Fields outside Benambra, Victoria, Australia suffering from drought conditions

A drought is an extended period of months or years when a region notes a deficiency in its water supply. Benambra is a small town located 28  Kilometres nbsp(17  mi) north-east of Omeo and 430  For a topic outline on this subject see List of basic Australia topics. Generally, this occurs when a region receives consistently below average precipitation. In Meteorology, precipitation (also known as one class of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric It can have a substantial impact on the ecosystem and agriculture of the affected region. An ecosystem is a natural unit consisting of all plants animals and micro-organisms( Biotic factors in an area functioning together with all of the non-living physical ( Agriculture refers to the production of goods through the growing of plants and fungi and the raising of domesticated Animals The study of agriculture Although droughts can persist for several years, even a short, intense drought can cause significant damage^[1] and harm the local economy^[2] According to the UN, an area of fertile soil the size of Ukraine is lost every year because of drought, deforestation and climate instability. An economy is the realized social system of production exchange distribution and consumption of goods and services of a country or other area The United Nations ( UN) is an International organization whose stated aims are to facilitate cooperation in International law, International security ^[3]

Implications

Lake Chad in a 2001 satellite image, with the actual lake in blue. Lake Chad (in French Lac Tchad) is a historically large shallow lake in Africa, whose size has varied greatly over the centuries The lake has shrunk by 95% since the 1960s. ^[4][5]

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. Desertification is the degradation of land in arid and dry sub-humid areas resulting primarily from human activities and influenced by climatic variations Recurring droughts in the Horn of Africa have created grave ecological catastrophes, prompting massive food shortages, still recurring. The Horn of Africa (alternatively Northeast Africa, and sometimes Somali Peninsula; shortened to HOA) is a Peninsula in East Africa Ecology (from Greek grc οἶκος oikos, "house(hold" and grc -λογία -logia) is the scientific study of The 1984 - 1985 famine in Ethiopia were two famines that occurred simultaneously in Ethiopia, of which the northern is the most prominent The 2006 Horn of Africa food crisis is an acute shortage of food affecting four Horn of Africa countries Somalia, Kenya, Djibouti and 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. The War in Darfur is a military conflict in the Darfur region of western Sudan. Sudan (officially the Republic of Sudan) ( السودان al-Sūdān is a country in northeastern Africa. Chad (Tchad تشاد Tshād) officially known as the Republic of Chad, is a Landlocked country in Central Africa. Desertification is the degradation of land in arid and dry sub-humid areas resulting primarily from human activities and influenced by climatic variations Overpopulation refers to a condition where an Organism 's numbers exceed the Carrying capacity of its Habitat. The War in Darfur is a military conflict in the Darfur region of western Sudan. The araB gene Promoter is a bacterial promoter activated by e L-arabinose binding The Baggara Arabs or Baqqarah ( البقارة) are a nomadic Bedouin people inhabiting Africa from between Lake Chad and the Nile Nomadic people, (from the νομάδες nomádes, "those who let pasture herds" also known as nomads, are communities of people that ^[6]

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. The Ganges (ˈgænʤiːz also Ganga, Devanāgarī: hi गंगा in most Indian languages) is the major river in the Indian subcontinent The Indus River { Sanskrit: सिन्धु Sindhu; Urdu: urd {{Nastaliq سندھ}} Sindh; Sindhi: snd The Brahmaputra, also called Tsangpo-Brahmaputra is a Trans-boundary river and one of the major Rivers of Asia. The Mekong is one of the world’s major Rivers It is the 11th-longest river in the world and 7th longest in Asia The Salween River (သံလွင်မြစ် θànlwìn myiʔ also spelled Salwine) rises in Tibet ( after which it flows through Yunnan The Yellow River or Huang He / Hwang Ho ( Hatan Gol Queen river) is the second-longest river in China (after the Yangtze River) and the ^[7] Approximately 2. 4 billion people live in the drainage basin of the Himalayan rivers. A drainage basin is an extent of Land where Water from Rain or Snow melt drains downhill into a body of water such as a River, ^[8] India, China, Pakistan, Bangladesh, Nepal and Myanmar could experience floods followed by droughts in coming decades. India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National Pakistan () officially the Islamic Republic of Pakistan, is a country located in South Asia, Southwest Asia, Middle East and ( Bengali: বাংলাদেশ inc-Latn Bangladesh) officially Nepal (नेपाल) is a Landlocked country in South Asia. Burma, officially the Union of Myanmar ( pjìdàunzṵ mjàmmà nàinŋàndɔ̀ is the largest country by geographical area in mainland Southeast Asia. Drought in India affecting the Ganges is of particular concern, as it provides drinking water and agricultural irrigation for more than 500 million people. Drought in India has resulted in tens of millions of deaths over the course of the 18th 19th and 20th centuries Water of sufficient quality to serve as drinking water is termed potable water whether it is used for drinking or not Irrigation is an artificial application of water to the soil usually for assisting in growing crops ^[9][10][11]

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. Mountain peaks of the Rocky Mountains The Rocky Mountains, often called the Rockies, are a Mountain range in western North America. The Sierra Nevada ( Spanish for "Snowy Range" is a Mountain range located in the U ^[12][13]

In 2005, parts of the Amazon basin experienced the worst drought in 100 years. ^[14][15] 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. ^[16][17] 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. The National Institute of Amazonian Research (Instituto Nacional de Pesquisas da Amazônia or INPA) is a public educational and Research institution in Manaus Deforestation is the conversion of Forested areas to non-forest land for use such as Arable land, Pasture, urban use logged area or wasteland It concludes that the rainforest is on the brink of being turned into savanna or desert, with catastrophic consequences for the world's climate. Rainforests are Forests characterized by high Rainfall with definitions setting minimum normal annual rainfall between 1750–2000 mm (68-78 inches A savanna or savannah is a Tropical or Subtropical Grassland or Woodland Ecosystem. A desert is a Landscape or region that receives very little precipitation. According to the WWF, the combination of climate change and deforestation increases the drying effect of dead trees that fuels forest fires. Climate change is any long-term significant change in the “average weather” that a given region experiences ^[18] Paradoxically, some proposed short-term solutions to global warming also carry with them increased chances of drought. Use of solar shades is a proposed approach to the Mitigation of global warming through Planetary engineering. Mitigation of global warming involves taking actions to reduce Greenhouse gas emissions and to enhance sinks aimed at reducing the extent of Global warming ^[19]

Causes

Generally, rainfall is related to the amount of water vapour in the atmosphere, combined with the upward forcing of the air mass containing that water vapour. If either of these are reduced,the result is a drought. Factors include:

• Above average prevalence of high pressure systems;
• Winds carrying continental, rather than oceanic air masses (ie. A pressure system is a region of the Earth's atmosphere where air pressure is unusually high or low Wind is the flow of Air or other Gases that compose an Atmosphere (including but not limited to the Earth's) reduced water content);
• El Nino (and other oceanic temperature cycles);
• Deforestation and erosion adversly impacting the ability of the land to capture water; ^[20]
• Climate change has a substantial impact on agriculture^[21] throughout the world, and especially in developing nations. El Niño-Southern Oscillation ( ENSO; commonly referred to as simply El Niño) is a global coupled ocean-atmosphere phenomenon Deforestation is the conversion of Forested areas to non-forest land for use such as Arable land, Pasture, urban use logged area or wasteland Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind Climate change is any long-term significant change in the “average weather” that a given region experiences Climate change and Agriculture are interrelated processes both of which take place on a global scale Developing countries are countries that haven't reached Western-style standards of democratic government free market economy industrialization social programs and human rights guaranties ^[22][23][24]

Consequences

Periods of drought can have significant environmental, economic and social consequences. The most common consequences include:

• Death of livestock. Livestock is the term used to refer (singularly or plurally to a Domesticated Animal intentionally reared in an agricultural setting to produce such as Food
• Reduced crop yields. In Agriculture, crop yield (also known as "agricultural output" is not only a measure of the Yield of cereal per unit area of land under cultivation
• Wildfires, such as Australian bushfires, are more common during times of drought. A wildfire, also known as a wildland fire, forest fire, brush fire, vegetation fire, grass fire, Peat fire, For a topic outline on this subject see List of basic Australia topics. Ladysmith-RFSJPG|right|thumb| Ladysmith NSW RFS fire fighting tanker]]A Bushfire is a Fire that occurs in the bush (collective term for ^[25]
• Shortages of water for industrial users. For other uses of this term see Industry (disambiguation An industry (from Latin industrius, "diligent industrious" ^[26][27]
• Dust storms, when drought hits an area suffering from desertification and erosion
• Malnutrition, dehydration and related diseases. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind Malnutrition is a general term for a medical condition caused by an improper or insufficient diet. Dehydration ( hypohydration) is the removal of Water ( hydro in ancient Greek) from an object
• Famine due to lack of water for irrigation. A famine is a widespread shortage of food that may apply to any Faunal species which phenomenon is usually accompanied by regional Malnutrition, Starvation Irrigation is an artificial application of water to the soil usually for assisting in growing crops
• Social unrest. Unrest is a sociological phenomenon for instance Industrial unrest Labor unrest Rebellion
• Mass migration, resulting in internal displacement and international refugees. Mass migration refers to the migration of a large group of people from one geographical area to another Internally displaced persons (IDPs are people forced to flee their homes but who unlike refugees remain within their country's borders According to the 1951 Convention Relating to the Status of Refugees, a refugee is a person who owing to a well-founded fear of being persecuted for reasons of race
• War over natural resources, including water and food. War is an international relations Dispute, characterized by organized Violence between National Military units
• Reduced electricity production due to insufficient available coolant for power stations^[28] and reduced water flow through hydroelectric dams. Electricity generation is the process of converting non-electrical Energy to Electricity. A power station (also referred to as generating station, power plant or powerhouse) is an industrial facility for the generation of Hydroelectricity is electricity generated by Hydropower, ie the production of power through use of the gravitational force of falling water A dam is a barrier that divides waters. Dams generally serve the primary purpose of retaining water while other structures such as Floodgates, Levees ^[29]
• Snakes have been known to emerge and snakebites become more common. A snake is an elongate Reptile of the suborder Serpentes Like all reptiles snakes are covered in scales. ^[30][31]
• Creates windblown dust bowls which erodes the landscape, damages terrestrial and aquatic wildlife habitat

The effect varies according to vulnerability. Landscape comprises the visible features of an area of land including physical elements such as Landforms living elements of flora and fauna abstract elements such as lighting 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- lado ma put ti halla igriited hunch. Subsistence agriculture is self-sufficient farming in which farmers grow only enough food to feed the family and to pay taxes or feudal dues 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. Pollution is the introduction of contaminants into an environment that causes instability disorder harm or discomfort to the physical systems or living organisms they are in

Stages of drought

Ship stranded by the retreat of the Aral Sea. The Aral Sea ( Kazakh: Арал Теңізі Aral Tengizi, Orol dengizi Russian: Аральскοе мοре Tajik / Persian: Daryocha-i

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:^[32]

1. Meteorological drought is brought about when there is a prolonged period with less than average precipitation. Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary Meteorological drought usually precedes the other kinds of drought.
2. Agricultural droughts are droughts that affect crop production or the ecology of the range. Agriculture refers to the production of goods through the growing of plants and fungi and the raising of domesticated Animals The study of agriculture Population distribution redirects here For the probability distribution of a statistical population see Probability distribution and Statistical population 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. Soil, often typeset as SOiL, is a four piece rock band from Chicago Illinois United States founded by Shaun Glass Tom Schofield Tim King and Adam Zadel 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. Hydrology (from Greek Yδωρ hudōr, "water" and λόγος logos, "study" is the study of the movement distribution and quality of An aquifer is an underground layer of Water -bearing Permeable rock or unconsolidated materials ( Gravel, Sand, Silt, or Clay A lake (from Latin lacus) is a Terrain feature (or Physical feature) a body of Liquid on the surface of a world that is localized to the A reservoir is most broadly a place or hollow vessel where Fluid is kept in Reserve, for later use Statistics is a mathematical science pertaining to the collection analysis interpretation or explanation and presentation of Data. In Mathematics, an average, or central tendency of a Data set refers to a measure of the "middle" or " expected " value of 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. Kazakhstan, also Kazakstan ( Қазақстан, Qazaqstan, qɑzɑqˈstɑn Казахстан, Kazakhstán,) officially the The World Bank is an internationally supported Bank that provides financial and technical assistance to developing countries for development programs (e The Aral Sea ( Kazakh: Арал Теңізі Aral Tengizi, Orol dengizi Russian: Аральскοе мοре Tajik / Persian: Daryocha-i A soviet (сове́т, "council" originally was a workers' local council in late Imperial Russia. ^[33] Similar circumstances also place their largest lake, Balkhash, at risk of completely drying out. Lake Balqash ( Kazakh: kk Балқаш Көлі, also Balkhash from the Russian ru Озеро Балхаш) is a Lake in southeastern ^[34]

Drought mitigation strategies

• Desalination of sea water for irrigation or consumption. Desalination, desalinization, or desalinisation refers to any of several processes that remove excess salt and other Minerals from Water
• 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. Yemen ( Arabic: اليَمَن al-Yaman officially the Republic of Yemen ( Arabic: الجمهورية اليمنية al-Jumhuuriyya The water table is the level at which the ground water pressure is equal to Atmospheric pressure. KHAT (1210 AM) is a Radio station broadcasting a Sports format ^[35] Careful monitoring of moisture levels can also help predict increased risk for wildfires, using such metrics as the Keetch-Byram Drought Index^[36] or Palmer Drought Index. The Keetch-Byram Drought Index ( KBDI) created by John Keetch and George Byram in 1968 for the United States Department of Agriculture 's Forest Service The Palmer Drought Index, sometimes called the Palmer Drought Severity Index and often abbreviated PDSI, is an often-used measurement of dryness based on recent
• Land use - Carefully planned crop rotation can help to minimize erosion and allow farmers to plant less water-dependent crops in drier years. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind
• Rainwater harvesting - Collection and storage of rainwater from roofs or other suitable catchments. Rainwater harvesting is the gathering or accumulating and storing of rainwater
• Recycled water - Former wastewater (sewage) that has been treated and purified for reuse. Reclaimed water, sometimes called recycled water, is former Wastewater (sewage that has been treated to remove solids and certain impurities and then allowed
• Transvasement - Building canals or redirecting rivers as massive attempts at irrigation in drought-prone areas. An aqueduct is an artificial channel that is constructed to convey water from one location to another Irrigation is an artificial application of water to the soil usually for assisting in growing crops
• Water restrictions - Water use may be regulated (particularly outdoors). An outdoor water-use restriction is a Ban or other lesser Restrictions put into effect that restricts the outdoor use of water Supplies. 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. Cloud seeding, a form of weather modification, is the attempt to change the amount or type of precipitation that falls from Clouds by dispersing substances ^[37]

See also

• Climate change and agriculture
• Drought in Australia
• Droughts and famines in Russia and USSR
• Food security
• United Nations Convention to Combat Desertification
• Water crisis

References

External links

• National Integrated Drought Information System
• Social & Economic Costs of Drought from "NOAA Socioeconomics" website initiative
• Water scarcity from FAO Water (Food and Agriculture Organization of the United Nations)