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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

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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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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