Flood canal plan years out of date experts say
Anissa S. Febrina, The Jakarta Post, Jakarta

Building the East Flood Canal according to the current plan, which was drawn up about 80 years ago, would only heighten the threat of flooding in the city, experts say.

Speaking on Tuesday at a public discussion on spatial planning, Trisakti University hydrology expert Erwin Iskandar recommended the start of the canal be taken further south.

“Both of the flood canals were designed according to conditions in Batavia, or old Jakarta, which had a total area of 2,500 hectares,” Erwin said.

“Now the city’s area is 65,000 hectares, the master plan must be revised.”

He said that by taking the start of the canal further south, where the land was higher, the flood risk in outer areas would be minimized.

Erwin said the existing West Flood Canal was only able to stop central areas of Jakarta from flooding because at the time of its construction the outer areas were not inhabited and therefore in less need of protection.

The West Canal Flood, designed by engineer Herman van Breen, was constructed in 1922 in response to the great flood in Batavia in 1918.

The canal cut through the Cideng, Krukut and Grogol rivers, channeling their water directly into the sea.

“Their main concern then was to keep people living in Weltevreden (now the Medan Merdeka area) and Menteng dry. Fortunately, the outer areas had not been inhabited,” Erwin said.

As witnessed today, outer areas like Manggarai, South Jakarta, and Jatinegara, East Jakarta, were among the most severely affected in both the 2002 and 2007 floods.

He said a similar condition could be created in outer areas of the East Flood Canal, like Cipinang in East Jakarta, if the project were to be built to the current plan.

During last month’s floods, 75 percent of the city was affected, almost four times the area affected in 2002.

For the city administration it is the perfect time to push forward with the canal plan.

The project, which is scheduled for completion by 2010, requires a Rp 4.124 trillion investment — both for land acquisition and the construction of the stretch of the canal that would cut through the Cipinang, Sunter and Cakung rivers.

As of today, only a 7.7 km stretch of the 23.7-km canal has been completed.

The canal, which has an upstream depth of three meters and a downstream depth of seven m, is projected to accommodate more than 390 cubic meters of water per second.

Environmentalists have criticized the plan as shortsighted and suggested either building lakes or developing a deep tunnel reservoir.

During the discussion, Tarumanagara urban planning expert Kemal Taruc highlighted the need for the city administration to develop a land contour map to calculate average depths across the city in a hypothetical flood.

“The simulation is needed as a precaution. We could warn residents based on the estimated depths,” Kemal said.

He added that previously urban planners and experts from the Agency for the Assessment and Application of Technology (BPPT) had offered to establish floodplain boundaries and flood depths through detailed analysis.

“Unfortunately, the administration does not even have a thing as simple as a land contour map.”

sumber: http://www.thejakartapost.com/detailcity.asp?fileid=20070303.C01&irec=0