AskDefine | Define drought

Dictionary Definition

drought

Noun

1 a temporary shortage of rainfall
2 a prolonged shortage

User Contributed Dictionary

English

Etymology

''drūġaþ

Pronunciation

  • a UK /ˈdɹaʊt/ /"draUt/

Noun

  1. A period of below average rain fall.

Translations

a period of below average rain fall

References

Extensive Definition

A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region. Although droughts can persist for several years, even a short, intense drought can cause significant damage and harm the local economy According to the UN, an area of fertile soil the size of Ukraine is lost every year because of drought, deforestation and climate instability.

Implications

Drought is a normal, recurring feature of the climate in most parts of the world. Having adequate drought mitigation strategies in place can greatly reduce the impact. Recurring or long-term drought can bring about desertification. Recurring droughts in the Horn of Africa have created grave ecological catastrophes, prompting massive food shortages, still recurring. To the north-west of the Horn, the Darfur conflict in neighboring Sudan, also affecting Chad, was fueled by decades of drought; combination of drought, desertification and overpopulation are among the causes of the Darfur conflict, because the Arab Baggara nomads searching for water have to take their livestock further south, to land mainly occupied by non-Arab farming peoples.
According to a UN climate report, the Himalayan glaciers that are the sources of Asia's biggest rivers - Ganges, Indus, Brahmaputra, Yangtze, Mekong, Salween and Yellow - could disappear by 2035 as temperatures rise. Approximately 2.4 billion people live in the drainage basin of the Himalayan rivers. India, China, Pakistan, Bangladesh, Nepal and Myanmar could experience floods followed by droughts in coming decades. Drought in India affecting the Ganges is of particular concern, as it provides drinking water and agricultural irrigation for more than 500 million people.
The west coast of North America, which gets much of its water from glaciers in mountain ranges such as the Rocky Mountains and Sierra Nevada, also would be affected.
In 2005, parts of the Amazon basin experienced the worst drought in 100 years. A 23 July 2006 article reported Woods Hole Research Center results showing that the forest in its present form could survive only three years of drought. Scientists at the Brazilian National Institute of Amazonian Research argue in the article that this drought response, coupled with the effects of deforestation on regional climate, are pushing the rainforest towards a "tipping point" where it would irreversibly start to die. It concludes that the rainforest is on the brink of being turned into savanna or desert, with catastrophic consequences for the world's climate. According to the WWF, the combination of climate change and deforestation increases the drying effect of dead trees that fuels forest fires. Paradoxically, some proposed short-term solutions to global warming also carry with them increased chances of drought.

Causes

The effect varies according to vulnerability. For example, subsistence farmers are more likely to migrate during drought because they do not have alternative food sources. Areas with populations that depend on subsistence farming as a major food source are more vulnerable to drought-triggered famine. Drought is rarely if ever the sole cause of famine; socio-political factors such as extreme widespread poverty play a major role. Drought can also reduce water quality, because lower water flows reduce dilution of pollutants and increase contamination of remaining water sources.

Stages of drought

As a drought persists, the conditions surrounding it gradually worsen and its impact on the local population gradually increases. Droughts go through three stages before their ultimate cessation:
  1. Meteorological drought is brought about when there is a prolonged period with less than average precipitation. Meteorological drought usually precedes the other kinds of drought.
  2. Agricultural droughts are droughts that affect crop production or the ecology of the range. This condition can also arise independently from any change in precipitation levels when soil conditions and erosion triggered by poorly planned agricultural endeavors cause a shortfall in water available to the crops. However, in a traditional drought, it is caused by an extended period of below average precipitation.
  3. Hydrological drought is brought about when the water reserves available in sources such as aquifers, lakes and reservoirs falls below the statistical average. Like an agricultural drought, this can be triggered by more than just a loss of rainfall. For instance, Kazakhstan was recently awarded a large amount of money by the World Bank to restore water that had been diverted to other nations from the Aral Sea under Soviet rule. Similar circumstances also place their largest lake, Balkhash, at risk of completely drying out.

Drought mitigation strategies

  • Desalination of sea water for irrigation or consumption.
  • Drought monitoring - Continuous observation of rainfall levels and comparisons with current usage levels can help prevent man-made drought. For instance, analysis of water usage in Yemen has revealed that their water table (underground water level) is put at grave risk by over-use to fertilize their Khat crop. Careful monitoring of moisture levels can also help predict increased risk for wildfires, using such metrics as the Keetch-Byram Drought Index or Palmer Drought Index.
  • Land use - Carefully planned crop rotation can help to minimize erosion and allow farmers to plant less water-dependent crops in drier years.
  • Rainwater harvesting - Collection and storage of rainwater from roofs or other suitable catchments.
  • Recycled water - Former wastewater (sewage) that has been treated and purified for reuse.
  • Transvasement - Building canals or redirecting rivers as massive attempts at irrigation in drought-prone areas.
  • Water restrictions - Water use may be regulated (particularly outdoors). This may involve regulating the use of sprinklers, hoses or buckets on outdoor plants, the washing of motor vehicles or other outdoor hard surfaces (including roofs and paths), topping up of swimming pools, and also the fitting of water conservation devices inside the home (including shower heads, taps and dual flush toilets).
  • Cloud seeding - an artificial technique to induce rainfall.

References

External links

drought in Bosnian: Suša
drought in Catalan: Sequera
drought in Czech: Sucho
drought in Danish: Tørke
drought in German: Dürre
drought in Spanish: Sequía
drought in Esperanto: Trosekeco
drought in Persian: خشکسالی
drought in French: Sécheresse
drought in Galician: Seca
drought in Croatian: Suša
drought in Italian: Siccità
drought in Hebrew: בצורת
drought in Lithuanian: Sausra
drought in Hungarian: Aszály
drought in Dutch: Droogte
drought in Japanese: 旱魃
drought in Norwegian: Tørke
drought in Norwegian Nynorsk: Tørke
drought in Polish: Susza
drought in Portuguese: Seca
drought in Romanian: Secetă
drought in Quechua: Ch'akiy
drought in Russian: Засуха
drought in Simple English: Drought
drought in Serbian: Суша
drought in Finnish: Kuivuuskausi
drought in Swedish: Torka
drought in Turkish: Kuraklık
drought in Contenese: 乾旱
drought in Chinese: 干旱

Synonyms, Antonyms and Related Words

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