With a population of 24 million people, greater Jakarta ranks among the 10 largest cities in the world. As in other megacities of the developing world, traffic jams, messy urban planning and burgeoning squatter areas plague the Indonesian capital. One of its chief problems is the flooding that affects more than two million of its inhabitants, especially during the rainy season, and the floods are mainly a man-made phenomenon.
When it rains in Jakarta, the entire city grinds to a standstill. Passersby huddle under street venders' awnings while young men, bare-chest and barefoot, spring up from nowhere to direct the barely moving lines of cars away from the most rapidly flooding streets.
For 2.5 million inhabitants of Jakarta, floods are a plague during the rainy season. Muharni - a 40-year-old housewife - has to battle against rising water at least once a week.
She says there's nothing she can do about it, except pile up all her possessions on top of tables or chairs and watch the filthy water invade her home. She fears her three children could get ill from dengue fever or diarrhea.
The rainy season is drawing to an end, but it does not mean Muharni's worries are over, because her community, like other coastal neighborhoods, gets flooded not only by rains, but also by the sea's high tides.
The predicted rise in the sea level in the coming years could make things worse. However, Hongjoo Ham, lead infrastructure specialist in the World Bank, says global warming is but a minor aspect of the problem.
"We're predicting a five-centimeter rise by 2025. Jakarta, itself, sinks by, on average, five centimeters per year. Jakarta is sinking for a very straightforward reason: It's because of ground-water extraction," he said. "This type of ground-water extraction drains the aquifer completely and it creates a vacuum. Then the weight of the buildings push it down and it fills the cavity of the aquifer and, therefore, Jakarta sinks."
Sixty percent of Jakartans are not connected to the water grid, so they do not have much choice but to pump underground water for their personal use. Some areas in the capital have already sank more than two meters.
Cipinang Besar's neighborhood has been affected for years.
Rahmat, a local leader, says that, in 2002 a neighbor mother and her baby died during flash floods. But, despite this, leaving the neighborhood would not be an option for him. He needs to live close to his work.
Each year, waves of migrants like Rahmat flock the every-growing metropolis. By 2025, it is expected to include 35 million people - a 50 percent increase from today. Hongjoo says this is a dangerous trend.
"Jakarta's flooding is mostly a man-made phenomenon," he said. "Enormous population strains really affect it because people build lots of buildings, impervious roads… Especially upstream."
Upstream from Jakarta are the beautiful volcanoes of the Puncak Pass, a green and beautiful mountainous area rapidly clogged up by luxury villas built by the Jakarta elite.
Jakarta is stuck between two walls of invading water: the sea, in the north, where the tides nibble the coastal area; and the rains that gush down the mountain slopes into Jakarta's flat lands.
The city was designed to cope with the floods. The Dutch colonists built an intricate web of canals to divert the excess water towards the sea. But those canals are clogged because of a lack of maintenance.
Jakarta just started an ambitious anti-flood program. Its first step is to dredge those canals - a simple measure that could protect up to one million people from the floods.
The Mangga Dua canal will be the first one to be cleaned. But Timo Worm, a Dutch engineer who came here to train Indonesian technicians, acknowledges that this simple anti-flood measure will be difficult to accomplish.
"The situation looks very bad. When we are dredging, around 50 percent is garbage," he said. "You don't see that in Holland, where there is basically mud, sand clay… When we are working, a lot of people watch and they say "Ah! Good job! Good job!". But, on the other hand, they still throw the garbage before and after our boat, they throw it in the water. So it's kind of a mixed feeling!
According to the World Bank, Indonesia needs $5 billion to solve the flood problem. However, Hugo Ham says even that much money would be useless, if it does not meet a strong commitment from the local government.
"Political will, a need for action, and a public that wants to see the government deliver," he said. Those three combinations really create a strong force to do something about the floods.
Ham thinks that with caution, the problem can be solved.
The good news is the rainy season is drawing to an end. For the next six months, Jakarta will remain dry - at least, in the neighborhoods that are not too close to the sea. During this time, most of the canals should be dredged, so the next rains should not be as bad. That is, if the program goes according to plan.