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Social sciences: geography

Grade 7

Natural hazards

Module 1

The difference between natural disasters and natural hazards

  • Natural hazards are geographical events which occur naturally UNDER (earthquakes and volcanoes), ON (floods) or ABOVE (climatic conditions such as droughts and tropical cyclones) the surface of the earth. Things such as droughts, floods, tropical cyclones, volcanic eruptions and volcanoes regularly happen on a small scale throughout the world. However, if one of these natural hazards leads to – a significant loss of human life and/or – damage to property, and/or – environmental damage,it is called a NATURAL DISASTER.
  • Disasters know no boundaries, and can lead to the loss of thousands of human lives in the areas where they occur.

1. Droughts

1.1 The occurrence and cause of droughts

1.1.1 What are droughts?

A drought is a continuous and lengthy period during which there is no or insufficient precipitation. Thus it is associated with a lack of water, but it does not always lead to a disaster. It is the relationship between the community and their environment that will determine whether a drought will develop into a disaster or not. Isolated droughts rarely occur out of the blue. They usually creep up on a community over several years.

1.1.2 Where do droughts occur?

Study figure 1. It is a world map showing the areas where most droughts occur. You will note that certain countries experience more droughts than others, but that the African continent and India suffer the most from serious droughts.

Figure 1

Activity 1:

To study the dry regions of south africa

[lo 2.1]

Figure 2

a) Make an estimation as to what percentage of South Africa experiences rainfall of less than 500 mm per year.

b) Where in South Africa are droughts most likely to occur? Why?

c) Where in South Africa are droughts least likely to occur? Why?

d) Name ways in which a farmer in the Northern Cape can take precautionary steps against future droughts.

1.1.3 What causes droughts?

Water is essential for life on earth. A drought is the result of a lack of water. Many people think that a drought occurs merely because it doesn’t rain. A decrease in rainfall does indeed cause droughts, but this is not the only cause.

Study table 1, which shows how other factors can lead to the disastrous conditions which are associated with droughts.

Table 1:

Thus changes in climate are indeed implicated in droughts, but poor environmental management has a greater influence on the disastrous impact of a drought.

1.2 The effect (consequences) of droughts on the lives of people and their socio-economic activities

During a period of about 10 years approximately 60 million people worldwide are affected by droughts, and this number continues to increase. In the 1990s, in Africa alone, 35 million people were affected by drought. What will the situation be in the future?

Study the following list of consequences of droughts:

  • no crop rotation
  • failed crops
  • famine: less food is produced
  • loss of lives
  • wells dry up as a result of the lowered water table
  • stock are slaughtered on a large scale: meat prices fall
  • hydro-electric plants may stop operating: electricity prices rise
  • unschooled labourers earn less income: poverty
  • water restrictions are imposed
  • industries suffer due to a lack of water
  • vegetation dies and disappears
  • dust bowls develop on bare soil, and air pollution worsens
  • workers lose their jobs and their income: unemployment causes crime
  • increasing population places more strain on the environment and a vicious circle of disasters develops
  • water levels of rivers and dams fall and some dry up completely: fish die
  • a decrease in the gross national product (GNP) of the country
  • desertification of marginal areas
  • people are forced to migrate out of drought-ridden areas: many are unschooled

Questions & Answers

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s.
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I start with an easy one. carbon nanotubes woven into a long filament like a string
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AMJAD
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Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
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In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
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Source:  OpenStax, Geography grade 7. OpenStax CNX. Sep 09, 2009 Download for free at http://cnx.org/content/col11021/1.1
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