Nearly half of Indonesia’s peatlands are vulnerable to flooding due to degradation caused by unchecked exploitation, with 6 million hectares (15 million acres) — an area twice the size of Belgium — classified as highly vulnerable, according to a new report.

The report, by peatland watchdog Pantau Gambut, examined three peatland-rich regions of Indonesia: the island of Sumatra; the Indonesian portion of the island of Borneo, known as Kalimantan; and the Indonesian half of the island of New Guinea, known as Papua.

Each region has distinct topographical and climate characteristics. Kalimantan features lowland coastal peat with high rainfall. Sumatra has both inland and coastal peatlands. Papua is the most complex, with extremely high rainfall and peatlands spanning inland, coastal and mountainous areas.

The report found that at least 25 per cent of Indonesia’s peatlands are highly vulnerable to flooding, with another 18 per cent classified as moderately vulnerable. This means 43 per cent of the country’s 24 million hectares (59 million acres) of peatlands are at risk, while only 57 per cent have low vulnerability.

Peatlands, as part of wetland ecosystems, are naturally waterlogged and capable of absorbing far more water than mineral soils. Peat can retain 100-1,300 per cent of its dry weight in water, while mineral soils typically absorb only 20-30 per cent. However, once degraded, peatlands lose their ability to retain water effectively.

This phenomenon, known as irreversible drying, turns standing water into uncontrolled runoff, leading to flooding.

“The floods occurring are not a natural cycle commonly found in peatland ecosystems,” said Wahyu Perdana, advocacy and campaign manager at Pantau Gambut. “These floods result from peatland degradation due to improper land use and the mismanagement of peatland functions.”

Another major contributor to peat flooding is subsidence — the compaction of peat, according to Kitso Kusin, a peat researcher at the University of Palangka Raya in Central Kalimantan province.

When peat is drained, usually by the digging of canals for industrial agricultural, it compacts, reducing its water absorption capacity, Kitso said. The dried-out layer of peat that remains is highly flammable, and it’s this one-two punch of subsidence and fire that’s historically been a key driver of peatland destruction across Indonesia.

Peat degradation

Peat subsidence and fires are driven by business expansion into peatlands. Despite efforts to curb this exploitation, deforestation in peatlands remains high, with nearly 50,000 hectares (123,500 acres) lost annually, according to Juma Maulana, a geographic information system researcher at Pantau Gambut.

Many peat hydrological units — peatland ecosystems naturally bounded by rivers and/or the sea and rich in carbon — overlap with industrial concessions. Pantau Gambut estimates that 8 million hectares (20 million acres), or 33 per cent, of these units fall within concessions, putting them at high risk of being drained and cleared. Once degraded, restoring peatlands to their original condition can take decades or even centuries, Juma said.

In many cases, restoration may not even be possible, no matter how much effort goes into it, Kitso said.

“Restoration cannot fully return peatlands to their original state but can slow down environmental degradation,” he said.

Coastal flooding

The impacts of peatland degradation aren’t limited to inland areas. The Pantau Gambut report found that land subsidence in degraded coastal peatlands has also increased the risk of tidal flooding.

Once natural barriers against seawater intrusion, these peatlands now contribute to the problem. As flood risks grow, freshwater reserves are also shrinking due to seawater contaminating groundwater supplies.

Riau province, on Sumatra’s eastern coast, is particularly vulnerable. Extensive coastal peat degradation has significantly altered the landscape, making floods more frequent and severe. Settlements, agricultural lands and entire coastal ecosystems in Riau are increasingly being lost to the sea.

Dumai, a coastal city in Riau where 80 per cent of the land consists of peat, frequently experiences flooding, even in the absence of heavy rain. In September 2024, a tidal flood inundated areas near the coast and the Dumai River.

“The flood this time is quite high. As a result, we couldn’t go to work,” Dumai resident Anwar, 44, said as quoted by local media.

Kalimantan

Kalimantan, another region heavily impacted by peat degradation, has also seen increasingly severe floods. In 2021, South Kalimantan province experienced devastating floods, with waters rising up to 3 meters (10 feet) in some areas, resulting in 15 deaths and the displacement of nearly 40,000 people.

The disaster caused an estimated 1.34 trillion rupiah (US$81 million) in economic losses, including damage to more than 24,000 homes, infrastructure and livelihoods.

The report found that floods in Kalimantan are no longer seasonal but now occur year-round, indicating permanent landscape degradation. Half of the region’s peatlands are highly vulnerable, with South Kalimantan being the most affected province. Nearly 80 per cent of its peatlands are severely degraded and at extreme risk of flooding, according to the report.

Recommendations

So far, the Indonesian government hasn’t addressed the flood risks associated with peatland degradation, Pantau Gambut said.

Authorities primarily associate peatland degradation with fires, overlooking the fact that drainage and subsidence are equally destructive, the NGO said. As a result, policies focus on fire prevention rather than addressing the hydrological collapse of peatlands, leaving flood risks unmitigated, Pantau Gambut said.

To prevent further degradation, policies must take an ecosystem-based hydrological approach, going beyond fire prevention to address broader impacts on hydrological cycles and flood risks, it added.

At the global level, stronger regulations on peatland ecosystems are needed, particularly within the EU Deforestation Regulation (EUDR). The EUDR, which takes effect at the end of this year, aims to prevent the import of products linked to deforestation and ecosystem destruction into the European Union. It requires companies to prove that commodities like palm oil, wood, rubber and soy weren’t sourced from deforested land after Dec. 31, 2020.

Indonesia, as the world’s largest palm oil producer and a leading timber exporter, is heavily impacted by this regulation. However, the EUDR’s current definition of deforestation follows the UN Food and Agriculture Organization’s model, which focuses on tree canopy cover loss rather than hydrological ecosystem destruction.

As a result, peatland drainage, subsidence and flooding — critical forms of ecosystem degradation — aren’t explicitly considered in EUDR assessments. This loophole allows companies to drain peatlands for plantations while still exporting to the EU, despite causing severe environmental damage, Pantau Gambut said.

If the EU fails to recognise peatland destruction as a form of deforestation, it risks enabling further degradation while also undermining Indonesia’s peatland restoration efforts, the NGO said.

At the national level, Pantau Gambut called on the Indonesian government to update its 2016 regulation on peatland protection and management to include flood risk indicators as a key measure of degradation. Currently, the regulation focuses primarily on preventing forest and land fires.

The government should also expand corporate accountability for peatland damage. Currently, companies are only held responsible for fire-related damage. Regulations should be expanded to hold them accountable for flood risks caused by peatland drainage as well, Pantau Gambut said.

“If such measures are not taken, it is not only endemic flora and fauna that will suffer,” Pantau Gambut said in its report. “Flooding caused by peatland degradation will also directly impact human survival. Everyone will bear the consequences if peatland ecosystems collapse — wetlands that are supposed to hold water will instead sink under water due to widespread environmental damage.”