Greater São Paulo, a city of 21 million people, is experiencing its worst drought since the 1870s; the city’s water supply is in danger. Sewage, pesticide, and trash pollute São Paulo’s rivers and reservoirs. Rain falling on the vast paved surface of the metropolis drains quickly into its polluted rivers. Brazil’s ample natural resources include 13 percent of the global supply of freshwater for only 3 percent of the world’s population. Yet as of August 25 South America’s largest city had only enough water in its reservoirs to supply its residents for ninety-three days.
Many of the world’s other thirty-six megacities, each with more than 10 million inhabitants, also struggle with limited local water supplies. As recently as 1950, New York was the only city of this size. Half of today’s giant cities face mounting difficulties in securing and managing water resources for their growing populations. As in ancient times, water supply is emerging as a challenge to civilizations both rich and poor.
The Fabric of Space, by Matthew Gandy, contains six loosely connected essays with much on historic and current water problems in Paris, Berlin, Lagos, Mumbai, Los Angeles, and London. A geographer at University College London, Gandy blames the lack of water on “a mix of technical disagreements, political expediency, administrative inertia, and economic uncertainty [that] produces a common pattern of extended delay” in taking action. He warns that the accelerated rate of climate change “could overwhelm the capacity of many cities to respond” to environmental crises. This is what may well be happening in giant urban agglomerations such as Los Angeles, São Paulo, Mexico City, Mumbai, and Beijing, all of which consume water wastefully while neglecting the need for long-term supplies.
Most conspicuously in danger are the growing number of supergiant cities, with populations of at least 20 million. They are heavily concentrated in poor countries that lack the wealth and institutional strength to manage droughts, floods, and other water emergencies on this scale. Among these supergiants are Delhi (25 million), Shanghai (23 million), Mexico City, São Paulo, and Mumbai (21 million each), and Beijing (20 million). United Nations demographers expect that by 2030 Delhi’s population will rise to 36 million and that Tokyo will remain the world’s most populous city with 37 million. According to A.K. Biswas of the Third World Center for Water Management in Singapore:
From Istanbul to Johannesburg, and Jakarta to Mexico City, there are simply no new sources of water that could be harnessed economically and in a socially and environmentally acceptable manner which can quench the continually increasing urban-industrial thirst.
The growth of megacities is just one part of global urbanization. According to the United Nations, while the number of megacities has nearly tripled since 1990, the number of cities…
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