The Urban reality

Flooding after every downpour, the downside of mindless urbanization:

by Rukshana Rizwie

The catastrophic flooding in Chennai which inundated its international airport for days and left thousands homeless, is a stark reminder that the built environment doesn’t do well in the rain.

- www.ecobusiness.com

Similarly, shorter spells of rain, intense downpours and a little over two inches of rain overnight can bring Colombo to a crippling standstill. Urban flooding in Colombo is chronic and costly, experts opine. While the underlying causes continues to be blatantly ignored.

“The fact remains that mindless development and urbanisation over the last few decades including the reclaiming of lowlands and choking of storm water drains as well as other avenues for water flow is conducive to floods,” explained Dr Rangajeewa Rathnayake, who heads the Department of Town & Country Planning at the University of Moratuwa.

Speaking of the current context, Dr Rathnayake said that it was evident the authorities had abandoned the concept of storm water drains – an essential instrument in fighting floods when it came to construction and urbanisation.

“Storm water drains in Colombo have been in existence for decades, however we’ve observed that their linkage to water bodies and topographical data of the water flow are rarely seen as part of the whole system,” he said. “As a result of such poor urban planning the use of the system is ignored and man-made systems are of no match.”

Excessive construction he explained has led to poor recharge of groundwater aquifers and blocking of natural drainage systems. Storm water drainage systems on the other hand are either clogged or closed off.

Drainage channels

“Freehold land space or water bodies which was once used to retain rainwater are now multi-structured buildings or recreational sites,” he said citing that such water bodies and lakes has a natural flood discharge channel which can drain the spillover. “If all such water retention spaces are filled, water overflows.”

He further said that water log data are not deemed important since many constructors are compelled to complete projects within a short span of time before funds run dry.

“At present we do not have standards or regulations to prevent the blocking of such drainage channels,” he said. “Even if there are any, its not being followed.” Dr. Rathnayake explained that there needs to be increased awareness among the general public about how they are continuously contributing to the problem. “Even when it comes to building a wall, there is a reason why you require the council’s approval. A wall is a permanent structure which blocks water flow.”

He referred to housing schemes citing of how so many of them are quickly deluged in water after a short spell of rain.

World Bank Metro Colombo Urban Development Project

The World Bank embarked on an ambitious project three years ago funding it to a tune of USD 213 million in a bid to reduce flooding in the Colombo basin and improve local infrastructure to mitigate the floods.

The team leader of the project who is currently in Sri Lanka in an email said that the project has completed “demonstrative initiatives through local authorities such as the rehabilitation of existing roads, drainage and canal systems to channel out excessive water from the Colombo basin,” adding that “these short term measures have begun to show benefits in reducing of floods.”

Based on the World Bank report, even though the Colombo Metropolitan Region covers only about 6 percent of the country’s total land area and is home to 28 percent of its population, it accounts for almost 50 percent of the national GDP and 80 percent of industrial value.

Clogged canals

Elaborating on the floods situation, they added that the drainage system is obsolete and needs to be improved and expanded while the canals are clogged with garbage and encroachments, the wetlands, which play a very important role in maintaining this balance, have been either filled or not managed adequately - reducing its ability to store excess water.

Climate change has also led to shifts in the rainfall patterns. To address the issue of flooding in Colombo would require comprehensive approach and long term measures.

Asian Development Bank gives While in Paris for the COP21, the Asian Development Bank has agreed to fund USD 435 million as part of a USD 675 million project to construct two new reservoirs and 260 kilometres of canals that will upgrade the existing reservoirs across the country.

The extra water will also be funnelled into existing hydro-power dams to generate 250 MW of new electricity.

This particular project is expected to commence next year in February and be completed by 2024.