Agnes Winarti, The Jakarta Post, Jakarta | Mon, 02/02/2009 4:05 PM
Dredging Jakarta's rivers and canals could reduce flooding in the city by 40 percent, an expert from the Netherlands says.
"Only by dredging them will we be able to reduce the effect of flooding by 40 percent," Peter Vroege told The Jakarta Post in a recent interview.
Vroege leads a team of Dutch experts assisting the city administration's efforts to dredge Kali Mati and Kali Pademangan canals in North Jakarta.
"Most Jakarta rivers and canals have silted up by up to 50 percent *of their original depths*," Vroege said, quoting a 2007 study by the city's river management body and Dutch experts under the Partners for Water program.
According to the study, Jakarta has 18 main canals and over 500 smaller canals that are 2 to 15 meters in width. The study estimates that the city's network of canals has become silted up with 9 million cubic meters of sediment and waste.
The city administration said the city's canal network performed only at 50 to 70 percent of its capacity.
The system can accommodate a maximum of 50 millimeters of rainfall in a day. However, daily rainfall exceeding that amount is not uncommon during the rainy season.
Vroege said the canals should be dredged regularly.
"In Holland, the canals are dredged once every five or 10 years.*But*how frequent the dredging is will depend on whether people stop throwing garbage into the canals," he said.
"That's why the administration needs to establish a better waste system and keep*reminding the people*not to throw away garbage into canals."
City Public Works Agency head Budi Widiantoro said his office had removed 350 cubic meters of mud from the Kali Mati and Pademangan canals, which it then dumped into a nearby swamp in Ancol, also in North Jakarta.
"After the two canals, we will *prioritize to* dredging the canals in Utan Kayu in East Jakarta, Kebon Bawang in North Jakarta and Krukut Bawah in Tanah Abang and Rawa Kerbau in Cempaka Putih, both in Central Jakarta," he said.
Budi said that this year the administration had allocated Rp 1.5 billion (US$133,928) for dredging medium-size canals, including Kali Mati and Kali Pademangan.
The administration has also earmarked Rp 200 billion to dredge Ciliwung River, which runs through Manggarai, Gunung Sahari and Gajah Mada.
"We will start that in May," he added.
The administration is also awaiting the disbursement of a World Bank loan worth US$150 million from the central government as part of a project to dredge 18 key drainage canals and retention basins.
Of the loan, $5 million is allocated for procuring heavy equipment, and the rest is for operational expenses.
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