Mega-cities
Reductions in CO2 emissions, support for developing nations which are having to deal with the results of climate change and the protection of forests. These are the issues up for discussion by the nearly 200 countries involved in the climate summit about to begin in Cancun in Mexico.
This new round of negotiations has to produce concrete agreements to replace the Kyoto Protocol which expires in 2012. By turning the spotlight on four mega-cities – Beijing, Mexico City, Cairo and Nairobi – Radio Netherlands Worldwide is taking a look at the most important environmental issues: air pollution, safe drinking water, overpopulation and the depopulation of the countryside.
Two cities - Two Examples
Manila – Philippines
Manila’s main problem is wastage of clean drinking water. Since the mid-1990s around 60 percent of the purified drinking water seeps into the ground from the leaky old network of pipes. Two private drinking water companies have divided Manila into a western and an eastern part. The pipelines in west-Manila in particular need replacement. The situation in the eastern part of the city has improved substantially as a result of heavy investment. Now only 14 percent of water is lost.
However, the problems are not over. There was a severe water shortage this year due to lack of rain. The water level in the Angat Dam fell to its lowest level ever. The water companies now want to build a desalination plant. But it is much more expensive to process salt water than it is to use fresh water from rivers, because the desalination plants use a lot of energy.
New York - United States of America
New York’s eight million inhabitants depend on an extensive system of aqueducts and tunnels to transport drinking water to the city from almost 500 kilometres away. To prevent pollution in the reservoirs, the city has purchased the surrounding land. The city council spent five million dollars on land this year.
New York also suffers from unnecessary spillage from leaks due to poor maintenance. A large-scale maintenance programme has been started now, but the tunnels turned out to leak so badly that a by-pass had to be built around the worst parts. It cost 1.2 billion dollars. New York does have drinking water, but at a price. The city still has water shortages when it rains too little.
Julio Cesar Cu Camara has worked as a diver in Mexico City's sewers for 28 years. He's one of only two sewage divers in the city - and one of only a handful in the world. His job is to dislodge garbage that flows into the gutters during heavy rains and which can end up jamming the pumps that expel raw sewage from the city. Sometimes he'll find unexpected items like refrigerators or cars and there are even worse surprises, as Cu Camara explains:
World famous smog
Mexico City with its 20 million inhabitants is the largest urban area in the Western Hemisphere. Its size, location in a valley and inconsistent urban planning mean the city faces a number of environmental challenges. While its smog is world famous (see also: Smog gives Beijing a headache), another major problem is water management.
What is now bustling and crowded downtown Mexico City was originally a peaceful island in the middle of five lakes. Much of the sprawling city sits on what was once a lake bed. The pumping of underground water has caused the clay underneath the surface to compact. The water table has now shrunk to the point where water has to be pumped from more than 1,000 metres below the surface.
Unlike many of the world's megacities, storm water and sewage are combined in Mexico – based on outdated technology from the 1940s. Jorge Chang Castro of Mexico City's pumping stations says it's time to invest in separating the two types of waste water.
"A few neighbourhoods here and there have started to separate their water, but it needs to be done on a larger scale. Why? Because we need to use the rain water to recharge the aquifers. Or hell, build a dam!"
Scientist Arsenio Gonzalez points out that the Aztecs who originally populated the island knew perfectly well how to manage the water flow. They developed an urban plan that was in harmony with the lake system. That all changed with the start of the Spanish Conquest in 1521, according to Gonzalez. The Spanish rulers viewed the seasonal flooding as problematic, and in 1607 created an artificial canyon to drain the lakes and to send raw sewage out of the city.
Then other artificial outlets for the city's sewage were created in the 20th century. Meanwhile, plans to recharge the area's aquifers were neglected. So, now in 2010 clean water has to be brought in at ever higher costs, and after dirtying it the water has to be pumped back out of the valley.
Most people working on water issues in Mexico City say citizens need to be more conscientious about their water use - and they must stop throwing garbage into the streets and waterways, a common practice in the city. That’s why sewers are obstructed by refrigerators, and why Cu Camara has to work hard to free the pumps from unorthodox trash.
Lead photograph of Mexico City by Pulpolux, on Flickr. This and all further use subject to CC licence
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