Dredging river estuaries can ease next year floods: Nedeco
Dredging river estuaries can ease next year floods: Nedeco
The Jakarta Post
Jakarta
An expert from the Netherlands Engineering Consultants
(Nedeco) said that floods in the capital could be eased by up to
80 percent next year if the city administration dredged at least
five of its river's estuaries.
"The estuaries' sediment that has reached a depth of three
meters significantly contributed to the flood in January and
February. Therefore, dredging them is a very important action,"
Nedeco hydrologist Gerard Pichel said.
Pichel was speaking at a workshop on Thursday on the results
of the Nedeco's quick reconnaissance flood study.
"Dredging the rivers up to 10 kilometers or more from their
estuaries should become the first priority for the city
administration," Pichel said.
The rivers and their estuaries that should be dredged include
Cengkareng Drain, Western Flood Canal, Ciliwung River, Sunter
River, and Cakung Drain.
Dredging 10 kilometers of the rivers' estuaries would smooth
the rivers' water flow as sediments in their upper parts would be
eroded and taken away down the stream, he said.
Nedeco estimates that the government should spend Rp 510
billion on dredging the five estuaries and 65 kilometers of
waterways as well as cleaning up the other parts.
According to Nedeco's study, 10,000 hectares of Jakarta were
flooded in February at a cost of around Rp 10 trillion.
"If the city completed the dredging project before the next
rainy season (December), I can guarantee that some 8,000 hectares
of the area would not be inundated," said Pichel.
Other Nedeco's recommendations included widening the Manggarai
gates, improving the structure bottlenecks, minor detention
measures, retention reservoirs, and full maintenance and
rehabilitation of the drainage system.
Nedeco, which recommended the construction of the Eastern
Flood Canal in 1973, also said that the Indonesian government
should also start long term programs, like river improvements and
the development of the Eastern Flood Canal. It estimates that
this project will cost Rp 5.7 trillion.
"If we implement the short-term program, it does not mean that
we stop the long-term program like development of the Eastern
Flood Canal," Pichel said.
The construction of the West Canal, 17 kilometers long, was
completed by the Dutch in 1918. But the width of the channel has
been narrowed considerably, disrupting the flow of water through
it.
Meanwhile, Koss Wieriks, an official of the Netherlands'
Ministry of Transport Public Work and Water management said that
the changes in land use and changes in the rivers significantly
contributed to the flooding.
"The rain (in Jakarta) is falling in more or less the same
intensity as hundreds of years ago. But changes in the land use
and changes in the rivers have caused higher levels of the run-
off of the rainwater," he added.