population density and distribution
TRANSCRIPT
I.B. Geography – syllabus details:
http://www.cis.edu.hk/Sec/ss/Geography/IB/IBSYLLABUS.doc
Population density and distribution
http://www.flickr.com/photos/arenamontanus/375127836/
CONTENT:2.1 Population distribution and density at global
and local scales• Factors influencing population distributions
OUTCOME:• Appreciate the broad, global distribution of
population• analyse the distribution in more detail at a
country level. • Describe and quantify the spatial variations in a
chosen country • Explain the variations in terms of environmental,
economic, historical, cultural and political factors.
www.maps.com/ref_map.aspx?pid=12880
75% people live within 1000 km of sea
85% live in areas less than 500m high
85% live between latitudes 68o North and 20o North
<10% live in S. hemisphere
There are over 6 billion people in the world today.
Distribution is very uneven – there are a number of different reasons for this (more on these reasons later!)
Asia and Europe have the highest densities of population.
World’s population varies latitudinally – 80% lives between 20 and 60 degrees north of the equator.Primary concentrations >100 per sq km - SE Asia, Europe + NE USA.Secondary concentrations 25-100 per sq km – California, coastal Brazil, Nile Valley.Areas of low population density 2-25 per sq km – Norway, New Zealand, Canada, North Africa, S Argentina, Australia.
64% of the world’s land area has <2 people per sq km. 35-40 of this land area is regarded as unihabitable.
Areas with environmental advantages tend to be densely populated while those with disadvantages tend to be sparsely populated with social and economic deficiencies. There are exceptions to this - eg Bangladesh.
Population density = number of people per sq km. Usually shown by a choropleth mapDensities are grouped into classes and coloured lighter or darker to show lesser or greater density,Maps are easy to read but:•hide concentrations •suggest abrupt changes at country boundaries
Key to explaining distribution is the ability to feed a population.The world’s 6 billion people are not distributed evenly across the Earth’s surface.Almost all of the world’s inhabitants live on 10% of the land area75% live within 1000 km of the sea90% lives north of the equator where the larges proportion of the total land mass is located (63%)85% lie in areas < 500m high85% live between latitudes 68o N and 20o N< 10% live in the southern hemisphere.Most live in temperate low lying areas with fertile soils
pg 122
How will the World’s population be distributed in the future? By 2030 the population of E and S Asia will be over 4.1 billion people, about 1.8 billion more than now.They will comprise 44% of the world’s population on 13% land areaAreas of the Earth that are not presently inhabited will remain uninhabitedWithin the inhabited areas there will be a core – periphery polarisationRapid urban pop growth will continue in LEDCs
Recap…
1.Describe the differences between population density and population distribution.
2.Describe the world pattern of population distribution.
Factor How would this contribute to a sparsely populated area (egs)
How would this contribute to a densely populated area (egs)
Physical
Climate
Resources
Historical
Cultural
Political
Economic
Homework question….
Explain why the distribution of the world is uneven.
Describe and quantify the spatial variations in a chosen country and explain the variations in terms of environmental, economic, historical, cultural and political factors
See Waugh pg 347
Key points:• Over 90% of Brazilians live in a discontinuous strip about 500km wide
adjacent to the east coast• This accounts for <25% of the country’s total land area• Density declines rapidly towards NW • NE – dry, long and frequent drought, high temps and poor soils make th
area unsuitable for growing high yield crops or rearing animals• Sertao also lacks known mineral or energy reserves, communications are
poor and basic services of health, education, clean water and electricity are lacking. Birth rates are high
• There is a rapid migration to urban areas, high infant mortality rate and short life expectancy
• Tropical rainforest climate is hot, wet and humid, rivers flood annually and there is a high incidence of disease
• Forest is difficult to clear, soils are rapidly leached and become infertile.• Communications are difficult to build and maintain• Area has suffered from lack of investment. Supports subsistence
economies.
anomalies
Two anomalies – Manaus. Had two growth periods:
Rubber boom at the turn of the 19th 20th centuries while the second began in the 1980’s with the development of tourism and the granting of its new status as a freeport.
Carajas and Trombetas – mineral exploitation
Tucuri – hydro-electricity
Moderately populated areas
• Easterly parts of the Brazilian Plateau. Climate is cooler and it is healthier than on the coast and rainforest
• Soil is a rich terra rossa ideal for growing coffee.• Several mineral resources have been found• Rainfall is irregular with a long winter drought• Communications are still limited• Federal investment has been insufficient to
stimulate much population growth
Highest population densities
• Eastern parts of the plateau around Sao Paulo and Belo Horizonte and east coast have the highest population densities
• Coastal area is often hot and humid• Water supply is good• Several natural harbours proved ideal for ports – trade
and industry• Salvador, first capital was centre of slave trade• Rio became second capital developing as an economic,
cultural and administrative centre. It has received increasing numbers of tourists from overseas and migrants from the north of Brazil
Sao Paulo
Sao Paulo is one of the fastest growing cities in the world
Cooler climate and terra rossa soils led to growth of commercial coffee farmiing
Access to minerals such as iron ore and energy supplies made it an industrial centre
It has received high levels of investment leading to development of communications network and modern services.
New growth poles
• Around Belem, based on discovery and exploitation of vast deposits of iron ore and bauxite, construction of HEP and the advantage of access along the coastal strip and Amazon corridor
• Brasilia, built in the early 1960’s to try to redress the imbalance in population density and wealth between the south east of the country and the interior.
Describe the global distribution of population. You should include these terms in your answer: sparsely populated, densely populated
Factor How would this cause a sparsely populated area (examples)
How would this cause a sparsely populated area (examples)
Physical
Climate
Resources
Historical
Cultural
Political
Economic
Using only an annotated map, explain how physical, historical, cultural and political factors have affected the distribution of a country of your choice.