Development and land reclamation around Piliyandala altered natural drainage, reduced water-retention capacity and increased flooding. The proposed solution includes drainage works, retention areas and protected wetlands. There is a much bigger lesson here for Sri Lanka: water remembers where it used to go.
Sometimes a Cabinet decision tells a much larger story than the project it is approving. The Government has approved a storm-water drainage and environmental improvement project beside the Piliyandala–Kesbewa bypass, and the explanation for why it is needed deserves attention.
Urbanisation around Piliyandala over the past decade, including construction through reclaimed paddy lands and other development, has affected natural drainage. Reclaiming low-lying land reduced the area’s ability to retain water, increased surface runoff and contributed to flood risk even during relatively modest rainfall.
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The response now includes improving drainage, rehabilitating culverts, constructing water-retention areas and protecting environmentally sensitive wetland areas. In other words, we removed some of nature’s drainage system and are now spending money trying to recreate it.
There is a lesson here considerably larger than Piliyandala. Sri Lanka’s wetlands, marshes, paddy fields, canals and floodplains are not empty land waiting for something economically useful to be placed upon them.
They are infrastructure.
They store water, slow runoff, absorb rainfall and reduce pressure on drains and canals. And they do it without sending the Treasury an invoice.
Urban development inevitably requires compromises. Cities need houses, roads, businesses, schools and transport systems, and not every piece of undeveloped land can remain untouched. But development decisions must price the environmental service being destroyed.
If reclaiming ten acres saves money today but requires taxpayers to spend hundreds of millions later on drainage, pumping and flood mitigation, the original economics may have been an illusion. Climate variability makes this still more important because increasingly intense rainfall can expose weaknesses that previously appeared manageable.
Sri Lanka therefore needs to stop treating storm-water management as something constructed after flooding begins. It is part of urban planning itself.
Every major development in a flood-sensitive area should answer a simple question before approval: where will the water go? Not where we hope it will go, but where, physically, it will go when extraordinary rain arrives.
Piliyandala’s answer is now costing money. The useful thing would be to learn the lesson before the next town makes the same mistake.
Because roads can be redirected. Water usually finds its own way home.
Be that as it may.
