1. Population distribution & density Flashcards
Population distribution refers to
the way in which people are spread over an area
population is unevenly distributed because
some areas of the world are densely, and others sparsely settled
the different scales population distribution can be examined at
global, regional and local level.
the fundamental questions are where they are located and why there.
both human and physical factors explain population distribution but, in general, physical factors have a
greater influence in the less developed countries
the physical factors that explain population distribution (7)
1) climate vegetation
2) Communications
3) Diseases
4) Economic and political factors
5) Relief
6) Soils
7) The availability of portable water
population distribution is the
spread of people within an area, whether that area is a village, parish, county, continent or globe
explain figure 1.1 world population distribution using a dot map
each dot on the map represents 100 000 people, populations are dispersed/widely scattered and clustered/concentrated in others
check notebook #7
in general the map of world population distribution shows that (3)
1) most of the people live north of the equator which has a larger land area than the south, and within this area there is a marked concentration between 20° and 60° North.
2) the margins of continents have attracted the greatest concentrations.
Four clusters are apparent - East Asia (including China and Japan), South Asia (including India, Pakistan and Bangladesh) Europe and North Eastern United States of America and Canada.
3) The Arctic North, the dry interior of Australia and the African Sahara have attracted relatively few people.
factors affecting population distribution (6)
1) Cultural traditions
2) Historical factors
3) Human/economic factors
4) Physical factors
5) Political instability,
6) Religious beliefs
physical factors affecting population distribution generally refer to
natural or environmental influences.
modern technology can overcome many of the physical limits and has allowed settlement to spread over the earth
what can overcome many of the physical limits and has allowed settlement to spread over the earth
technology
how climate affects population distribution
climate affects the population distribution globally.
areas of extreme cold such as the artic and Antarctic, and
extreme aridity such as the Sahara Desert remain very sparsely populated.
people tend to seek out climates that are not extreme therefore temperate and tropical moist climates such as Northwest Europe and Asia tend to support the greatest clustering of population
the tropical climates that support the greatest clustering of population are
Northwest Europe and Asia
how soil affects population distribution
fertile soils for the cultivation of food have always attracted human settlements.
River Valleys in the past (The Nile and Tigris-Euphrates) as well as in the present have attracted large populations because of soils that are enriched by the rivers, access to potable water and food.
The Valleys of the large Asian Rivers such as the Ganges and Hwang Ho are some of the closely settled areas of the world.
some of the closely settled areas of the world that are rivers are
The Valleys of the large Asian Rivers such as the Ganges and Hwang Ho
why do river valleys attract large populations
because of soils that are enriched by the rivers, access to potable water and food
how relief affects population distribution
Low lying areas attract large populations.
Highlands are less favored because of their rugged nature, low temperatures, thin soils, steep slopes and short growing seasons.
why Highlands are less favored for populations (5)
because of their
1) rugged nature
2) low temperatures
3) thin soils
4) steep slopes
5) short growing seasons.
how natural resources affects population distribution
some areas are either poor in natural resources or lack the capital to develop them therefore they cannot support large populations.
- the large population of western Europe was sustained by the discovery of coal.
- the opening of the northern frontier in Mexico was given impetus by the silver deposits at Zacatecas.
- Mining settlements were also established in the Andes to exploit silver deposits.
However, population numbers in mining areas tend to decline as deposits become expensive to mine or the mineral becomes depleted
when do population numbers in mining areas tend to decline
when deposits become expensive to mine or the mineral becomes depleted
Human/Economic factors affecting population distribution
- Economic factors such as economic consideration
- Government policy/government influence
- Communication
how economic factors affects population distribution
Economic considerations remain one of the most important factors in determining population distribution.
Good infrastructure (roads, water, electricity) attract populations.
Transportation costs make it difficult to exploit the resources found in the interior of South America.
In general terms, the longer the journey into the interior; the greater the transportation costs and the less profitable economic operations in these parts are likely to be.
Population distribution therefore remains low in the interior of South America.
why population distribution remains low in the interior of South America.
Transportation costs make it difficult to exploit the resources found in the interior of South America because the longer the journey into the interior; the greater the transportation costs and the less profitable economic operations in these parts are likely to be.
Population distribution therefore remains low in the interior of South America.
what is the most important factors in determining population distribution
Economic considerations
how government policy affects population distribution
The State may directly or indirectly decide to encourage development in a particular area or region
In modern times, governments have taken a regional view of resource development and created urban centers to act as economic nodes.
To encourage such developments they offer incentives, tax breaks and employment contracts to investors who are willing to go into these areas. Areas which receive high levels of investment are likely to attract large populations.
example of when governments have taken a regional view of resource development and created urban centers to act as economic nodes
the Venezuelan government established the complex of towns that make up Cuidad Guayana on the Orinoco
River to smelt bauxite and iron ore brought in from the Guiana Highlands to the south of the river.
This development has also been influenced by the presence of a transportation route provided by the river.
example of a area which received high levels of investment from the government that attracted large populations.
Brasilia, the capital of Brazil, is an excellent example. The capital was transferred from Rio de Janeiro to
a site that was nearer to the centre of the country to redistribute the population. It became the seat of government and headquarters of major Brazilian companies. Population growth was explosive.
Planned for a half a million people, the city is now home to 2 million.
how communications affects population distribution
Caribbean capitals developed because of their port functions, links between the colonies and Britain.
Modern modes of transportation and communication have allowed population distribution to spread over most continents.
Most places are easily accessible over land allowing individual choice in residence depending on personal preference.
Some people are moving into previously sparsely settled areas because of highway construction,
why Caribbean capitals developed
Caribbean capitals developed because of their port functions, links between the colonies and Britain.
example of where people are moving into previously sparsely settled areas because of highway construction
New highways in Caribbean counties such as
- H1ghway 2000 in Jamaica and the
- Adams-Barrow-Cummins Highway in Barbados are changing the distribution of population.
Dot maps usually display
counts with each dot representing a specific value
Dot maps are
Thematic maps that use points/dots to represent a phenomenon, such as a population to depict variation in density in a given area
dot maps allow the reader to
identify areas with higher or lower concentrations of people.
In areas with a higher population frequency, the dots in dot maps are
more numerous and appear closer together
in areas with a sparser distribution, the dots in dot maps are
are more widely spread
how dot maps are effective
It is visually ve1y effective in identifying and locating variations in population distribution.
Steps in the construction of dot maps showing population distribution
Figure 1.2 Dot map of Barbados showing population distribution
1) Create a base map of Barbados showing the boundaries of the parishes in pencil.
2) Decide on the graphical size of the dot.
Bear in mind the maximum and minimum number to be shown and the size of the map.
A stencil could be used to ensure that the dots are of equal size.
3) Careful consideration must be given to the value of the dot.
The largest population shown in the table is 83,684 and the lowest 5,254.
A dot value of 2,000 may be chosen although it will distort the population distribution of the smaller parishes.
4) Calculate the number of dots needed for each parish and insert them in the appropriate parish on the map.
5) Consult topographical maps and other information to assist with the placing of the dots in the appropriate places in the parish.
Advantages of Dot Maps (4)
- It is intuitive in associating the number of dots with number of people
- It has a strong visual impact.
- It can recover original data from the map by counting dots
- Manual placement of dots takes into account the distribution of other phenomena, such as agricultural land use, mountainous terrain.
Disadvantages of a Dot Map (3)
- Dots may be interpreted as representing a single instance of the phenomena at a particular location
- If dots form too dense a pattern - visual overlap - it is impossible to recover original data values
- poor choice of dot size can distort the accuracy of the map. Too small a dot value may cre1te clustering, while too large a dot value may result in blank spaces appearing unpopulated. It is difficult to count large numbers of dots
Human placement is subjective resulting in
different distributions for same data
Describe the population distribution shown on Figure 1.2
The population of Barbados is very unevenly distributed.
Most people are concentrated in the south west of the island, with very few in the east and north.
The central area shows a moderate population spread.
Explain the factors influencing the population distribution of Barbados shown on Figure 1.2
The main factors accounting for the distribution of population in Barbados are the relief and socioeconomic factors.
The southwest of the island is the location of the capital, Bridgetown, and is the main port. It also has the greatest concentration of commercial and business activity which has attracted many persons seeking jobs.
Along the south and west coasts intense tourism activity has attracted many people.
To the east, the very rugged Scotland District is prone to landslides and has very few economic opportunities and, therefore, does not support many people.
In the central area some land is still used for agriculture, although there are many recent housing developments
The Lorenz curve is a graph which
represents inequality
The Lorenz curve may be used to show
inequality in the distribution of population, income, food, medical care and many other assets
how is population distribution plotted on a Lorenz curve
When representing population distribution,
population, shown on the x-axis, is plotted against area on the y.
Both are plotted from O to 100%
in a Lorenz curve the population is plotted on what axis?
the x axis
in a Lorenz curve the area in population distribution is plotted on what axis?
the y axis
what would happen if the population were evenly distributed
20% of the population would inhabit 20% of the area;
75% of the population would inhabit 75% of the area.
The relationship would be linear and the result would be a straight line.
However, this rarely occurs as it has been shown that some areas are more attractive to settlement than others.
The Lorenz curve commonly shows this unevenness.
The greater the distance of the curve from the diagonal line, the greater the inequality in distribution.
in a Lorenz curve when plotting population distribution the relationship is rarely linear with a straight line because
some areas are more attractive to settlement than others.
in the Lorenz Curve, what shows the greater the inequality in distribution.
The greater the distance of the curve from the diagonal line, the greater the inequality in distribution.
Steps in the construction of Lorenz curve
1 Calculate the percentage population and percentage area for each parish.
2 Order the parishes by decreasing size of population
3 Set up axes of a graph for values 1-100 per cent, with the x-axis showing the cumulat1ve percentage of the population and the y, the cumulative percentage of the area (columns 2 and 4 above.)
4 Plot each variable according to its cumulative percentage populat10n (x) and cumulative percentage area (y).
5 Join the points plotted to form a smooth curve .
The line x=y which indicates an even d1stnbution between area and population may be indicated
construct the Lorenz curve for Barbados
chegg
Advantages of the Lorenz curve for displaying population inequality
it provides a visual representation of inequality of population distribution.
It is sufficiently simple that it can be compared across countries and be easily interpreted.
scale independence: it does not consider the size of the country, the way it is measured, or whether it is a dense or sparely settled.
Population independence: it does not matter how large the population of the country is.
The important principles that satisfies the Lorenz curve
scale independence:
it does not consider the size of the country, the way it is measured, or whether it is a dense or sparely settled.
Population independence:
it does not matter how large the population of the country is.
Disadvantages of the Lorenz curve
The Lorenz curve may not give an accurate picture of actual inequalities if the resources of the area are unevenly distributed.
Populations of similar size may have dissimilar shaped curves
It can only be analyzed in terms of cumulative percentages
The measure will give different results when applied to different levels of data, for example, constituencies instead of parishes.
As for all statistics, there may be systematic and random errors in the data.
which areas generally tend to attract larger populations.
Generally, areas where climatic conditions are not extreme and with abundant natural resources tend to attract larger populations
what is often used to illustrate population distribution.
Dot maps and the Lorenz curve
Using clot maps and the Lorenz curve to depict population distribution result in
a graphical representation of population over an area.
However, these techniques may lead to an over-simplification of reality
The study of population distribution remains critical to an understanding of
the reasons why people locate the way they do
While many distribution patterns may have had their genesis in historical factors, what also plays an important role?
contemporary forces are also playing an important role
Being able to identify areas of largest population numbers can allow policy-makers to
plan more effectively and more strategically.
In a world of scarce resources, this is essential to ensure that optimal use of the resources is always the over-riding consideration.
The Lorenz curve is useful for investigating population distribution because it shows the relationship between:
cumulative area and population
Economic considerations remain some of the most important factors in determining population distribution.
These considerations are often viewed in terms of:
costs,
revenue, and/or
profits/wages
