Drought
Drought is a period or condition of unusually dry weather within a geographic area where rainfall is normally present. During a drought there is a lack of precipitation. Droughts occur in all climatic zones. However, its characteristics vary significantly from one region to another.
Drought usually results in a water shortage that seriously interferes with human activity. Water-supply reservoirs empty, wells dry up, and crop damage ensues. Its seriousness depends on the degree of the water shortage, size of area affected, and the duration and warmth of the dry period. In many underdeveloped countries, such as India, people place a great demand on water supply. During a drought period there is a lack of Water, and thus many of the poor die.
Most precipitation depends on water vapor carried by winds from an ocean or other source of moisture. If these moisture-carrying winds are replaced by winds from a dry region, or if they are modified by downward motion, as in the center of an anticyclone, the weather is abnormally dry and often persistently cloudless. If the drought period is short, it is known as a dry spell. A dry spell is usually more than 14 days without precipitation, whereas a severe drought may last for years.
Statistics indicate that every 22 years a major drought occurs in the United States, most seriously affecting the midwestern states. The drought of 1933-35, during which large areas of the Great Plains became known as the Dust Bowl, is an example of a disastrous drought that took place in the United Staes. The effect of the drought was brought about by overcropping, overpopulation, and lack of relief measures.
Although drought cannot be reliably predicted, certain precautions can be taken in drought-risk areas. These include construction of reservoirs to hold emergency water supplies, education to avoid overcropping and overgrazing, and programs to limit settlement in drought-prone areas. The Southern Africa Development Community monitors the crop and food situation in the region and alerts the people during periods of crisis.
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[edit] Effects of Drought
Drought produces a large number of impacts that affects the social, environmental, and economical standard of living. Its affects spread far beyond the physical effects of drought itself. Water is integral to produce goods and provide certain services.Some direct impacts of drought are reduced crop, rangeland, and forest productivity; reduced water leves; increased fire hazard; increased livestock and wildlife death rates; and damage to wildlife and fish habitat. A reduction in crop productivity usually results in less income for farmers, increased prices for food, unemployment, and migration.
The many effects of drought can be listed as economic, environmental, or social. However, not all impacts of drought are negative. Fortunate agricultural producers located outside the drought area benefit by selling their goods at higher prices.
Drought is also associated with increases in insect infestations, plant disease, and wind erosion. Droughts may cause problems with insects and diseases to forests. Forest fires increase dramatically during periods of droughts
Farmers are not the only ones who suffer from droughts. Retailers who provide goods and services to farmers must deal with reduced business. This later leads to unemployment and loss of tax revenue for the government. The recreational and tourism industries are seriously damaged because tourists do not want to travel to a country that is suffering from a severe water shortage. Shortages of certain goods results in the costly importation of necessary goods from outside the affected area.
[edit] Environmental Impacts
[edit] Damage to animal species
- Reduction and degradation of fish and wildlife habitat
- Lack of feed and drinking water
- Greater mortality due to increased contact with agricultural producers, as animals seek food from farms and producers are less tolerant of the intrusion
- Disease
- Increased vulnerability to predation (from species concentrated near water)
- Migration and concentration (loss of wildlife in some areas and too many wildlife in other areas)
- Increased stress to endangered species
- Loss of biodiversity
[edit] Hydrological effects
- Lower water levels in reservoirs, lakes, and ponds
- Reduced flow from springs
- Reduced streamflow
- Loss of wetlands
- Estuarine impacts (e.g., changes in salinity levels)
- Increased groundwater depletion, land subsidence, reduced recharge
- Water quality effects (e.g., salt concentration, increased water temperature, pH, dissolved oxygen, turbidity)
[edit] Damage to plant communities
- Loss of Biodiversity
- Loss of trees from urban landscapes, shelterbelts, wooded conservation areas
- Increased number and severity of fires
- Wind and water erosion of soils, reduced soil quality
- Air quality effects (e.g., dust, pollutants)
- Visual and landscape quality (e.g., dust, vegetative cover, etc.)
Environmental losses are caused by damages to plant and animal species. Wildlife habitat, and air and water quality are usually damaged due to a lack of water and an increase in forest and range fires. Most of the effects of drought are short-term, and as the drought comes to an end many problems are solved. However, many other environmental effects hinder the area for long periods after the drought is over. For example, wildlife habitat may be ruined through the loss of wetlands, lakes, and vegetation. Some species of animals may be wiped out from the area as well. Other drought-related impactngs include social impacts. Social impacts include health, public safety, conflicts between water users, and reduced quality of life. During droughts many people migrate to areas outside the drought-affected location. When this happens, the area loses a great deal of its population, and thus the area has less financial support. Between 1950 and 1980 the drought of Brazil had a loss of 5.5 million people. This continues to be a significant problem in the economic development of Brazil.
[edit] Types of Drought
Although many erroneously consider it a rare and random event, drought is a normal, recurrent feature of climate. It can occur in virtually all climatic zones, with its characteristics varying significantly from one region to another. Drought is a temporary aberration and differs from aridity since the latter is restricted to low rainfall regions and is a permanent feature of climate.
[edit] Meteorological Drought
Meteorological drought is the amount of dryness and the duration of the dry period. Atmospheric conditions that result in deficiencies of precipitation change from area to area.
[edit] Agricultural Drought
Agricultural drought mainly effects food production and farming. Agricultural drought and precipitation shortages bring soil water deficits, reduced ground water or reservoir levels, and so on. More of these effects can be listed by clicking here. Deficient topsoil moisture at planting may stop germination, leading to low plant populations.
[edit] Hydrological Drought
Hydrological drought is associated with the effects of periods of precipitation shortages on water supply. Water in hydrologic storage systems such as reservoirs and rivers are often used for multiple purposes such as flood control, irrigation, recreation, navigation, hydropower, and wildlife habitat. Competition for water in these storage systems escalates during drought and conflicts between Water users increase significantly.
[edit] Socioeconomic Drought
Socioeconomic drought occurs when the demand for an economic good exceeds supply as a result of a weather-related shortfall in water supply. The supply of many economic goods, such as water, forage, food grains, fish, and hydroelectric power, depends on weather. Due to variability of Climate, water supply is sufficient in some years but not satisfactory to meet human and environmental needs in other years. The demand for economic goods is increasing as a result of increasing population. Supply may also increase because of improved production efficiency and technology.
[edit] Effects of Drought
[edit] Economic
- Loss of national economic growth, slowing down of economic development
- Damage to crop quality, less food production
- Increase in food prices
- Increased importation of food (higher costs)
- Insect infestation
- Plant disease
- Loss from dairy and livestock production
- Unavailability of Water and feed for livestock which leads to high livestock mortality rates
- Disruption of reproduction cycles (breeding delays or unfilled pregnancies)
- Increased predation
- Range fires and Wildland fires
- Damage to fish habitat, loss from fishery production
- Income loss for farmers and others affected
- Unemployment from production declines
- Loss to recreational and tourism industry
- Loss of hydroelectric power
- Loss of navigability of rivers and canals.
[edit] Environmental
- Increased Desertification - Damage to animal species
- Reduction and degradation of fish and wildlife habitat
- Lack of feed and drinking water
- Disease
- Increased predation.
- Loss of wildlife in some areas and too many in others
- Increased Stress to Endangered species
- Damage to plant species
- Increased number and severity of fires
- Wind and water erosion of soils
[edit] Social
- Food shortages
- Loss of human life from food shortages, heat, suicides, violence
- Mental and physical Stress
- Water user conflicts
- Political conflicts
- Social unrest
- Public dissatisfaction with government regarding drought response
- Inequity in the distribution of drought relief
- Loss of cultural sites
- Reduced quality of life which leads to changes in lifestyle
- Increased poverty
- Population migrations
[edit] Mitigation
Because severe drought is often slow in its development, it is relatively easy to tell when one is coming and in areas that are capable, there are several mitigation measures that can be used to reduce the impacts felt by drought.
The most important steps in lessening the effects of drought though are soil and water conservation. By protecting soil, it is better able to absorb precipitation, but it can also help farmers to use less water because it is absorbed and not as much runs off. It also creates less water pollution by the pesticides and fertilizers present in most farm runoff.
- Dams - dams and their associated reservoirs and water sheds supply additional water in times of drought.
- Cloud seeding - an artificial technique that induce precipitation.
- Desalination of sea water for irrigation or consumption.
- Land use - Carefully planned crop rotation can help to minimize erosion and allow farmers to plant less water-dependent crops in drier years.
- Outdoor water-use restriction - Regulating the use of sprinklers, hoses or buckets on outdoor plants, filling pools, and other water-intensive home maintenance tasks.
- 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.
[edit] What do you do during droughts?
During a drought most governments advise the people to drink less water, bathe less often and wash their cars less often. When a drought becomes very serious there is a limit to how much water each person may use. If the amount of water used exceeds then this person is fined or possibly imprisoned. In poor countries international aid frequently has to help out to feed the people and help to prevent a famine.
