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| Succulent plants are
well-adapted to survive long periods of drought. |
Drought
Drought is a continuous period of dry weather when an
area gets less than its normal amount of rain. Droughts
can last months or even years. Because crops and other
plants need water to grow and land animals need water to
live, droughts can be dangerous. Because of the lack of
water, famine occurs and sometimes deserts are created.
Many people die every year in famines that are due to
drought in subsistence farming areas. Sometimes
conflicts can occur because of drought.
A drought is a natural event that is caused by other
weather events like El Niño, high pressure systems, and
global warming. Drought can be triggered by people as
well. Deforestation (people cutting down trees in
forests and not replanting more trees), diverting
(redirecting) rivers, and emptying lakes are ways that
man interferes with nature and can cause drought.
It is often difficult to determine a specific time when
a drought started because a drought is a disaster that
usually takes place slowly. Its effects often build up
slowly over a long time and may last from months to
years, even after rain resumes. |
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Causes of drought
Lack of Rain (precipitation)
Water can fall in three ways from the sky: |
- Water that falls as a liquid and
stays a liquid
- Water that falls as a liquid and
freezes when it touches the ground
- Water that is already frozen and
falls as ice.
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Droughts occur mainly in areas where the normal levels of
rainfall are already low. If it rains a little less than
normal over time, a drought will happen. Wind can also be
one of the factors in a drought when there is already a lack
of rain. If a dry wind blows (like a wind from over the
land) rather than a more humid wind (like a wind from over
the ocean), it can dry the land faster. |
 |
| Fields outside
Benambra, Victoria, Australia suffering from
drought conditions in 2006. |
Dry season
In the tropics (the areas of the earth that are closest to
the equator), there are distinct wet and dry seasons. During
the wet seasons, the area becomes a Monsoon trough because
monsoons are pulled into the movement of air. During the dry
seasons, the Intertropical Convergence Zone (Monsoon trough)
moves dry air through the tropics. The movement of dry air
eventually causes watering holes and rivers to dry up. This
means that many grazing animals like zebras, elephants, and
wildebeest are faced with a choice: move (migrate) to where
there is water or die. The fruit and vegetable-bearing
plants that are left ripen faster because evaporation and
transpiration from the plants are increased. Bushfires are
common during the dry season as well because of the lack of
water in the remaining plants.
El Niño
El Niño is a natural event that takes place when seawater
temperature rises in the tropical Pacific Ocean. This
changes the atmospheric pressure between the Pacific and
Indian Oceans. Since atmospheric pressure determines
weather, during El Niño we see drought in some areas of the
world and heavy rainfall in other areas.
Erosion and human activities
Erosion is a process in which natural forces like wind, air,
water, and gravity cause the earth to move or wear away. In
dry, or arid, climates, the main source of erosion is the
wind. Because the soil is already dry, wind can lift small
particles and move them to another region. Particles that
are suspended in the wind may rub against solid objects and
cause erosion by abrasion. Wind erosion usually happens in
areas where there is not enough rainfall to grow many
plants.
Loess is a type of soil that is affected by wind erosion. It
looks like little cliffs of sand and is common in the middle
of the United States and other areas of the world like
China, Hungary, and Belgium. Windbreaks (like large trees
and bushes) are planted on and near loess to help block as
much wind as possible.
Climate change
Scientists expect that because of global climate change,
droughts will be triggered. Overall, they state that global
warming will result in more rain falling all over the world,
but areas that are prone to drought will increase as well.
Some of the suggestions to fight global warming, however,
involve the use of a space sunshade, which may also increase
the chances of drought. |
|
Types of drought
As drought continues, the conditions surrounding it
gradually worsen and those living in drought areas are
more affected. People define droughts in three main
ways: |
- Meteorological drought happens when
there is a prolonged time that an area receives less
than its average precipitation. Meteorological drought
usually comes before other kinds of drought.
- Agricultural drought affects crop
production or the ecology of a distinct area. This can
happen because of poorly planned farming areas. The
water that is available in the area has a hard time
reaching the plants or erosion occurs. Meteorological
drought conditions can affect agriculture as well.
- Hydrological drought happens when
the water in reserves like aquifers, lakes, and
reservoirs drop below their normal amount. We see the
effects of hydrological drought more slowly because it
involves stored water that is used or moved but not
refilled. This can be caused by people using or moving
water or by a lack of rainfall.
|
Consequences of drought
The consequences of droughts and water shortages can be
divided into three groups: |
- Environmental: Water levels drop and
there is a lower flow of water. This lack of water is
dangerous for animals that live in water. We see more
pollution on the surface of the water. Wetlands dry out,
causing more and larger fires. Wind erosion happens more
easily, and plant life has a hard time surviving because
of lack of water, pests, and diseases. Animals have to
move because of the lack of water and plants.
- Economic: Farming is less successful
during a drought, which means the price of groceries is
affected because there is less food to sell. Livestock
is more difficult to care for during a drought. Forests
have fewer healthy trees and fewer animals. Energy
production decreases in hydro plants (businesses that
use water to make energy). Tourism even decreases
because activities that involve water have a harder time
working correctly.
- Social: People's health can be
affected by heatwaves and having to use less water.
People can become stressed due to higher food costs and
the lack of other things that are normal in their life.
Drought also results in snakes moving closer to water
and food in residential areas resulting in more snake
bites. Less-developed countries have more difficulties
with water shortages because they do not have the same
helpful equipment as more-developed countries. Sometimes
they have to move because of pollution or lack of water.
War can even break out because people or countries could
begin fighting over food and water.
|
History of drought
Drought is a normal part of the cycle of the climate in most
parts of the world. It is written about in the Epic of
Gilgamesh and the Biblical story of Joseph. Historians
believe that people migrated out of Chile and Africa
thousands of years ago because of drought.
Well-known historical droughts include: |
- 1900: a drought in India that killed
between 250,000 and 3.25 million.
- 1921-22: a drought in the Soviet
Union in which over 5 million died from starvation
- 1928-30: a drought in Northwest
China resulting in over 3 million deaths by famine.
- 1936 and 1941: droughts Sichuan
Province China resulting in 5 million and 2.5 million
deaths respectively.
- The 1997-2009 Millennium Drought in
Australia led to a water supply crisis across much of
the country. As a result, many desalination plants were
built for the first time.
- In 2006, Sichuan Province, China,
experienced its worst drought in modern times with
nearly 8 million people and over 7 million cattle facing
water shortages.
- A 12-year drought that was
devastating southwest Western Australia, southeast South
Australia, Victoria, and northern Tasmania was "very
severe and without historical precedent".
- In 2005, the Amazon basin
experienced its worst drought in 100 years.
- Recurring droughts in East Africa
have caused desert areas to grow. This is called
desertification.
- In 2012, a severe drought struck the
western Sahel. 10 million people were at risk of famine
and almost $1 billion was sent to help.
|
 |
| President Barack
Obama discussing the drought in California with
farmers, 2014. |
Protection, mitigation and
relief
Farmers can lessen the effects of (mitigate) drought by
properly watering and rotating their crops. Agencies have
been formed to focus on soil preservation. This began in
1935 after President Roosevelt signed documents creating the
Soil Conservation Service. The name has since been changed
to the Natural Resources Conservation Service.
Here is a list of ways that we can protect against drought,
lessen the effects of drought, and bring relief to those who
are affected by drought: |
- Cloud seeding: This is a form of
purposely changing the weather to bring rainfall. This
remains a hotly debated topic and there is not yet
scientific proof that it would work.
- Dams: Many dams and their associated
reservoirs supply additional water in times of drought.
- Desalination: Removing salt from
seawater could make more fresh water available for
watering plants and drinking.
- Drought Monitoring: If we can
closely watch and measure rainfall levels and compare
them with current water usage, it could help prevent
man-made drought.
- 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 home maintenance can help prevent drought. In
drier climates, it is popular to Xeriscape yards.
Planning the landscaping in a way that requires little
or no watering is a good way to preserve water.
- Rainwater harvesting: We can collect
and store water that is already given to us naturally.
Rainwater from roofs or other surfaces can be used when
we would normally use a hose.
- Recycled water: Former wastewater
(sewage) that has been treated and purified can be
reused.
- Transvasement: We can build canals
or redirect rivers toward drought-prone areas.
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Quick facts about drought |
- Drought is a time when the land is
too dry.
- Drought can be caused by nature or
by man.
- When areas do not get enough rain,
drought happens.
- Weather patterns can bring about
drought.
- Erosion of soil can cause drought.
- Humans can bring about drought by
deforestation or using too much water.
- Drought can have serious
consequences: It can be bad for the environment and
living things in certain areas, it can cause changes in
the economy of an area or country, and it can affect the
health of people.
- There are many ways that people can
help prevent drought and help areas that are naturally
prone to drought.
|
 Kiddle: Drought
Wikipedia: Drought |
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