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Kerala’s July 2026 floods expose a river–wetland system pushed to breaking point.
Experts say the Pamba and the Vembanad-Kuttanad complex have lost most of their natural capacity to store and slow floodwaters, due to wetland reclamation, encroachments, sedimentation and tourism pressure.
Without systemic restoration, future extreme rainfall could turn the basin into a deadly trap for people and water.
The floods in Kerala this year have highlighted the huge strain that the Pamba river, the state’s third-longest, is under, along with the Vembanad-Kuttanad wetland system, experts have told Down To Earth (DTE).
For centuries, this complex hydrological landscape has operated to a natural rhythm, with water being received from rivers flowing from the Western Ghats being spread across interconnected wetlands, sediment being absorbed and transported and the movement of water towards the sea being moderated. That ecological infrastructure has been progressively altered, the experts noted.
After the floods of 2018, a warning was again sounded this July. By July 27, Alappuzha district had reported 12 deaths, 606 damaged houses and agricultural losses of more than Rs 35 crore, besides extensive damage to public infrastructure.
These figures capture the immediate human and economic cost, but not the deeper vulnerability. The more important question is not why the Pamba floods. Rivers flood. The question is why the landscape downstream has so little capacity left to absorb the flood.
The Pamba rises in Pathanamthitta district and flows through the lowlands of Alappuzha and Kottayam. It eventually reaches the Vembanad lake. Other small rivers flowing from the Western Ghats like the Achankovil, Manimala and Meenachil also reach the lake.
The lake then spreads the water across Kuttanad, the vast below-sea-level agricultural landscape, before it finally reaches the Arabian Sea.
The Vembanad is the largest lake in Kerala and the longest lake in India. The wider Vembanad-Kol wetland system, spread across the central Kerala coast, was designated a Ramsar site in 2002, recognising it as a wetland of international importance.
However, this unique hydrology is now being altered.
During extraordinary rainfall, the Pamba needs space. Its banks, side channels, wetlands, low-lying agricultural areas and connected water bodies temporarily accommodate water and slow its movement downstream.
Over decades, however, much of this landscape has been altered. Settlements have expanded into flood-prone areas. Wetlands have been reclaimed. Natural drainage channels have been narrowed or obstructed. Riverbanks have been modified. Roads and other infrastructure have fragmented the natural movement of water. Changes in sediment movement have further complicated the ability of the basin to convey and store water safely.
The Pamba cannot be restored simply by deepening isolated stretches of its channel. If the floodplain has disappeared, making a channel deeper may only move water downstream faster. The river needs room to spread during extreme events. The loss of that room is ultimately transferred to the lowlands.
Meanwhile, a major scientific assessment published in 2025 reconstructed changes in the bathymetry and floodwater-retention capacity of Vembanad. It estimated that the lake’s floodwater-retention capacity fell from about 2,617.5 million cubic metres in 1930 to just 384.7 million cubic metres in 2020. That represents an estimated 85.3 per cent loss of retention capacity.
The rain falls. The rivers rise. The floodplains fill. Vembanad receives the water. But Vembanad is shallower. Its water-spread area has declined. Its channels have been altered. Its connected wetlands have been fragmented. There is simply less room for the water.
Environmental campaigner Sreedhar Radhakrishnan warns that unless this larger relationship is addressed, the Pamba basin itself could turn into “a watery grave”. His warning goes beyond the immediate danger of river flooding. A river basin in which floodplains are occupied, wetlands are degraded and drainage routes are progressively constrained can become a trap for both water and people.
Kusumam Joseph, an environmental campaigner who has closely followed the degradation of Kerala’s water systems, argues that the debate cannot stop with declaring the lake’s carrying capacity to be exceeded. “We need detailed studies to understand how the carrying capacity of Vembanad can be increased,” she says. The point is crucial. Carrying capacity should not be treated as a static number. The objective must be to restore the ecological and hydrological functions that have been lost and thereby increase the capacity of the system to sustain livelihoods without destroying the ecosystem.
The carrying-capacity crisis is visible in another form in Vembanad’s houseboat industry. A recent assessment identified 954 houseboats through satellite imagery in December 2024, while a subsequent drone survey counted 926 in May 2025. The permissible recreational carrying capacity was put at 461 houseboats, along with limits for other categories of vessels.
The gap is extraordinary. The number of houseboats identified by satellite imagery was more than twice the stated carrying-capacity figure.
Activist Bhadran Bhaskaran says the immediate requirement is an “action plan for the Vembanad ecosystem” rather than isolated measures aimed at individual problems. That means dealing simultaneously with pollution, reclamation, sedimentation, tourism, flood management, wetland restoration and the protection of natural drainage channels.
The lake is being asked to accommodate more boats, more waste, more nutrient loading and more infrastructure while simultaneously being expected to retain floodwater. It cannot perform all these functions indefinitely without ecological consequences.
Kerala has approved an Integrated River Basin Management Plan for the Greater Pamba Basin and is moving ahead with a LiDAR survey, high-resolution digital elevation model, flood modelling and a flood-management plan. These are necessary steps, but they must lead to a larger change in policy.
The floodplain of the Pamba must be mapped and protected. Natural wetlands connected to the river must be restored wherever possible. Critical obstructions and encroachments in flood-storage areas must be identified. River restoration must include sediment management, riparian restoration and reconnection of natural channels rather than being reduced to dredging.
Vembanad needs continuous monitoring of depth, sedimentation, salinity, nutrient loads, dissolved oxygen, biodiversity and water quality. Its tourism carrying capacity must be scientifically determined and enforced. Kuttanad’s polders must be managed not merely as agricultural infrastructure but as part of a larger flood-management system.
Thottappally has an important role in draining excess water towards the sea. But a spillway cannot compensate for the destruction of a wetland. A dredger cannot replace a floodplain. A bund cannot replace an ecosystem.
Extreme rainfall will return. That is inevitable. It may arrive with greater intensity as the climate changes. The question is what happens when it does.
If the Pamba is healthy, its floodplains protected and its channels functioning naturally, part of the shock can be absorbed. If Vembanad is deeper, connected and ecologically functional, it can receive and retain more water. If Kuttanad’s wetlands remain intact, they can act as temporary storage. If the channels leading to the sea remain functional, stored water can eventually be released.
But if every component is weakened simultaneously, an extreme rainfall event becomes a disaster.
That is what Kerala witnessed in 2018. The floods of July 2026 have shown that the vulnerability remains. The deaths, damaged houses, destroyed crops and enormous infrastructure losses are not simply the consequences of heavy rain. They are also the consequences of a landscape that has progressively lost its ability to accommodate water.