Jakarta Will Erect Seawalls To Stem Waters

Dofa Fasila Jakarta Globe 29 Nov 11;

In the wake of days of tidal flooding in North Jakarta, Governor Fauzi Bowo says he has short-term and long-term plans to deal with the problem facing the capital’s ever-expanding coastal residential areas.

The short-term plan is to raise the height of seawalls, and the long term plan is to, well, build higher sea walls.

Since seawalls might promote more development, however, his plan seems at odds with advice from local environmental groups, who in the past decade have said the building of residential enclaves and hotels on coastal mudflats has exacerbated tidal flooding in Jakarta.

Fauzi’s seawall plan is also at odds with the recommendations from the World Delta Summit last week in the capital, where experts warned not to ignore the natural function of mudflats in cities built on river deltas, such as Jakarta.

“That’s why it’s important to designate delta areas as an integrated part of a city’s wider spatial planning, not as an independent sector,” Jan Sopaheluwakan, a researcher with the Indonesian Institute of Sciences (LIPI), said during the conference.

But according to Jakarta’s deputy head of public works, Novizal, the flooding stems from too little development, not too much.

“At Pantai Mutiara [in North Jakarta], there are still many reclaimed land subdivisions which have not been built on,” he claimed. “When the tide comes in, the water can enter via the undeveloped blocks. If all the subdivisions were built on, then Pantai Mutiara and its surrounding areas would be safe from flooding.”

In the short term, Fauzi said the city would respond to the floods, which are affecting residents along Jalan R.E. Martadinata and in the upscale Pantai Mutiara area, by raising the seawalls. The tactic, he said, would give the city and central governments time to approve a new approach that he dubbed the Jakarta Coastal Sea Defence Strategy, which involves the construction of “giant seawalls” along the city’s north coast.

Fauzi said he visited the area currently flooded by about 2.5 meters of seawater, and that local residents had agreed to take the initiative and help raise the existing seawalls by several tens of centimeters.

“I have checked the area to the north of the Pluit water pump, which is always affected by tidal flooding,” Fauzi said on Monday. “Two days ago, that area was safe because the seawalls had been raised to three meters.”

The governor said the latest measures were only temporary and will last for a few years, while his administration expected the Jakarta Coastal Sea Defence plan to help with flood prevention in the next 25 to 100 years.

“I sent the report to the president the other day,” he said. “I think the city administration, with the public works department, can carry out the plan.”

As for funding, he said the giant seawalls would not require any money from the state budget. Instead, the funding will come from private interests who will work with the government.

More recently, NGOs have pointed to GPS data which shows that the rate of land subsidence along Jakarta’s northern edge, for example at Pantai Indah Kapuk, averages 11.5 centimeters per year.

Ironically for developers, experts believe the subsidence is mostly due to excessive groundwater extraction by the very housing estates that are threatened by flooding.