Flood
North Jakarta's unrelenting sinking problem

Year after year, Jakarta sinks a few centimetres further below sea level. Flooding is on the rise, while many residents still inhabit the city’s most vulnerable areas. Indonesian journalist Dewi Safitri sheds light on the origins of this tragic situation and how many impoverished people find themselves without other choices.

The Netherlands is renowned for its system of canals, establishing a reputation as experts in canal architecture and water supply management. However, in Jakarta, once named Batavia by the Dutch colonials, there is limited evidence to support this claim. It’s not just expertise that’s being called into question; one study indicates that Dutch colonial policies have, in fact, contributed to the gravest threat facing Jakarta today: land subsidence along the northern coast of the island of Java.

During the colonial era, the Dutch constructed canals that connected the city centre with the outlying areas, where communities of native residents were located, including what is now North Jakarta. These canals served as the primary source of surface water for daily needs, but their proximity to the river’s estuary led to frequent accumulation of sediment deposits, resulting in blockages. Due to lack of cleaning and maintenance, these canals developed foul odours under the city’s high temperatures and became a breeding ground for diseases like cholera.

While the colonial European and affluent native residents had their water needs met through piped water systems, the underprivileged lacked access to such amenities. This issue persisted for over a century, and it was only nearing the 1900s that wells and water tanks began to be constructed in the coastal areas of Jakarta. At the end of the 19th century, residents were permitted to dig for groundwater. The exploitation of groundwater for clean water has continued to this day. More viable options for water provision, such as canal redevelopment and the establishment of piped distribution systems for clean water, have failed to materialise.

Sinking Land and Contaminated Water

Despite deteriorating water quality, the practice of groundwater drilling persists. "The water is yellowish, cloudy, has sediment in it and doesn’t smell too great. Sometimes, it even turns bluish," said Bani Sadar, the administrative head of RW 22 in Kampung Empang, at the port of Muara Angke in June 2023. Kampung Empang, situated near the sea, relies on groundwater drilling for nearly 90 per cent of its residents' water. “Sorry, but we have to dig for water. Where else can we get it? Most of us aren’t well-off and can’t afford to buy water in big amounts," added Bani.

Originally state-owned land, Kampung Empang has been occupied by residents who eventually obtained official building permits. "We may be poor, that's a fact. But we are not illegal; we have the permits," asserted Munarto, the administrative head of RT 03 in the same village. Over the past decade, Munarto and several community leaders from Kampung Empang have met with local officials, including the Governor, urging the installation of pipelines to provide clean water from the regional water company, PAM Jaya. Regrettably, to this day, no pipelines have been implemented in Kampung Empang. The local government has provided a few water kiosks supplied by PAM Jaya's tanks. Residents have to queue and pay 400 rupiah per litre for water. They have also voiced their discontent, claiming that the number of kiosks is insufficient.

In recent decades, scientists have revealed the connection between water issues and increasing inland flooding from the sea in North Jakarta with the assistance of satellite imagery. Prolonged groundwater extraction over centuries has caused the aquifer layer, which holds water in the ground, to become infiltrated with contaminated sea water. This is the layer that residents tap into to access water. With continued excavation, the aquifer layer diminishes, resulting in land subsidence. During his initial visit to North Jakarta in 1997, Heri Andreas, who currently serves as a lecturer at the Bandung Institute of Technology (ITB), was still a student in the Faculty of Geodesy (now integrated into the Faculty of Earth Sciences) at the same university. Studying the incursion of seawater onto the land, he accompanied his professor, Zainal Abidin, who conducted research on soil structure in the area from 1985 to 2011. "After successfully obtaining the model, we calculated that there is an average land subsidence of 2–15 centimetres per year, and sometimes even 20–25 centimetres. When combined with the increasing quantity of seawater and storm surges, one can imagine the impact on residential areas," said Heri. Land subsidence, the scientific term for sinking land, was identified by the ITB research team as the primary cause of the encroaching coastal flooding.

"Ceasing groundwater extraction is the best course of action," Heri stated. "What makes the problem complex is the lack of alternatives to groundwater exploitation. If the extraction of groundwater is halted, the supply of clean water will dwindle due to the contamination of both surface water and shallow aquifers."

The Threat of Sinking in 2050

Warsita is growing increasingly exasperated. His cherished double-door refrigerator, an essential tool for his work as a fishmonger at the Muara Angke market, is once again in jeopardy. Saline seawater, mixed with water from drainage channels and debris from the streets, has inundated his home in Kampung Empang. For three consecutive days, Warsita and his wife, Karmi, have battled to clean up the seawater that has sullied the floors, making them slippery, causing skin irritation, and corroding mixed metal objects like the refrigerator.

In the kitchen, Karmi adjusts the water hose. "We buy this water, two hundred and forty grand per month. We only use it for bathing and washing clothes, because it’s got a yellow tint," she says. The water is transported through a rubber hose about the size of an adult's wrist from a neighbour’s well about 50 metres away. "For cooking, we buy jugs of mineral water; it’s better,” she says with a weary smile.

Warsita and Karmi's account highlights the prevailing practice of groundwater extraction in North Jakarta. As the reserves of clean water in shallow aquifers have been depleted, drilling must now reach depths of at least 130 metres to access higher quality water. Consequently, the construction of one well can now cost 50-60 million rupiah. Studies conducted by Heri Andreas and his colleagues indicate that if this practice continues, 50 per cent of North Jakarta's area will be submerged by 2050. Other coastal areas in Indonesia, including Semarang, Pekalongan and their environs along the north coast of Java, where groundwater resources have been exploited, are predicted to face a similar fate. With the threat of climate change, rising sea levels, and natural phenomena such as high waves, these regions will experience acute water crises and prolonged tidal floods.

Foreign researchers like Hiroshi Takagi from the Tokyo Institute of Technology have reached similar conclusions. Since embarking on their research seven years ago, Takagi's team has recognised that averting ongoing land subsidence is imperative to address the threat of submergence. The primary strategies involve ceasing groundwater exploitation and implementing building techniques capable of withstanding tidal floods and land subsidence itself.

Unawarness of Imminent Peril

In March 2018,  Takagi’s team conducted a survey among 29 affected residents, asking: "Do you feel that your house is sinking?" It turned out that only about half acknowledged that their residential land was indeed sinking. The rest claimed to be unaware, including three residents whose houses had been inundated by waters reaching up to two metres high. This lack of awareness is likely to hinder efforts to save the area, such as implementing regulations to cease groundwater extraction.

I posed the same question to Warsita. He paused for a moment before stating that he had never heard anything about his area sinking. "I have been living here for 15 years, and I haven’t seen any sinking. My house is still standing," he earnestly replied. Warsita's perspective is not an isolated one. Djahruddin, the Secretary of the Pluit Sub-District Office, dismissed the predictions of his area sinking. "Where is the sinking you speak of? Yes, we face monthly floods due to high tides. If you live near the coast, that's normal. How could it suddenly sink?" Djahruddin mentioned the ongoing construction of a massive embankment project (National Capital Integrated Coastal Development - NCICD), spanning 37 kilometres, which will address the flood issues in Muara Angke.

Researchers like Heri Andreas and Hiroshi Takagi doubt that the giant embankment is the ultimate solution to Jakarta's sinking threat. "Yes, in the short term, it’s non-negotiable that the embankment is needed to protect residents from tidal floods. But in the long term, it merely acts as a ‘pain killer’, while the sea level continues to rise and the land sinks further down." There have been many instances of rising seawater breaching the embankment and repeatedly inundating the surrounding areas. Should residents be relocated if flooding worsens? Djahruddin, the Secretary of the Pluit Sub-District, stated that relocations have already been carried out multiple times. "Around 600 residents were moved to housing projects (Rusun) in Muara Angke thanks to the Su Tzi Foundation. Hundreds more were also sent to Rusun Marunda, but they eventually came back. They’re fishermen, you see, and it's too far for them to work if they live in Marunda." It seems that as long as they haven't been completely submerged, the residents will endure life in North Jakarta.

"If no anticipatory measures are taken, the area below sea level would extend to 80 percent within 20 years," writes Lisa Tarigan, Deputy Coordinator of Geological Planning Affairs, Raw Water Conservation, and Provision of Clean Water at the DKI Water Resources Agency. "That's why the DKI Governor Regulation regarding the zoning prohibition of groundwater exploitation is crucial."

However, enforcing this regulation in North Jakarta has proven challenging due to the fact that until last year, only 65 per cent of DKI's regions were served by PAM Jaya. One resident, who preferred not to be identified, expressed frustration with the repeated, unfulfilled promises. "They keep talking about putting in pipes, putting in pipes, putting in pipes. Officials, NGOs, students, journalists – everyone has come. But there's been no change, plain and simple!" he lamented.

According to the Global Risk Report in 2022, Jakarta has earned the unfortunate distinction of being the "Most Vulnerable City" among 576 major cities globally. This label is a result of the imminent perils posed by sinking, pollution, and extensive development. If this scenario were to unfold, the submergence of North Jakarta would directly impact at many as 1.5 million local residents.