Megacities A megacity is generally defined as a metropolitan area with a total population in excess of 10 million people metropolitan area population

In 1800 only 3% of the world's population lived in cities.world's population By the end of the 20th century 47% lived in cities. In 1950, there were 83 cities with populations exceeding one million; By 2007, this had risen to 468 agglomerations of more than one million.[2]agglomerations[2] If the trend continues, the world's urban population will double every 38 years, say researchers.urban population The UN forecasts that today's urban population of 3.2 billion will rise to nearly 5 billion by 2030, when three out of five people will live in cities

Spatial Pattern

The increase will be most dramatic in the poorest and least-urbanised continents, Asia and Africa. AsiaAfrica One billion people, one-sixth of the world's population, now live in shanty townsshanty towns

Cities with over 1 Million

The concentration of the world’s population in urban areas is growing at a rapid rate Megacities, currently defined by the United Nations (UN) as cities of over 10 million people1 from 1975 to 2015, the number of megacities will have grown from five -- three of them in the developing world -- to all but four in the developing world (UN, 1998).1

Some of the problems of megacities include: Explosive population growth. Alarming increases in poverty Massive infrastructure problems with telecommunications services, transportation and congestion. For example, traffic congestion in Bangkok is so bad that the average commute now takes three hours Pressures on land and housing Environmental concerns, such as contaminated water, air pollution, and overdrawn aquifers. For instance, Mexico City’s aquifer is being overdrawn and is sinking by about 1 meter per year Disease, high death rates, drug-resistant strains of infection, and lethal environmental conditions. For example, 12.6 percent of the deaths in Jakarta are related to air pollution causes Capital scarcity Dependence on federal or state governments for funding

Reasons for growth of megacities High population growth rates – high fertility rates Rural-Urban Migration –

Mexico City, Mexico Urban agglomeration in 1990 was 20.2 million, and is estimated to reach 25.6 million by the year This growth represents an annual rate of change of 2.4% for the decade. A defining aspect of Mexico's population is its youth; in 1980, 48.9% of the total population was in the 0-19 age group. Another important figure is the 40% of the total population that live in "informal settlements." Average life expectancy in Mexico City is 66 years for males and 72 years for females. Pollution may be Mexico City's most serious problem one quarter of the more than 10,000 tons of solid waste generated daily is dumped illegally or remains in the streets infant mortality rate in poor areas is up to three times as high as that in the rest of the city.

Asia's largest slum, Dharavi, lies on prime property right in the middle of India's financial capital, Mumbai (Bombay). It is home to more than a million people. Many are second-generation residents, whose parents moved in years ago. Today's Dharavi bears no resemblance to the fishing village it once was. A city within a city, it is one unending stretch of narrow dirty lanes, open sewers and cramped huts.

More than half of the world's population will live in cities by 2008, most of them in developing countries, says a report by the UN Population Fund… while the megacities will continue to grow, the majority of the population growth will be in urban areas of 500,000 people or fewer. Without adequate planning, urban growth will create huge slums, degrade the environment and radicalise the young. There are currently one billion slum dwellers

Why the cities have grown? Rural urban migration - In China, 125 million people have moved from areas of low agricultural productivity to coastal cities - that's 25% of the workforce, and you've got another 25% waiting to move