Indonesia's 281,253 Kilometers of Peatland Canals Deepen Flood, Fire and Climate Risks

A drainage network changes how water moves

A network of 281,253 kilometers of industrial canals cuts through peat ecosystems in Sumatra, Kalimantan and Papua, according to Indonesian environmental group Pantau Gambut. Dug to dry land for oil palm and pulpwood plantations, these channels are also changing how rain reaches rivers, farmland and homes. The group's analysis links peat drainage to rising flood risk across Indonesia.

Peatlands naturally hold water and release it slowly. When canals lower their water tables, the soil dries, decomposes and sinks. Rain then moves through a landscape with less capacity to store it, while drainage channels carry runoff toward rivers and settlements. The same areas can burn during dry months and flood during wet months.

Pantau Gambut places much of this drainage network inside commercial concessions, areas where companies have permission to operate. Nearly 4 million hectares of oil palm plantations occupy peat, alongside about 2.5 million hectares of industrial plantation forests. Between 2015 and 2022, more than 500,000 hectares of peatlands were converted to monoculture, plantations dominated by a single crop.

The consequences extend beyond plantation boundaries. Communities in Riau and parts of Kalimantan describe floods arriving more often, lasting longer and occurring outside the peak monsoon months. Heavier rain in a warming climate is part of the problem, but drainage changes the ground itself and the routes water takes across it.

Why drained peat sinks and floods

Peat forms when dead plant material accumulates in waterlogged ground. With little oxygen available, decomposition is slow, allowing carbon to build up over centuries. An intact peat swamp acts like a living sponge: its surface rises and falls as it absorbs rainfall and releases water gradually.

Canals lower the water table, the level below which the ground is saturated. Oxygen can then reach deeper layers, allowing peat to decompose and release carbon dioxide. The surface also compacts and sinks, a process called subsidence. Peat lost through oxidation and fire cannot return within any meaningful planning horizon.

An intact swamp spreads stormwater and releases it downstream over days or weeks. A drained landscape moves rain more quickly through its canal network, while the sinking surface reduces the ground's ability to hold water. Rivers can rise faster than they can carry that water away.

Coastal peat faces another pressure. As the ground sinks relative to the sea, tidal flooding and saltwater intrusion become more likely. Inland and coastal communities can therefore face both higher flood peaks and longer periods of inundation.

Canal density helps explain the damage

Scientific mapping supports the picture of extensive drainage. A regional analysis using satellite images with fine detail and machine learning found drainage in at least 65% of Southeast Asian peatlands across all land uses. Machine learning allowed researchers to identify patterns in the imagery and map the drainage network.

Areas with dense canal networks had subsidence rates around 3.2 times those of areas without drainage. Including canal information improved predictions of subsidence much more than using land use categories alone. Whether an area is labelled forest or plantation tells only part of the story; the channels carrying water out help explain how quickly its surface sinks.

Pantau Gambut identifies 10 firms whose operations on peat raise flood risk beyond their concession boundaries. Their products enter international supply chains for palm oil, paper and tissue, connecting changes in Indonesian water systems to goods bought around the world.

Import rules intended to curb deforestation do not consistently treat peat drainage as deforestation. Buyers can therefore miss damage caused by lowering water tables, including in places where some trees remain.

Fire and flood follow the same drainage

Indonesia's drained peatlands face a cycle of disasters. Canals lower water tables, and logging opens the forest canopy, leaving the surface more exposed to drying. Sparks from land clearing or nearby fires can ignite the peat. Fire can spread below ground, making it difficult to detect and extinguish before smoke thickens.

During wet months, those same drained catchments carry rainfall rapidly toward rivers and settlements. Communities face smoke and haze that send people to clinics when rain is scarce, followed by floodwater that damages homes, roads and crops when rain returns.

Of the 3 million hectares of peatlands that burned between 2015 and 2024, more than 1.2 million hectares were inside concessions. That is more than 40% of the burned area, using the figures cited in Pantau Gambut's analysis.

Separate assessments put 43% of Indonesia's roughly 24 million hectares of peat at risk of flooding, with 6 million hectares highly exposed. South Kalimantan has experienced widespread inundation since 2021. In low lying parts of Riau, residents describe floodwater returning sooner, leaving less time to recover between disasters.

The damage has accumulated over years

The changes described by Pantau Gambut cover several periods, linking plantation expansion, fire damage and repeated flooding. The figures show how pressures have accumulated across Indonesia's peat landscapes rather than emerging from a single storm.

• 2015 to 2022: More than 500,000 hectares of peatlands were converted to monoculture.
• 2017: A ministerial regulation allowed companies to avoid restoration duties when fires occurred inside their concessions, shifting responsibility to the government.
• Since 2021: South Kalimantan has experienced widespread inundation.
• 2015 to 2024: Some 3 million hectares of peatlands burned, including more than 1.2 million hectares inside concessions.

For communities, repeated damage means that recovery from one season can be interrupted by the next. Dried and sinking ground remains vulnerable when the weather changes from a period of scarce rain to heavy rainfall.

Canal water carries a climate cost

Degraded peatlands account for about 5% of annual greenhouse gas emissions caused by people worldwide. Fires release stored carbon, while drained soils continue emitting carbon dioxide as peat decomposes. Research in Indonesia also identifies emissions from the water inside drainage canals.

Laboratory experiments using canal water from peatlands in West Kalimantan measured carbon dioxide produced by microbes and by sunlight breaking down dissolved organic carbon. Dissolved organic carbon is carbon from organic material carried in water. Once peat carbon enters a canal, some of it can be converted into gas before the water reaches a river or the sea.

The researchers estimated that each square meter of canal surface releases about 70 milligrams of carbon dioxide per day. Around 35% of the carbon that dissolves into canals is released back into the atmosphere before reaching rivers or the sea.

Jennifer Bowen, a lead author of the study and a postdoctoral scholar with Scripps Institution of Oceanography and Stanford University, said the canals add a climate cost to emissions from dried soils:

These canal systems are likely a significant source of carbon dioxide emissions on top of the emissions from dried peat soils, and we are probably underestimating the climate impacts of degrading these systems.

Carbon released from canal water also means less peat carbon reaches the ocean, where some fraction might otherwise be stored. Climate inventories that count smoke from fires but leave out soil oxidation and canal emissions will understate the climate impact of peat drainage.

Protection rules leave gaps in responsibility

Indonesia has rules intended to protect peat, but much of that protection sits in government regulations rather than statutory law. Higher level laws can override those protections, leaving room for companies to avoid obligations.

A 2017 ministerial regulation allows companies to avoid restoration duties if fires occur inside their concessions, shifting responsibility to the government. Damage is also often recognized only after peat burns. Draining peat is not consistently treated as damage that triggers sanctions, even though lowering the water table starts the processes that dry and weaken the soil.

Pantau Gambut urges authorities to recognize drainage, deforestation and flood outcomes as indicators of harm alongside fire. Stopping damaging canals and requiring water tables to recover would address the changes that precede larger disasters.

Civil cases connected to haze have been thrown out in several instances, leaving victims without a remedy. Without clear penalties for lowering water tables, companies retain a financial incentive to drain peat for production, while communities face the costs of fire and flooding.

Villages face losses beyond damaged homes

Farmers in South Sumatra describe upstream canal cutting changing seasonal water flows, ruining rice paddies and reducing fish catches. In low lying settlements along the Musi River and across Riau, residents report water rising higher with each storm and taking longer to recede.

Many residents cannot abandon their homes. Their work and family networks tie them to places where pumps, repairs and frequent evacuation have become part of daily life. Floods disrupt markets and schools, while smoke from peat fires harms health and interrupts earning a living.

Small repairs that once held back floodwater struggle against a deeper change in the landscape. Informal dikes and drains provide little relief when land continues to sink and canals bring rainwater downstream more quickly. The problem reaches beyond an individual house, field or village drain.

Communities therefore need water management that takes account of upstream canals and the wider peat landscape. Plantation boundaries divide ownership and responsibility, but water moves across those boundaries.

A Sumatra trial shows what rewetting can achieve

A restoration trial lasting seven and a half years in Sumatra offers evidence that damaged peat can be managed differently. Researchers raised groundwater in a former plantation by installing 257 dams made from compacted peat across 4,800 hectares.

Subsidence rates fell by about half, and emissions declined. In the wettest areas, 57 native peat swamp tree species regenerated without planting. Their return indicated that conditions were becoming more suitable for peat swamp forest.

The study recommends rewetting in steps, avoiding prolonged deep inundation and allowing native forest to recover on its own where possible. Raising water levels carefully matters because restoration must bring back wet conditions without leaving the landscape under deep water for long periods.

Canal blocking is one part of that work. Concessions remaining in production can set water table targets, use automatic monitors and publish the results. Pantau Gambut's proposed response also includes stopping new canals on peat and making permanent water table recovery part of fire prevention, alongside seasonal patrols.

Government agencies and companies can coordinate dam placement across concession boundaries. A peat dome, the raised body of peat that shapes water movement, functions as a connected landscape. Restoration needs to follow that water system rather than stop at a property line.

Livelihoods must work with wet ground

Paludiculture, or cultivation on wet land, offers a way to keep farming while maintaining high water tables. It replaces crops that require dry soil with species that tolerate wet conditions, helping communities take part in restoration without giving up their livelihoods.

Farmers in South Sumatra use jelutung for latex, ramin and balangeran for timber, and native fruits for household income. Projects combining agriculture, forestry and fisheries must balance the water needs of each activity with the need to keep peat wet.

Fish canals designed as closed loops can support incomes. However, connections to open drainage in nearby plantations can lower water tables. Careful design and community oversight are needed to keep these projects consistent with restoration goals.

For residents facing repeated floods and fire seasons, the practical issue is how to earn a living without continuing the drainage that damages their surroundings. Wet cultivation and restored water levels need to be planned together.

Buyers and lenders have choices to make

Palm oil, paper and other products associated with peat reach supermarkets and storerooms around the world. Buyers and lenders can require suppliers to stop draining peat and restore water tables, making water management part of purchasing and financing decisions.

Contracts can include commitments to zero drainage, supported by field verification and supply chains that allow products to be traced to their origins. Current technologies make those checks achievable. Certification schemes can also assess hydrology, the movement and storage of water, rather than examining forest cover alone.

Import rules can address the gap by treating peat drainage as equivalent to deforestation, because drainage destroys the ecosystem and the benefits it provides even when some trees remain. Greenhouse gas reporting by companies and governments also needs to include emissions from soil oxidation and canal water.

Banks and insurers can assess drainage risk across the businesses they finance or cover. Communities should have free, prior and informed consent before projects affect peat, meaning they can decide without pressure, before work begins, and with information about what the project involves.

Across these measures, the central task is concrete: keep more water in peat, prevent further drainage and make responsibility for damage clear. The Sumatra restoration trial shows that recovering water levels can slow subsidence and allow native trees to return, while the canal mapping shows why action must reach beyond individual plantation plots.

Key Points

• Pantau Gambut links rising flood risk to 281,253 kilometers of industrial canals across peat ecosystems in Sumatra, Kalimantan and Papua.
• Most canals are inside concessions. Nearly 4 million hectares of oil palm and about 2.5 million hectares of industrial plantation forests occupy peat.
• More than 500,000 hectares of peatlands were converted to monoculture between 2015 and 2022.
• Of 3 million hectares of peatlands burned from 2015 to 2024, more than 1.2 million hectares were inside concessions.
• Assessments put 43% of Indonesia's roughly 24 million hectares of peat at flood risk, with 6 million hectares highly exposed.
• Regional mapping found drainage in at least 65% of Southeast Asian peatlands. Dense canal networks were associated with subsidence rates around 3.2 times those of areas without drainage.
• West Kalimantan canal research estimated emissions of about 70 milligrams of carbon dioxide per square meter per day, with around 35% of dissolved carbon returning to the atmosphere.
• Legal gaps leave drainage inconsistently sanctioned, while a 2017 regulation shifts restoration responsibility to government after concession fires.
• A Sumatra trial using 257 peat dams across 4,800 hectares halved subsidence rates and supported natural regeneration of 57 native tree species in the wettest areas.
• Water table recovery, wet cultivation, stronger purchasing requirements and climate reporting that includes soil and canal emissions are proposed responses.