by Bambang Purwanto
JAKARTA, Dec 12 (NNN-XINHUA) – Indonesia’s capital city, Jakarta, was expected to overcome its lingering problem of flooding, as two dry dams are now under construction, in its outskirt areas of Ciawi and Sukamahi in Bogor town, West Java province.
Almost every rainy season, Jakarta is flooded, not only because of heavy downpours, but also spates from the pluvial town of Bogor, which stream down to the capital city.
This week, two-day rains fell in Jakarta, Bogor and surrounding areas, causing floods that affected hundreds of houses after Ciliwung river, whose upstream is located in Bogor, overflowed.
Jakarta’s Governor, Anies Baswedan, recently said, he would rely on the two dams in Ciawi and Sukamahi to overcome floods that flow through Ciliwung river, whose estuary is in the Jakarta Bay.
“We receive waters from the upstream when heavy rains fall. Thus what should be done is building the dry dams,” the governor said.
According to him, if construction of the two dams were done, rain waters from Bogor could be blocked, and the volume of waters flowing to Jakarta is not so big.
“If the dry dams are completed, about 30 percent of the flooding problems will be solved,” the governor added.
The constructions of the dry dams in Sukamahi and Ciawi, which are part of the Jakarta flood control master plan, are expected to be completed in 2021.
The projects are the government’s effort to reduce the vulnerability of Jakarta to floods, carried out by the Ministry of Public Works and Public Housing, through the Ciliwung-Cisadane River Basin Centre.
Public Works and Public Housing Minister, Basuki Hadimuljono said, the operation of the dry dams would be different from those of other dams, as they (the dry dams) would only be filled with waters during the rainy season, and empty during the dry season.
The Ciawi and Sukamahi dry dams, which would be the first of its kind in Indonesia, are used not for irrigation or raw water, but for increasing the capacity of flood mitigation.
According to the website of the Public Works and Public Housing Ministry, the Sukamahi dam was expected to accommodate 1.6 million cubic metres of water with an inundated area of 5.23 hectares, and the Ciawi dam would have a volume of 6.05 million cubic metres with a flooded area of 30.40 hectares.
The basins were designed to reduce the flood discharge to Jakarta by blocking the flows of waters from Mount Gede and Mount Pangrango in Bogor, before arriving at the existing Katulampa dam in the town and streaming down to Ciliwung river, which flows through the heart of the capital city, whose population now reaches more than 10 million people.
In addition to physical infrastructure development, the ministry also has a telemetry flood early warning system, that records the water level at several floodgates and observation posts, such as Katulampa Post, Depok Sluice, and Manggarai Floodgate. The alert level and authority to open and close the floodgates have also been set.
The ministry’s special staff for water resources, Firdaus Ali said, the Ciawi-Sukamahi dry dams could only be used by the end of 2022.
According to Ali, if the dams were operational, floods in the capital city due to Ciliwung river’s overspill could decrease between 17 and 29 percent from normal condition.
“The volume of waters would automatically reduce more, if efforts to normalise Ciliwung river run well,” he told local media.– NNN-XINHUA
