3.5A - Rural-Urban Migration and Megacities
Rural-urban migration (push and pull factors), and/or natural increase, is responsible for the growth of megacities (Mumbai or Karachi); rapid urban growth creates social and environmental challenges.
Migration is a permanent move from one place to a new place, for one year or more.
Rural-urban migration means people moving from the countryside to cities.
A megacity is a city with a population of over 10 million.
Rural-urban migration feeds the growth of the world's megacities. In developing and emerging countries abuot 60% of urban growth is caused by rural-urban migration and 40% by high birth rates in cities (internal growth or natural increase). China has seen 150 million internal rural-urban migrants since the Open Door Policy leading to the creation of 7 megacities.
Developing world cities like Lagos and Karachi have very high growth.
- Lagos had 1.4 million inhabitants in 1970, but now has about 21 million.
- Karachi had 400,000 in 1947, 9 million in 1998 and now has almost 15 million.
- Population growth due to rural-urban migration from the poor provinces of Punjab and Sindh.
This creates social challenges:
- Housing is in short supply, leading to the growth of slums and shanty towns that lack water, sewers and power supplies.
- Poverty is rife, because wages are low and jobs are in short supply; many people have dangerous informal jobs.
- Lack of taxes means that the city governments struggle to supply essential health and education services.
- Lack of water and sanitation means disease and illness are common in slums.
And environmental challenges:
- Sprawling slums at the city edge cause deforestation and loss of farmland and increases flood risk.
- Wood fires, old vehicles and industry means that air pollution levels are high.
- Rivers and lakes are polluted with sewage and industrial waste, making health problems worse.
- Critical resources, especially water, are in short supply because of souring demand.
