Droughts can occur all over the world, however there is a link between drought and some climate patterns: A lack of water vapour in the atmosphere means there is less precipitation and more chance of drought.
High-pressure systems reduce evaporation and moisture in the atmosphere. This phenomenon is thought to create droughts in Indonesia and Australia. Causes of droughts There are three main types of drought: Meteorological drought - when the amount of precipitation received in a specific area is less than the average.
Hydrological drought - when reduced precipitation impacts on water supply, eg there is decreased streamflow, soil moisture, reservoir and lake levels, and groundwater. Agricultural drought - when the above two types of drought impact on agricultural activities, eg reduced soil moisture or reservoir levels required for irrigation.
Droughts can also be caused by human activities, for example: Agriculture - using large amounts of water to irrigate crops removes water from lakes, rivers and groundwater. Sunlight, humidity, temperature, and wind affect the rate of evapotranspiration.
When evapotranspiration rates are large, soils can lose moisture and dry conditions can develop. During cool, cloudy weather, evapotranspiration rates may be small enough to offset periods of below-normal precipitation and a drought may be less severe or may not develop at all Moreland, Rainfall in any form will provide some drought relief.
A good analogy might be how medicine and illness relate to each other. A single dose of medicine can alleviate symptoms of illness, but it usually takes a sustained program of medication to cure an illness. Likewise, a single rainstorm will not break the drought, but it may provide temporary relief. A light to moderate shower will probably only provide cosmetic relief.
It might make folks feel better for awhile, provide cooling, and make the vegetation perk up. During the growing season, most of the rain that falls will be quickly evaporated or used by plants.
Its impact is short term. A thunderstorm will provide some of the same benefits as the shower, but it also may cause loss of life and property if it is severe. Thunderstorms often produce large amounts of precipitation in a very short time, and most of the rain will run off into drainage channels and streams rather than soak into the ground. If the rain happens to fall upstream of a reservoir, much of the runoff will be captured by the reservoir and add to the available water supply.
No matter where the rain falls, stream levels will rise quickly and flooding may result. Also, because the rainfall and runoff can be intense, the resulting runoff can carry significant loads of sediment and pollutants that are washed from the land surface. Soaking rains are the best medicine to alleviate drought. Water that enters the soil recharges ground water, which in turn sustains vegetation and feeds streams during periods when it is not raining.
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. Tropical storm rains are usually of the soaking variety, although they may also be intense such as during a thunderstorm and lead to some of the same problems.
Tropical storms often produce more total rainfall than a "regular" soaking rain and can provide longer relief than a single soaking rain. However, tropical rains may also be of such intensity that they exceed the capacity of soil to absorb water and often result in significant runoff and flooding. Tropical rains can help to fill water-supply reservoirs and provide long-term drought insurance.
If significant rainfall does not occur upstream of reservoirs, the drought relief aspects of tropical storms may be of only little consequence. All things considered, a single tropical storm at the right place, at the right time, and with the right amount of rainfall can break a drought. Considering all of the above, even when a drought has been broken it may not be truly over. The benefits of substantial rainfall such as from a tropical storm may last for months, but a return to normal rainfall patterns and amounts is necessary for conditions in streams, reservoirs, and ground water to also return to normal Moreland, Groundwater, which is found in aquifers below the surface of the Earth, is one of the Nation's most important natural resources.
Groundwater is used to provide a large portion of the Nation's population with drinking water, it provides business and industries water for their purposes, and is used extensively for irrigation. The water level in the aquifer that supplies a well does not always stay the same.
Droughts, seasonal variations in rainfall, and pumping affect the height of the underground water levels. If a well is pumped at a faster rate than the aquifer around it is recharged by precipitation or other underground flow, then water levels in the well can be lowered. This can happen during drought, due to the extreme deficit of rain.
The water level in a well can also be lowered if other wells near it are withdrawing too much water. Groundwater decline is a real and serious problem in many places of the Nation and the world.
If streamflow statistics define what a year flood is, do you think similar statistics could define the opposite event — a or year drought? Certainly it can. And, although a drought doesn't have the immediate and devestating impact that a flood has, it can still have severe effects on the local environment just as a flood does only it is drawn out over a longer time period.
As part of the USGS Fisheries program, ecological flows, or the relationships between quality, quantity, and timing of water flows and ecological response of aquatic biota and ecosystems; and related ecosystem services are being investigated.
Phil van Mantgem and his collaborators are using plot-based methods to describe change and vulnerability to drought in the forests of the western United States. A drought is defined as "a period of abnormally dry weather sufficiently prolonged for the lack of water to cause serious hydrologic imbalance in the affected area. The severity of the drought depends upon the degree of moisture deficiency, the duration, and the size of the affected area.
Meteorological -a measure of departure of precipitation from normal. Due to climatic differences, what might be considered a drought in one location of the country may not be a drought in another location.
Agricultural -refers to a situation where the amount of moisture in the soil no longer meets the needs of a particular crop. Socioeconomic -refers to the situation that occurs when physical water shortages begin to affect people.
Lack of rainfall for an extended period of time can bring farmers and metropolitan areas to their knees. It does not take very long; in some locations of the country, a few rain-free weeks can spread panic and affect crops. Before long, we are told to stop washing our cars, cease watering the grass, and take other water conservation steps.
In this situation, sunny weather is not always the best weather. In the desert Southwest, weeks without rain are not uncommon. However, when the weeks turn to months, serious problems can arise. Because of the fact that much of our drinking water comes from snowmelt, a dry winter can have serious implications in terms of how much water is available for the following summer season.
Most locations have sufficient water reservoirs to make it through one dry winter. The real problem becomes back to back dry winter seasons, similar to what is occurring during the period of time.
With two significantly below-normal precipitation winter seasons, reservoirs are becoming low and the fire danger rises as the forests dry out. However, summer rains can alleviate the situation, as the monsoon season typically develops by July. The Dust Bowl days of the 's affected 50,, acres of land, rendering farmers helpless.
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