Drought
For the term as used in sports, see Drought (sport)A
drought or
an extreme dry periodic climate is an extended period where
water availability falls below the statistical requirements for a region. Drought is not a purely physical phenomenon, but rather an interplay between natural water availability and human demands for water supply.
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Fields outside Benambra, Victoria suffering from drought conditions |
The precise definition of drought is made complex owing to political considerations, but there are generally three types of conditions that are referred to as drought.
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Meteorological drought is brought about when there is a prolonged period with less than average precipitation.
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Agricultural drought is brought about when there is insufficient moisture for average crop or range production. This condition can arise, even in times of average precipitation, owing to soil conditions or agricultural techniques.
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Hydrological drought is brought about when the water reserves available in sources such as aquifers, lakes, and reservoirs falls below the statistical average. This condition can arise, even in times of average (or above average) precipitation, when increased usage of water diminishes the reserves.
When the word "drought" is used commonly, the most often intended definition is meteorological drought. However, when the word is used by urban planners, it is more frequently in the sense of hydrologic drought.
physiological drought:if the plant is in salinity condition the plant cannot take water from soil even the sufficient amount of water present in the soil.
Periods of drought can have significant environmental, economic and social consequences. The most common consequences are:
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Wildfires
*Migration or relocation of those impacted
*Social unrest
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War*
Famine due to lack of water for
irrigation*
Disease*
Thirstloss of agricultural productionThe causes of these problems are complex and relate to increased dependence on external resources (inability to grow crops locally) and lowered quality (and thus
contamination) of remaining water sources among other factors. The quality of national infrastructure can increase or decrease the impact of drought, especially with respect to famine, dramatically.
Three droughts were responsible for over 100,000 starvation deaths. These droughts spurred the migration of much of the population to locations such as
New England, to participate in the
whaling industry.
250,000 to 3.25 million die from drought, starvation and disease.
In the
Ukraine and
Volga regions, 250,000 to 5 million perished from starvation due to drought.
In the
Ukraine,
Kuban and
North Caucasus regions, 5 to 10 million perished; see also
Holodomor.
Famine resulted in over 3 million deaths.
This was the worst drought in the modern history of the area. 34 million farmers were displaced and 5 million people starved.
Three waves of drought during this time are collectively referred to as "the
Dust Bowl". Because of several factors including the coincidence of the dustbowl and the
Great Depression, this drought had a severe impact on the U.S., resulting in entire districts of the American
Great Plains being depopulated as people were forced to leave.
This was less severe than the 1936 drought, and resulted in the deaths of only 2.5 million. However, because of the
war with Japan at the time, the drought may be indirectly linked to many other deaths.
In the past 5 years major drought has struck large parts of Australia and for the first time it has begun to affect the urban population. Desalination Projects have been initiated in
Sydney and the
Gold Coast. Many regions have placed heavy restrictions on water usage and some towns have been forced to import water.
Toowoomba in Queensland has voted on a referendum on using recycled sewage water (which the town rejected). Brisbane is set to be supplied via larger dams, a pipeline and possibly also recycling.
