Everything about Drought totally explained
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.
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
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:
Consequences
Periods of drought can have significant environmental, economic and social consequences. The most common consequences include:
Death of livestock.
Reduced crop yields.
Wildfires, such as Australian bushfires, are more common during times of drought.
Shortages of water for industrial users.
Dust storms, when drought hits an area suffering from desertification and erosion
Malnutrition, dehydration and related diseases.
Famine due to lack of water for irrigation.
Social unrest.
Mass migration, resulting in internal displacement and international refugees.
War over natural resources, including water and food.
Reduced electricity production due to insufficient available coolant for power stations and reduced water flow through hydroelectric dams.
Snakes have been known to emerge and snakebites become more common.
Creates windblown dust bowls which erodes the landscape, damages terrestrial and aquatic wildlife habitat
The effect varies according to vulnerability. For example, subsistence farmers are more likely to migrate during drought because they don't 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:
Meteorological drought is brought about when there's a prolonged period with less than average precipitation. Meteorological drought usually precedes the other kinds of drought.
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's caused by an extended period of below average precipitation.
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.Further Information
Get more info on 'Drought'.
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