Government to build tunnels to free city from floods

JAKARTA (JP): The central government is planning to build two water tunnels at Sukasari village in Bogor, some 40 kilometers east of here as a scheme to settle flood problems in the capital, an official said on Friday.

Head of the Ciliwung-Cisadane River Development project at the office of the Ministry of Public Works, Adi Sarwoko Soeronegoro, said the tunnels would decrease the volume of water flowing into the city from the Ciliwung river in the upper Bogor and Puncak areas of West Java.

"It's common to see Jakarta inundated by floods if there is a huge volume of water from Bogor or Puncak.

"The two tunnels will retain the water and funnel it to the sea through Tangerang via the Cisadane river," he said.

Adi said the tunnels, with a capacity to incorporate water flows of 300 cubic meters per second each, would connect the Ciliwung river, the main river in Jakarta, and the Cisadane river, the main river of Tangerang, at a meeting point in Sukasari village.

Adi said the construction of the two tunnels, to start in 2001, would be financed by the Japanese Overseas Economic Cooperation Fund (OECF) through a 25-year-period loan.

"We haven't calculated the total cost of the project because it is still being reviewed by a Japanese consultant together with local experts," he said.

He added that soon after the project design is finished, the government would invite international companies to join the project through a tender.

The project will occupy about 10 hectares of land in Sukasari village, the closest meeting point of the Ciliwung and Cisadane rivers, including residential areas.

"The government should therefore remove the residents and provide a new site for their residence," he said.

The capital city has a "tradition" of annual floods especially during the rainy season, because about 40 percent of the city's 650 square kilometers is below sea level.

Because of its low contour, floods frequently visit the city even when there is no rain. Sometimes, several areas of the city are swamped if rain hits the Bogor or Puncak areas. These floods are locally known as banjir kiriman.

Data from the city's public works agency showed that there were 80 flood-prone locations in the city.

Adi said the two tunnels would technically settle the flood problems in Jakarta.

"Through the system, the tunnels will channel the water between the two rivers so that there won't be overflowing water," he said.

He said that each of the tunnels would be one kilometer in length and with an eight meter diameter, and this would be enough to carry about 300 cubic meters of water per second.

Adi added that the Ciliwung water flow reached 500 cubic meters per second, greater than its capacity of 300 cubic meters per second, when the city was hit by a massive flood in 1996. "Normally, the water flow is about 200 cubic meters per second."

"The condition has worsened due to the narrowing of the Ciliwung river as the result of the increasing number of squatters along its banks and the continuing erosion of its sediment," he said.

Adi said the ideal width of the Ciliwung river was between 60 meters to 100 meters, but in several areas it was only about 15 meters. (ind)