The peak of the rainy season in Indonesia has caused damage across much of the archipelago, with major landslides in forested uplands.
On the north coast of Jakarta’s greater metropolitan area, families displaced by an upscale property development were relocated to a site that later flooded.
A landslide in January killed 26 people in one village in Central Java province, while a married couple were swept away last week in a flash flood in a nearby community.
Research predicts annual rainfall could increase 10% in volume by 2050 in Indonesia, while incidents of extreme rain could become more frequent.
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JAKARTA — The relocation site for families forced to make way for an upscale Jakarta property development was hit by a major flood this year, as extreme rain triggered fatal floods and landslides across Indonesia’s main central island of Java.
“This flooding is terrible,” said Ina, whose name has been changed to protect her identity.
“We don’t mind having to be relocated,” said Ina, a former resident of the village of Kohod in Tangerang district, on the northwestern outskirts of Jakarta. “But please give us proper facilities that are safe and don’t flood.”
The Pantai Indah Kapuk 2 (PIK2) development covers a planned 6,000 hectares (14,800 acres) and is under construction by a subsidiary of Indonesia’s Agung Sedayu Group.
Mongabay has previously reported on the land conflicts facing fishing communities around the construction area, where makeshift bamboo fencing has blocked fishers’ path out of Jakarta Bay.
A photo essay published in January by Indonesian daily Kompas documented the lives of flooded residents of Tanjung Pasir village, which is a few kilometers east of Ina’s home in Kolod village, on the opposite side of the PIK2 development.
Aerial footage of Kolod showed the entire village submerged under dark brown water.
On Jan. 28, floodwaters south of the development site also inundated the Sedyatmo toll road, the main access route to Jakarta’s Soekarno-Hatta International Airport.
Floods in Kohod village, Tangerang district.
Floods in Kohod village, Tangerang district, in January. Image by Irfan Maulana/Mongabay Indonesia.
Cloud storage
Indonesia’s main rainy season typically begins around November and lasts until March on Java, which is home to most of the country’s 280 million population.
Bouts of extreme rainfall this year have already triggered fatal landslides and floods across the island. On Jan. 20, extreme rainfall led to a landslide burying 26 people in a rural area of Pekalongan district, Central Java province. On Feb. 18, a husband and wife were killed by a flash flood in Temanggung district, also in Central Java.
Research shows land-use change, from selective logging of forests to large-scale property developments, can aggravate the probability of floods and landslides owing to greater instability of the topsoil and reduced drainage potential.
Historically, events linked to extreme rainfall are the most frequent threat to life compared with other disasters in Indonesia.
Data from Indonesia’s disaster mitigation agency, the BNPB, showed 315 people were killed and 49 recorded missing following 913 flood and landslide events across the world’s largest archipelago country over the course of 2024.
Fatalities following floods and landslides accounted for 86.8% of deaths attributed to all natural disasters combined last year, which include drought, earthquakes, volcanic eruptions and wildfires.
Researchers and policymakers say they expect the annual death toll linked to extreme rainfall to rise in the coming decades as climate change produces more frequent extreme weather events.
Bouts of extreme rain are predicted to become more frequent and the volume of annual rainfall over Indonesia is projected to increase by around 10% by 2050 as the climate changes.
Intense rainfall and flooding can induce pernicious health consequences downstream in communities, in addition to heightening the risk of sudden disasters like floods and landslides.
Research published last November showed a strong correlation in Bantul district, Yogyakarta province, between rainfall and diagnoses of leptospirosis, a bacterial infection caused by animal urine. Leptospirosis has a case fatality rate of 5-15%.
Local media in February reported anxiety among local health workers over recent floods fueling a dangerous rise in mosquito-borne dengue fever, which can be fatal in the very young and elderly.
Floods in Jabodetabek in early 2025.
Flooding in Greater Jakarta in early 2025. Image by Irfan Maulana/Mongabay Indonesia.
Flood the zone
Meteorologists say a climate pattern discovered in 1971 by U.S. National Center for Atmospheric Research scientists Roland Madden and Paul Julian may be to blame for the heightened rainfall afflicting much of Indonesia this year.
The Madden-Julian Oscillation weather pattern strengthens tropical convection over Indonesia around every two months, amplifying potential rainfall as the system moves eastward.
An Indonesian government study of three decades of daily precipitation gauges to 2017 showed the Madden-Julian Oscillation could increase rainfall by up to 50% in some parts of eastern Indonesia. The research was published in theInternational Journal of Climatology in 2020.
Meteorologists say this factor, combined with a weak La Niña, appears to be exacerbating the 2025 rainy season and prompting severe floods, just as the opposite El Niño phenomenon prolongs the annual dry season, sparking wildfires and drought.
Forecasting the magnitude of seasonal rain or heat can be difficult until the weeks or months before the onset of seasonal change; in late October last year the BMKG, Indonesia’s meteorology agency, said it expected the 2024-25 rainy season to be in the normal range for most areas.
Floods have inundated the coast of Tangerang district since the end of January, 2025.
Flooding in coastal Tangerang. Image by Irfan Maulana/Mongabay Indonesia.
Community notes
Overreliance on drilling wells into the aquifer for residential and commercial water means Jakarta is sinking by around 15 centimeters (6 inches) every year, faster than any other global metropolis.
The effect is worst on the northern coast, where king tides, storm surges and the longer-term threat of rising sea levels compound the problem.
In January, Ina’s makeshift home at the relocation site in Kohod village was inundated by waist-deep floodwater.
Her former home in another part of the village is now the site of a gated community of townhouses called the Florida Cluster inside the PIK2 development.
“This used to be rice field,” Ina told Mongabay Indonesia. “Now it’s a relocation site.”
Ina wanted to move her furniture to the new site were it not for the floods. She had complained to the village government but received no response.
Mongabay made attempts to contact Arsin, the Kohod village chief, but received no response. Just over a week later, police had charged Arsin with document forgery in a case centered on PIK2’s alleged grab of a large area off the coast.
Civil society groups say a lack of strategic city planning has aggravated the floods afflicting the Greater Jakarta area, which includes Tangerang district. The absence of waste management services means garbage blocks the metro region’s rivers and canals, a common trigger of local floods.
“Improvement in spatial and water planning across Greater Jakarta needs to happen,” said Jeanny Sirait, a Greenpeace Indonesia campaigner.
Jeanny cited data showing at least half of the flooding in Jakarta could be attributed to poor drainage.
“We found many water channels clogged with garbage,” said Taufik Syahzaeni, head of the Tangerang public works division.
Michael Sitanggang, who leads the disaster management agency’s logistics department, said in January that cloud-seeding flights over Jakarta had likely reduced rainfall by 60%.
“Our mitigation in the field is to train … the community in case of flooding and provide education,” Budi Muhdini, prevention lead at the Tangerang disaster management agency, told Mongabay Indonesia.
Dwi Sawung, campaign lead for planning and infrastructure at Walhi, Indonesia’s biggest environmental NGO, cited the PIK2 development as an example of land-use change that risked worsening flooding elsewhere.
Drains cut for the development could put pressure on nearby residential areas, Dwi said. Meanwhile, the clearing of mangrove forests removes a natural barrier against storm surges and coastal abrasion.
“The government is actually defending the developers, allowing the mangrove areas to be cleared, even though they should be protected,” Dwi said.
Kohod village flooded up to one meter (3.3 feet).
Kohod village flooded up to 1 meter (3.3 feet). Image by Irfan Maulana/Mongabay Indonesia.
Indonesian weekly Tempo, which has collaborated with Mongabay on past investigations, has reported that Henri Kusuma, a lawyer for families in Kohod village, had alleged evidence of collusion between village authorities and land brokers linked to the PIK2 developers.
Indonesia faces a housing backlog of at least 11 million units, according to the country’s housing ministry. A shortage of housing stock leads to unsafe living conditions that exposes families to overcrowding, which leads to health risks and economic instability that exacerbate social inequality.
A “Millennial” townhouse for sale in the Florida Cluster where Ina used to live starts at 700 million rupiah ($42,800), according to Agung Sedayu Group marketing materials.
Ina said that under her relocation agreement she would be given land with a title deed. But she hasn’t yet received the deed yet.
“Hopefully the government will see this,” Ina told Mongabay Indonesia. “Our relocation site is flooded.”
Banner image: Trees fallen due to winds and flooding. Image courtesy of Indonesia’s disaster mitigation agency.
A version of this story was first publishedhere in Indonesian on Feb. 8, 2025.
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