Jakarta aims to improve flow of Ciliwung river as part of flood mitigation efforts
Observers have urged the authorities to double down on flood control measures to ensure the Indonesian capital continues to be a magnet for investments and a liveable space for residents.
BOGOR/SUMEDANG, Indonesia: Flood-prone Jakarta aims to improve the flow of the Ciliwung river and complete the widening of its banks by the end of this year, as part of mitigation efforts.
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The 120km-long waterway crosses the Indonesian capital and the neighbouring province of Bogor before finally flowing into the Java sea. It played an important role during the early settlement of Jakarta, but has now been blamed for the floods in the economic epicentre.
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Observers have urged the authorities to double down on flood control measures, to ensure the city continues to be a magnet for investments and a liveable space for residents.
PREVENTING OVERFLOWING
Flood management in the city begins further upstream in Bogor, which is about 40km away.
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In 2022, authorities completed the construction of the Ciawi and Sukamahi dams in Bogor, the first dry dams in Indonesia.
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These are catchment areas designed to hold excess water from the Ciliwung river to mitigate downstream flooding. When there is prolonged intense rainfall upstream, the water level in the dam rises and is retained temporarily.
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Water continues to be released at a slow and controlled rate through gates located at the outlet. This prevents the river downstream from overflowing and flooding nearby residential areas.
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By retaining water in its catchment areas, both dry dams are able to reduce floods in Jakarta by 30 per cent, according to Indonesian authorities.
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“So, this conduit functions to limit the discharge flowing downstream towards Jakarta,” said Mr Bambang Heri Mulyono, head of the River Basin Management Office (Ciliwung-Cisadane).
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“When the water level in this dam rises above the tunnel, damming occurs. There is restriction on discharge flowing downstream.”
While the dry dams may ease the discharge of water flowing to Jakarta, flood control efforts are still needed downstream, said experts.
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This comes as residential areas near the Ciliwung river in Jakarta continue to get inundated.
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Over the years, parts of the river have narrowed considerably due to human settlement near the banks, causing water to overflow easily.
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Now, authorities are widening parts of the river by 35m to 50m, and back to its original condition. But only 17km out of 33km of the Ciliwung river in the capital have been reconstructed so far.
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Highlighting various challenges, Jakarta Water Resources Department acting secretary Hendri said: “There is the problem of 'girik' (customary land control), there is the problem of double certificates, there is the problem that residents don't want the land to be taken away.
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“But we still carry out land acquisitions. We always approach it with socialisation. We explain why we need to do it. We also work together with BPN (National Land Agency) for all transactions.”
RIVER NORMALISATION
Among the districts included in this river normalisation programme is Manggarai in South Jakarta.
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Under the project, many families living in the area next to the Ciliwung river have been evicted.
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“The important thing is that I have a place to stay. Where should I live? There is no other place for me,” said Manggarai resident Sani, who has not been evicted yet and hopes to live by the river.
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“My hope is that I won't be evicted. I've been living here for 67 years. I hope that, instead, homes here are improved and made permanent.”
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Urban planning expert Nirwono Joga from the Trisakti University said other rivers in Jakarta also need to be normalised to overcome the perennial flooding.
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“Jakarta has 13 rivers. If the Ciliwung (river) is completely normalised successfully, it will be successful in reducing the impact of flooding in Jakarta,” he added.
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“This will be a good example of the normalisation of 12 other rivers, including the big rivers Pesanggrahan, Angke and Sunter, which can also be normalised in the same way as the Ciliwung river.”
USING DAMS FOR CLEAN ENERGY
Meanwhile, Indonesia is building more dams.
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The Public Works and Housing Ministry has set a target to complete a total of 61 dams by the end of this year.
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These dams are being built to address food and water security concerns, and also provide low-carbon hydroelectric power.
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Hydropower energy production has been the country’s most significant contributor of renewable energy.
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Hydropower dams are situated at a higher elevation and use the potential energy of water to produce electricity.
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The gravitational force creates strong pressure and rotates the blades of the turbine. This, in turn, spins the generator which produces electricity.
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The water flushes out past the turbine through the outflow and into the river bed to continue its journey.
The Jatigede hydropower plant, located in Sumedang in West Java province, has a capacity of 110 megawatts (MW).
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The plant uses water from the Jatigede dam, the second biggest in Indonesia, and will support the electricity grid between Java and Bali.
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“This hydroelectric power plant is only functional during peak hours from 5pm to 10pm, because we use water from the Jatigede dam,” said Jatigede Hydroelectric Power Plant assistant project manager Dinar Pradipto.
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“We match the time when water is released for irrigation needs downstream, and we use it at the same time to drive the turbine and generator.”
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The Jatigede dam has a water surface area of more than 4,100ha, which makes it suitable to be used to capture solar energy.
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There are plans to install floating solar power panels to complement the hydroelectric power already generated by the dam.
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“The plan for a solar power plant has also been carried out by PLN (State Electricity Company) and it is targeted that by 2024, a solar power plant with a capacity of 100MW will be operational,” said Jatigede Dam Management Unit head Yuyu Wahyudin.
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“This means that approximately under 10 per cent of the inundation area will be used for the floating solar power panels.”
ADDRESSING FOOD, WATER CONCERNS
Besides generating clean renewable energy, the Jatigede dam also provides water and food security.
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The reservoir supplies 3.5 cubic metres per second of drinking water to meet the needs of over 600,000 residents in the surrounding areas.
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In addition, more than 1 million farmers benefit from the Jatigede dam irrigation system.
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Water from the dam is able to irrigate over 90,000ha of farmland in three regencies - Majalengka, Cirebon and Indramayu.
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Indramayu regency, for instance, produced more than 819,000 tons of rice last year, making it the biggest rice producer in the West Java province.
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“It is very helpful because farmers now do not worry if there is no rain. In the past, if there was no rain, we needed to prepare a machine or a pump to wet the rice fields,” said the 45-year-old.
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“Now I do not worry about water problems because there are improvements in irrigation, farmers can successfully harvest up to twice (a year).”
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However, some residents have also lost their livelihood because of the dam development. Among them is 63-year-old Mahfuddin, whose rice farm was submerged by the project.
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He now breeds fish in a floating fish farm in the catchment area. While it provides him with a means to get by, the fish farm is currently illegal.
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“There has been too much sadness. I was pushed around a lot (by municipal police) threatening to dismantle the fish farm,” said the resident.
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“I did not resist. I have a lot of hope in the government to make this (floating fish farm) legal, so that I won't face any more problems.”