By Sugita Katyal
JAKARTA (Reuters) - It's one of the fastest-growing megacities in Asia. But some doomsters predict large parts of Indonesia's coastal capital could be under water by 2025.
The reason? Unchecked groundwater mining.
"Goundwater extraction is unparalleled for a city of this size," Almud Weitz, regional team leader of the World Bank's water and sanitation programme, said in an interview for Reuters Environment Summit.
"It's like Swiss cheese. People are digging deeper and deeper and so the city is slowly, slowly sinking. That is why tidal floods are occurring in poor areas on the coast."
Jakarta is one of Asia's more densely populated cities, but experts say it has one of the least developed piped water networks, pushing many residents as well as mushrooming megamalls and skyscrapers to increasingly suck out groundwater.
According to some estimates, Jakarta has a water deficit of about 36 million cubic meters (1.28 billion cubic feet) a year and much of the groundwater is contaminated with faecal matter because of leaky septic tanks.
As the city of around 10 million sinks and sea levels rise because of climate change, Jakarta has become more vulnerable to flooding and the threat of severe tidal surges remains grave.
In recent years, Jakarta, a city criss-crossed by 13 rivers and many canals built by its former Dutch rulers, has been devastated by massive flooding triggered by tropical rains and the incursion of sea water.
A study by a Dutch consultant for the World Bank showed that by 2025, the city could be between 40 and 60 centimeters lower than it is now, if nothing is done to check the crisis.
"An ever-growing population, densely populated residential areas, rapid infrastructural development, a diminishing number of green areas and catchments, plus six months of near-constant rain --- you have a recipe for flood disasters which literally paralyze the city," the World Bank said in a statement when the study was released in April.
The Bank is supporting a flood management initiative with the local government.
Swathes of the teeming city were swamped and Jakarta's main airport was shut for hours earlier this year following heavy flooding caused by the combination of unusually high tides and the effects of subsidence from excessive extraction of groundwater.
QUEEN OF THE EAST
All this is in sharp contrast to the time when Jakarta, once known as the "Queen of the East," was renowned for its picturesque colonial houses, tropical tree-lined streets and canal network.
Today, the city is dotted with skyscrapers towering over run-down buildings and slums and is saddled with a host of problems, such as chaotic traffic, choking pollution and a massive influx of jobseekers each year.
Armi Susandi, a meteorologist at the Bandung Institute of Technology, who has researched the impact of climate change on Indonesia, estimates the submersion rate in the capital would be 0.87 cm a year, which is higher than an estimated average sea level rise rate of 0.5 cm a year until 2080.
Experts say the depletion of ground water has also allowed sea water from the Java Sea to seep into coastal aquifers, making the already filthy water saline.
Jakarta resident Maria Achmad said she and her family had been using ground water since 1995 because the piped water supply was erratic.
She was aware Jakarta was slowly sinking because of extraction of groundwater, but said her family didn't have a choice.
"I am concerned and worried about it. The Jakarta government should take action to limit the use of groundwater, especially by big restaurants and hotels which are the majority of groundwater users," she told Reuters.
"Second, we hope the government can fix the piped water system."
CLEARING THE CANALS
Faced with severe annual flooding, the Jakarta government has launched a multi-pronged plan that includes dredging the existing network of garbage-clogged canals and building a massive $560-million canal to stop the city from being swamped each year.
"We hope in two or three years we will manage to dredge all canals, revitalize the canals and, combined with the new canal, bring down flooding," Jakarta's governor, Fauzi Bowo, told Reuters.
"In previous years, when supply was short, a lot people tended to pump as much as possible. But now we have limited the usage of deep ground water because this is the main reason for land subsidence."
The river-dredging project overall would help reduce the flooded areas in Jakarta by up to 70 percent, but would still leave some parts of North Jakarta prone to flooding, Risyana Sukarma, a senior infrastructure expert with World Bank Indonesia, said on a Bank website.
"It is hoped that the dredging measures could return Jakarta floods to the previous cycle of once every 25 years provided that regular dredging maintenance takes place, and actions are to be taken to better manage solidwaste collection," Risyana said.
(For summit blog: http://summitnotebook.reuters.com/)
(Additional reporting by Telly Nathalia; Editing by David Fogarty)
