Population rrmtt.wikispaces.com rrmtt@yahoo.com Geography Unit One Population rrmtt.wikispaces.com rrmtt@yahoo.com

Population The world population is the population of humans on the planet Earth. It is currently estimated to be 6,868,400,000 by the United States Census Bureau.

Population Distribution Describes the way in which people are spread out across the Earth’s surface. Population distribution means the pattern of where people live. World population distribution is uneven. Places which are sparsely populated contain few people. Places which are densely populated contain many people. Sparsely populated places tend to be difficult places to live. These are usually places with hostile environments e.g. Antarctica. Places which are densely populated are habitable environments e.g. Europe.

Population Distribution Population distribution can be shown by means of a DOT MAP.

Dot Maps Used to represent themes that vary smoothly over space but are discrete, dot maps create a visual impression of density by placing a dot or some other symbol in the approximate location of one or more instances of the variable being mapped.

Dot Maps Dot maps should be used only for raw data. Appropriate themes for dot maps include livestock farms, utility poles, and population distribution in a region.

Dot Maps When constructing a dot map, two parameters must be considered: the graphical size of each dot and the value associated with each dot.

Dot Map - Example For example, you might stipulate that each dot be 2 pixels in diameter, and each represent 100 persons. In general, many small dots, each representing relatively few instances of the attribute, is more effective than a few large dots, but is more tedious to construct.

Dot Maps The advantages include: strong visual representation original data can be recovered if mapped correctly and used for other purposes dot maps can be very easy to read

Dot Maps Disadvantages include: tedious to contrast by hand computers usually assign dots randomly proper dot value has to be determined can give the misconception that some areas are not populated topography of the area should be known

Population Density Describes the number of people living in a given area, usually a square kilometre. It is an average number. Population density is calculated by dividing the number of people by area. Population density is usually shown as the number of people per square kilometer. The map below is a choropleth (shading) map and illustrates population density. The darker the colour the greater the population density.

Population Density Represented by means of a choropleth map.

Choropleth Maps These maps, where each spatial unit is filled with a uniform colour or pattern, are appropriate for data that have been scaled or normalized in some way. For example, density information, expressed as "per unit area," is appropriately represented using a choropleth map.

Choropleth Maps Choropleth maps are also appropriate for indicating differences in kind of an area data, like ownership or use of land or type of forest cover.

Choropleth Maps The advantages of such a map include: strong visual representation relatively easy to construct

Choropleth Maps Disadvantages include: these maps can hide concentrations of population within each unit area gives the impression that population is evenly distribute din some areas it suggest that is are abrupt changes in population density at boundary lines a poorly designed system of colouring or shading can make quite small spatial differences seem large, or huge difference look smaller

World Density Population The map above shows that world population distribution is uneven. Some areas have a high population density while others have a low population density. Areas of high population density tend to be located between 20° and 60°N. This area contains a large land area and a relatively temperate climate.

Factors affecting Population Density There are a range of human and natural factors that affect population density.

Other Factors Vegetation Water supplies Diseases and pests Soils Communications

Dot map - Exercise