The Jakarta Post
Experts on urban planning and flood mitigation have urged the public to engage in a healthier, more comprehensive discussion about flood mitigation instead of riding on a political spat between Jakarta Governor Anies Baswedan and Public Works and Housing Minister Basuki Hadimuljono regarding a 17-kilometer stretch of the Ciliwung River, a minor issue in Greater Jakarta's overall flood problem.
Climate scientists have warned that the extreme weather caused by climate change that happened in Indonesia at the turn of the year may become the "new normal" of the future. The warning has led to a conversation about flood-mitigation strategies far beyond the spat among officials and politicians about river "normalization” or “naturalization" programs.
Minister Basuki has pushed for the so-called river normalization program, in which the ministry will widen the Ciliwung River, install concrete piling along the river and build a road for motor vehicles, all of which will require evictions.
Meanwhile, Anies, who pledged not to carry out forced evictions in his election campaign, halted the procurement of land needed for the project and offered naturalization instead, which replaces concrete piling with river stones and transforms riverbanks into green public spaces.
A waste of time
The ongoing debate will be a waste of time if officials do not address the underlying problems of recurring floods, namely climate change, land conversion to resorts and villas in the upstream area and rapid development in the downstream, which leads to massive groundwater extraction from deep aquifers, according to Bosman Batubara, a PhD student at the IHE Delft Institute for Water Education in the Netherlands, who is doing a doctoral thesis on flood management.
“The problem is getting more complex because of inadequate care of waterways coupled with garbage dumping and sedimentation,” Bosman said.
“But none of the technical solutions talk about power, which is the core problem. Flooding in the cities is the result of a process whereby power becomes an inevitable element,” he added.
Rita Padawangi, an urban expert at the Singapore University of Social Sciences (SUSS), added an argument saying that the shrinking quantity and quality of lakes in the Ciliwung watersheds had reduced the water infiltration rate.
She cited the book Banjir Kanal Timur, Karya Anak Bangsa (East Flood Canal, Work of the People) authored by senior Kompas journalist Robert Adhi Ksp on the number of lakes in Greater Jakarta, which had declined from a total of 240 lakes covering 2,337 hectares in 2004 to 1,462 ha with 184 lakes in 2009. Only a small proportion of these are in good condition.
Hydrologist Fatchy Muhammad of the Indonesian Water Society stressed that all relevant stakeholders must change their paradigm into achieving zero-runoff by installing abundant infiltration wells, given the interconnected problems of drought during the dry season.
The typical geological structure of Greater Jakarta land has good potential to absorb water until the pressurized aquifer layer at a depth of over 200 meters "because it comprises layers of clay and sand,” Fatchy said.
The Jakarta administration recently stated that the city requires 1.8 million vertical drainage units installed throughout the city, except in North Jakarta and Thousand Islands, by the private and public sectors and by individuals.
Only some 2,000 vertical drainage units have reportedly been installed. Fatchy questioned the pace, doubting that the city would ever reach its 1.8 million-unit target.
The administration has issued regulations to oblige entities that utilize surface water or extract groundwater from more than 40 meters in depth, but enforcement is patchy, he said.
Both vertical and horizontal needed
Vertical drainage alone, however, will not be enough.
At some point, the soil may saturate, hence runoff absorption will be more effective for light to medium rainfall intensity. During extreme rainfall, utilization of waterways that channel water to the sea—such as canals or rivers—is inevitable, according to Dwita Sutjiningsih, a professor of hydrology at the University of Indonesia.
“Comprehensive efforts to cope with any rainfall intensity are needed because rain is actually a blessing, right?” Dwita asked.
Drainage installation is sized according to the probability of occurrence of expected peak discharge. Climate change that results in extreme weather will lead to changes in peak discharge projection.
In addition, land development contributes to the changing design calculation of a drainage system.
"Infrastructure is built to complement each strategy. A [periodic] review of the built infrastructure should be made in line with the current situation," Dwita said. “The difficulty is we don’t have enough long range data to understand the trend."
The ministry has come up with infrastructure solutions for flood mitigation, with the highlighted ones being river normalization, water tunnels and the construction of Ciawi and Sukamahi dry dams in West Java.
On Jan. 2, Minister Basuki claimed that the normalized part of the Ciliwung was "relatively" safe from flooding after he inspected the area from above. However, Isnu Handono from community organization Ciliwung Merdeka, which advocated on behalf of residents in Bukit Duri, South Jakarta, during the forced evictions for the ministry's project in 2016, said that the normalized area was flooded. He had a video filmed in the early hours of Jan. 2 that showed a deluge of water overflowing from Ciliwung, overwhelming the concrete embankment and flooding the inspection road built by the ministry as part of the normalization program.
Naturalization needs land too
Another expert said that while naturalization could work, Anies would need to procure land to make room for the green space. Land procurement in many projects in Indonesia usually leads to forced evictions.
“River water always needs areas for runoff corridors during heavy downpours, so there should not be permanent activities on riverbanks. Non-permanent things like green spaces or sporting fields are still possible,” said Hadi Susilo Arifin, an urban water expert from Bogor Agricultural University.
With his pledge to halt forced evictions, Anies pinned high hopes on the ministry's projects to build the Ciawi and Sukamahi dry dams in the upstream when reporters asked about flood-mitigation strategies.
Land acquisition for the projects has progressed 90 percent and the physical construction is at nearly 45 percent, according to the ministry. The project is expected to be complete by the end of 2020.
The two dry dams have a total capacity of 8 million cubic meters, which is expected to reduce by 30 percent the water discharge from the upstream areas, hence water discharge arriving in the capital will be reduced by about 12 percent.
“I worry that the public will have great expectations about the project without knowing the complete information,” Dwita said, pointing out that the dam's capacity was actually much less than the Jatiluhur dams that contain up to 3 billion cubic meters.
Above all the correlated issues, Armi Susandi, a meteorology and geophysics expert from the Bandung Institute of Technology (ITB), urged the government to ensure every development in every part of the country is in line with disaster risk-management principles, in which short-term disaster mitigation should be a priority.
“The government should also give incentives to people regarding disaster mitigation, as well as promoting climate-change adaptation. For example, building the necessary facilities that will ease the impact from climate-induced disasters,” Armi said.
Rita of SUSS, who was involved in collaborative international research on the Ciliwung River project with other scientists, that aimed to develop solutions to address flooding, water quality and ecology with local population involvement, expressed a similar suggestion.
“Identify the capabilities of residents that can be empowered to actively participate in disaster mitigation and focus on increasing public resilience for extreme occurrences," Rita said. "Because any mitigation efforts will not completely eliminate floods under extreme conditions."