- A call for urgent flood resilience
The Kelani River is the lifeblood of Colombo and its suburbs. Nearly 25 per cent of Sri Lanka’s population lives within the Kelani Valley catchment, and over six million people depend on the River for their daily drinking water. Yet, last year (in 2025), this vital artery once again turned into a source of devastation, as severe flooding displaced communities and exposed deep structural failures in planning and governance.
What was once a natural floodplain capable of absorbing seasonal excess has been steadily transformed into a nonabsorbent piece of land caused by overpopulation, unregulated settlements in wetlands, and fragmented policy responses. The 2025 flood was worse than the 2016 event, reaching approximately 500 mm above previous benchmarks, the highest flood level recorded in modern times. This was not an isolated incident, but part of a recurring and intensifying pattern.
Flooding in the Kelani Valley is fundamentally a failure of integrated planning. Treating floods merely as irrigation or drainage problems is no longer viable. What is required is a holistic strategy that combines nature-based solutions (NBS), smart engineering, sound policy, and community-centred resilience.
Protecting and restoring the remaining wetlands is essential to revive nature’s own capacity to retain and slow floodwaters. This must be complemented by smart engineering interventions such as dedicated floodways, water-retention areas, and the strict enforcement of laws against floodplain encroachment, supported by revised zoning regulations. Equally critical is strengthening community resilience — ensuring early-warning systems to reach the most vulnerable, promoting community-based disaster preparedness, and adopting flood-resilient housing designs for at-risk populations.
Why was the Kelani Valley so severely affected?
Several interconnected factors converged to make the 2025 flood particularly destructive. Extreme rainfall across the Basin coincided with upstream Reservoir releases, including spill-gate openings at Reservoirs such as Maussakele, sending massive volumes of water into an already swollen Kelani River.
Climate-related risks further compounded the situation. The sea-level rise, projected to reach about 210 mm by 2050, reduces the River’s gradient near its mouth, slowing the discharge of floodwaters into the sea. During heavy rainfall, this reduced slope worsens drainage conditions, causing water to back up and inundate low-lying areas.
Urbanisation has steadily erased natural floodplains, removing critical buffers that once absorbed excess water. Geographic vulnerability adds to this risk. Studies, including those by Gihan Ranasinghe on flood hazards in the Kolonnawa Divisional Secretariat, indicate that nearly 70% of the area lies below the sea level, making it exceptionally prone to flooding.
These vulnerabilities are being amplified by climate change, turning the Kelani Valley into a high-risk zone with cascading consequences.
Climate change
Climate change is not a distant possibility; it is the future that we are already entering. Whether its impacts can be mitigated — or partially reversed — depends fundamentally on our collective behavioural change and our capacity to build climate resilience. Climate change is not merely an environmental phenomenon; it is the cumulative outcome of human lifestyles and economic policies.
For nearly five centuries, beginning with Western colonial expansion, an exploitative economic culture has shaped humanity’s relationship with nature. Colonisers treated occupied land as property to be extracted without restraint. Topography was altered, forests cleared, agriculture and mining reorganised for maximum output, and landscapes reshaped to serve imperial economies. These interventions disrupted ecological balances, altered microclimates, and permanently transformed natural systems. In contrast, indigenous societies, bound culturally and spiritually to their land, treated it as a trust rather than a commodity. Their symbiotic relationship with nature — through traditional agricultural and extractive practices — respected ecological limits and sustained environmental equilibrium.
The post-colonial era did not mark a departure from this trajectory. Instead, ecologically destructive development models, inherited economic thinking, and a globalised consumerist culture intensified environmental degradation. Large-scale deforestation, uncontrolled urbanisation, indiscriminate resource extraction, and the use-and-throw ethos of mass consumption led to mounting waste, habitat loss, and rising carbon emissions. These processes collectively accelerated global warming, raising ambient temperatures and destabilising climate systems. As a result, local weather patterns have become increasingly erratic, manifesting as torrential rainfall, floods, droughts, forest fires, landslides, rising sea levels, and extreme heat events.
In the 21 Century, this crisis has deepened into a dangerous convergence of post-colonial economic paradigms, irresponsible human behaviour, and entrenched consumerism, compounded by oligarchic interests that shape political decisions in their favour. This toxic combination continues to undermine ecological integrity and imperil human life.
The extreme and unpredictable climate phenomena that we now experience are not anomalies; they are the logical outcome of centuries of unsustainable economic policies, social behaviour, and an atomised materialist culture. Addressing this crisis requires more than science-based engineering or technological fixes. It demands a holistic transformation encompassing lifestyle changes, economic restructuring, and political decision-making rooted in ecological responsibility and long-term thinking.
Central to this transformation is cultivating a genuine sense of stewardship among citizens — a recognition of land as a shared trust rather than a resource for unchecked exploitation. People must be empowered and encouraged to protect and enhance the ecological and environmental value of their surroundings. In this regard, religion, culture, and social institutions play a critical role in fostering ethical frameworks that emphasise harmony with nature and challenge the individualistic, materialistic, and hedonistic values that erode both the society and the environment. Reviving lost value systems and rebuilding socio-ecologically responsible cultures are essential to reconnect people with their land and inspire collective responsibility.
The devastation witnessed after Cyclone Ditwah must not be dismissed as a freak event. It is a warning — an early manifestation of an unraveling future in a country that the global scientific community has long identified as highly vulnerable to climate change. Policymakers and citizens alike must therefore recognise the urgency of reforming lifestyles and socio-economic policies. Only through decisive, integrated action can we hope to build a climate-resilient nation capable of withstanding the challenges that lie ahead.
The human and socio-economic cost
Floods impose a disproportionate burden on poor and marginalised communities. Each event strips families of homes, life savings, essential documents, livelihoods, education, and access to opportunity — pushing them deeper into poverty with every recurrence.
This is not merely a humanitarian issue; it carries serious socio-political implications. The persistent neglect of flood-affected communities undermines national development and concentrates deprivation in the heart of Colombo. Apathy towards their plight deepens vulnerability, erodes social stability, and denies these citizens a fair share of development dividends. This is an urgent national imperative.
Immediate responses while long-term solutions evolve
Comprehensive flood resilience requires time and investment. However, several immediate measures can be implemented using existing institutional capacities, particularly during post-flood recovery phases.
- Empower Local Authorities by enabling regional Pradeshiya Sabhas, Municipal and Urban Councils to:
- Maintain and dredge regional drainage systems to ensure the smooth storm-water flow.
- Oversee the operation of irrigation sluice gates to prevent unnecessary water accumulation.
- Strictly enforce waterway reservations and remove unauthorised structures.
- Enforce plot-coverage and building regulations.
- Identify squatters occupying flood reservations for relocation.
- Introduce regulations requiring green roofs and rainwater harvesting for buildings with roof areas exceeding 100 square metres to reduce surface runoff.
- Strengthen solid-waste management and prevent illegal dumping.
- Coordinate with stakeholder agencies and law enforcement to ensure routine preventive maintenance and emergency readiness.
- Establish effective public warning systems and pre-identified temporary relocation centres.
- Strengthen inter-agency coordination
Institutions such as the Urban Development Authority, the Central Environmental Authority, the Road Development Authority, and the Land Reclamation and Development Corporation must work in close coordination with the Local Authorities to ensure timely and coherent responses.
- Strategic State intervention
The State should consider decisive land-use and housing reforms:
- Declare perennially flooding areas as zero-value zones where buying, selling, or building is prohibited, while providing alternative housing and vesting such land with the State.
- Establish a secondary buffer zone — approximately 300 mm above the lowest flood level — where development is restricted and gradual, supported relocation is encouraged.
- Promote low-rise housing (ground plus four floors) with the ground floors reserved for parking and flood-emergency use.
- Develop intermediate-rise housing (ground plus eight floors) with green roofs that double as community spaces and rainwater-harvesting systems.
- Improve existing regulations incorporating climate change mitigation practices.
- Appoint a special steering committee to improve coordination, resettlement, and post-flood recovery.
- Mobilising community-based organisations (CBOs)
CBOs — including mosque federations, temples, and voluntary organisations that played a critical role during the immediate aftermath — should be integrated into a structured disaster-response framework. They can:
- Improve climate-change literacy and community resilience.
- Support the planned relocation of families from high-risk flood zones.
- Coordinate among themselves and with State agencies to avoid duplication and improve efficiency.
- Partner with corporate entities to channel corporate social responsibility funds towards sustainable recovery.
A defining choice
The Kelani River floods are a warning. Without integrated planning, climate-responsive policy, and collective behaviour change, floods will continue to deepen inequality and undermine Colombo’s resilience. The choice is clear: continue reacting to disasters — or act decisively now to restore nature, strengthen infrastructure, and protect communities before the next flood arrives.
The writer is an architect and sustainability consultant
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The views and opinions expressed in this column are those of the author, and do not necessarily reflect those of this publication