Droughts
Group J - Amaia, Angela and Harry
Explain the characteristics and spatial distribution of droughts using at least two specific examples. [10 marks]
Droughts occur when there is a lack of or an absence of rainfall in the country. This lack of rainfall and increase in temperature is also able to dry up small lakes and streams that may be a source of drinking water for the people. Water is one of the(if not the most) important resources we have.
The main problems that droughts cause are famine, bio-diversity loss, conflict about the distribution of water in the drought area, refugees, desertification, economic loss, dependency, health problems increase, and education of the children suffer. Droughts can technically happen anywhere in the world, however the most severe cases of droughts are found in Australia, Brazil, the Sahel, China and India. There are also classifications, it can be classified as an economic water scarcity, which is when there is water however it cannot be obtained because of a lack in funds. And there is physical water scarcity wherein the water is simply non existent.
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Droughts are caused by Human causes or physical causes. Human
causes include deforestation, overpopulation, industrial, agricultural demand,
and economic development. More population and development have increased the
demand of water resources while significantly reducing the water availability
through deforestation. Physical cause is global trend of rising temperature,
which result in requiring more amount of water in growing crops. Despite this
trend, annual rainfall is decreasing.
For the spatial distribution of
droughts, this hazard can technically happen anywhere in the world. However the
most severe cases of droughts are found in Australia, Brazil, the Sahel, China
and India. The causes of droughts can be both human induced or environmentally
induced. For instance, droughts in 2011 along Tangtze Riger in China was
one of the most serious problem of the country. The cities that are located
along river suffered as 50% of the lands for crops were affected by droughts.
In addition, more than 4.23 million people had difficulty in finding adequate
drinking supplies.
First characteristic is magnitude. Magnitude is defined
as the measurement of the strength of a hazard.
Figure 1. a tabulated data that show the major natural hazard and
deaths they caused from 1980 to 2000
According Figure 1, the magnitude of the drought is the
highest among the other disasters. The consequences of droughts are very severe
that people must be aware and alarmed when drought occurs. Compared to other
types of disasters (storms, floods, earthquakes, volcanoes) in the figure 1,
drought caused the largest death. Drought can trigger economy decay,
malnutrition, food shortages, and can potentially kill people. For example, in
Africa, in the year of 2011, 10 to 11 million people suffered under drought and
needed emergency food aid. In specific, 25 percent of Kenyans suffered from
acute malnutrition, including more than 37 percent of those living in the Lake
Turkana. In addition, 100,000 people have died due to the drought and half of
them were children under 5. With high magnitude, droughts usually result in
severe consequences that hamper human lives.
Second characteristic is that droughts are predictable hazards. Palmer drought severity index (PDSI) can
predict the areas with commonly prolonged droughts. PDSI measures the supply
and demand of water of the area. The government and NGOs refer to PDSI in order
to be prepared.
Figure
2. A map of the United States with PDSI in 2007
According to figure 2, extreme drought
occurred at the Western central, Southeastern regions of the country. The
government of the U.S. can refer back to the map with PDSI in the past.
Therefore, they can alleviate the severity of consequences of droughts in the
areas. Using PDSI, droughts are the predictable hazards.
The
last characteristic is frequency. It is defined as the return interval of
hazards.
The Sahel region of Africa suffers from drought on a regular basis since the 1980's. They only experience two seasons which are wet and dry and if the rains "fail" they experience drought. The hazard has brought multiple problems to the region. The land not only suffers from the hazard but from other human induced problems such as overgrazing and over cultivation which dilutes the soil and leads to deseritfication. This brought about multiple socio-economic problems such as crop failure, soil erosion, famine and hunger. Crop failure happens because soil erosion, the soil lacks the nutrients it gets from water to grow the crops. This causes families and the region to lose income. The crop failure also brings a food shortage which leads to hunger and eventually the death of thousands.
Sources:
http://www.bbc.co.uk/schools/gcsebitesize/geography/water_rivers/drought_rev3.shtml
http://greenfieldgeography.wikispaces.com/Characteristics
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