of drought. This type of dryness can slow crop growth and elevate fire risk to above average.
How much rain is needed to end a drought?
When the PHDI reaches a value equal to or greater than −0.5 , drought ends. And, when the PHDI reaches a value greater than or equal to −2.0, a severe or extreme drought ameliorates.
Will the drought end?
The droughts won’t all end at once . ... Drought experts largely agree that a wet season with strong, above-average precipitation will be enough to moisten the parched grounds in California and the Pacific Northwest, and to refill California’s dropping reservoirs.
How many years does a drought last?
Several weeks, months, or even years may pass before people know that a drought is occurring. The end of a drought can occur as gradually as it began. Dry periods can last for 10 years or more . During the 1930’s, most of the United States was much drier than normal.
What is the longest drought in history?
The three longest drought episodes occurred between July 1928 and May 1942 (the 1930s Dust Bowl drought ), July 1949 and September 1957 (the 1950s drought), and June 1998 and December 2014 (the early 21st-century drought).
