Dev Diaries SL

#SLFloods: Thinking about Urban Flooding before it floods again


When Colombo is flooded our economy is flooded. So lets think about urban flooding before it floods again.

Following months of prolonged heat, finally made it seem like the prayers had been answered in May. However the optimism was short lived as heavy rainfall resulted in floods throughout the island. 22 of 25 districts were affected. Out of the various aspects to be addressed in this regard such as, government commitment, effectiveness of the disaster management authority, post flood reconciliation, collective action of the public, I will focus my writing on the concept of Urban Flooding.

Colombo is the main hub of Sri Lanka and is the most populated city. It accounts to all the main administrative decision making bodies and the lion’s share of economic activity. Ironically it is also one of the most vulnerable cities to flood related damages. However, during the last regime, we saw that flooding in the heart of Colombo – Fort, Pettah, Colombo 7 especially – was addressed, or rather improved compared to its previous state. The fragility and vulnerability of the city however is far from addressed as we saw in May. The localities prone to flooding has shifted from the ‘Urban’ to the ‘Sub Urban’ areas of Colombo. In general the reasons for this are Urbanization, demographics and Climate Change. Colombo has grown beyond its Municipal limits.

‘Urban Flooding’ is caused by prolonged rainfall which overwhelms the capacity of the city’s drainage system. Poor drainage systems are coupled by factors like unplanned garbage disposal sites and of course negligence of the average individual. The end result is the hindrance to the functionality of the city and its activities. Despite our firsthand experience ‘urban flooding’ is not unique to Sri Lanka; we saw thousands displaced in recent flooding in Chennai.

In its nature itself ‘Urban Flooding’ is a tough process to handle, mainly due to its unpredictability and the time needed for it to occur. Due to this reason it is understood that there is nothing that can be done ‘during’ the rainy days. But rather the actions should be taken before hand; preventive action. Disaster prevention requires the necessary expertise and commitment. The government has to take the necessary actions and utilize the needed physical and human assets to address this. On a positive note it was seen that the previous regime had taken certain steps to address flooding in Colombo, mainly under the ministry of urban development. The fix however has been applied only to the ‘obvious’ locations which has changed the localities that are affected by floods within the city.

Upon discussions with affected individuals it was revealed that one of the main reasons for the intensification of the effects of flooding was the human alterations to the natural drainage routes. Further, it was evident that the established sewers and drains could not handle large quantities of water. High proportion of tarmac and paved surfaces increases the probability of urban flooding. This is mainly because it limits water infiltration. Natural drainage systems are often altered during urbanization and this reduces the capacity of the system to store excess water.

When considering the suburban areas of Colombo, the most vulnerable areas are located along the banks of the Kelani River; the northern limit of the municipal area. Flooding in May portrayed probably the worst case scenario of river flooding experienced by the suburbs of Colombo. The unpredictability of floods was highlighted during the period as both the authorities and the civilians underestimated the rise in water levels in the river. This resulted in the breakdown of vital networks such as the transportation links. These are factors to considered for future disaster prevention and management.

Authorities should consider this a warning sign. Even though there was a high focus on Urban Flooding in the heart of Colombo, now the effects have shifted to the suburbs. Climate change has a direct link to this as in the coming years it would be a common occurrence that we would experience prolonged days of heat with heavy rains within shorter timespans relative to the past. The Irrigation Department has to think of coping mechanisms regarding the areas surrounding the Kelani River.

Apart from the authorities, the general public too has a responsibility upon them to adjust to the new natural changes. There is more to such a natural disaster than giving donations to the affected communities. Processes and policies that would minimize the effects should be funded and aided and these should be done during times when “floods” don’t occupy the headlines, hence it requires real commitment. Floods might not be entirely preventable. But the impact of urban flooding can be reduced.

The Island Under Water –

As the bad weather persisted, the tri forces were deployed again today (May 18) to disaster affected areas, to provide relief and assistance. The Sri Lanka Air Force (SLAF) conducted reconnaissance missions to support ongoing relief operations by flying over disaster affected areas, to assess da

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