字幕列表 影片播放 列印英文字幕 Population distribution refers to how populations is distributed unevenly around the globe. Because of this varied distribution, different regions and countries have different population densities. Population density measures the average number of people per square kilometer. The population density in a given country can be calculated by dividing the population by the area of that country. For example is on 2014 Thailand had a population of 68.7 million people spread over 513000 square kilometers. When you divide 68.7 million by 513 thousand square kilometers you get a population density of one hundred and thirty three point eight people per square kilometer. Patterns of population density can be displayed on a map such as a choropleth map or a dot distribution map. For example this current plate map shows the population density on a global scale. You can see that for places with high population densities are mainly found in the northern hemisphere. As mentioned earlier, some regions are densely populated, while other regions are sparsely populated. For example, in Sichuan Province China, the Sichuan Basin in the east is said to be densely populated. The mountainous western regions of the province is sparsely populated. Factors that encourage high population densities include the following. Regions of low elevation tend to have milder climates which attracts the people. Regions low-lying fertile land are good for agriculture. For example the North China Plain which lies flood plains of the Yangtze and Yellow Rivers. Regions with a good supply of natural resources are rich in resources such as copper and fossil fuels. Coastal areas tend to have a higher population than inland areas. For instance the vast majority of Australians live with 100 kilometers of the coastline. There several reasons for this. Coastal areas have a much milder climate than inland areas. They have rich resources such as fisheries. Coastal areas were also for those areas reached by immigrants, when new countries like Australia, New Zealand and the Americas were first settled. Factors that tend to result in sparse population densities include regions with extreme climates. For example extremely hot dry regions such as the deserts of Western Australia or cold regions such as the polar regions. Regions with high elevation such as the Qinghai-Tibetan plateau. At high altitudes temperatures tend to be cooler and soils are thinner and less fertile. The rugged relief these regions also makes development very difficult. In addition to extreme climates, regions in the interior of continents also tend to have poor access. Regions with dense impenetrable jungles are also sparsely populated.