Better Building Codes Could Mitigate Flash Flooding

Flooding problems that occasionally strike the western plains of Sri Lanka could be made even worse if building codes aren’t changed. That was the conclusion expressed in mid-November of 2010 by Ananda Mallawatantri, who is the assistant resident representative of the UN Development Programme (UNDP).

Southern and western Sri Lanka were hit by heavy rains and flooding in May, killing 22 people, damaging 900 homes, and affecting 672,000 people in total. Then in November, the capital city of Colombo experienced flooding as a result of unusually heavy rains, and more than 315,000 people were marooned. Some of the blame for damage in both cases was laid on the fact that drainage and channel systems have experienced blockages or have literally had buildings erected on them.

The government’s Disaster Management Center has cooperated with the UNDP in carrying out a major cleanup project both in Colombo and in its outlying areas. In fact, there have been two such projects, one completed in 2006 and another in 2010. These efforts were combined with another cleanup operation aimed at preventing dengue fever. While none of this work prevented the canals of Colombo from filling rapidly during the November rains, making many roads impassable, they did provide enough reduction in bottlenecks that the floods were able to recede more quickly.

It has been recognized that these periods of flooding come at regular intervals, in May and November of each year, and the incidence of severe urban flooding is increasing. In 2010 alone, nearly a million people were affected by such floods. While almost $1 million has been allocated by the government for compensation and relief work, the need for such compensation could potentially be reduced by taking preventative measures. And one of those measures is the establishment of building codes preventing the blockage of drainage channels or the building of edifices over them.