The flash floods of July 2016 that left parts of the city under water seem to have had little impact on civic agencies in terms of ensuring that mistakes are not repeated.
The poor identification of vulnerable low-lying areas was one of the many factors that led to the floods. However, few measures have been taken to correct this.
The Bruhat Bengaluru Mahanagara Palike (BBMP) is still working on fixing flood-prone zones based on outdated information — they are using maps that were proven to be outdated a year ago to identify vulnerable zones.
After the 2016 floods in the south-east of the city, the Karnataka State Natural Disaster Monitoring Centre (KSNDMC) was equipped with higher-resolution contour maps of the city to aid better identification of flood vulnerability. However, even eight months after they were given these maps, KSNDMC has not re-assessed the flood vulnerability of the city.
The BBMP would have been better equipped to draw up its plans with fresh data.
Flood-prone areas
The disaster-monitoring centre was working on a 10-metre contour map of the city, which meant that only areas with a gradient difference of 32 ft and more were seen on the map.
Based on this contour map, KSNDMC identified 178 flood-prone areas. But, the Bangalore Development Authority shared with KSNDMC a 2-metre contour map, which can identify a low-lying area even at a gradient difference of 6.5 ft, thereby providing more clarity on water flow and flood vulnerabilities. Based on this revised map, sources say, the number of flood-prone areas in the city, presently identified at 178, would double.
G.S. Srinivasa Reddy, director, KSNDMC, said that while the centre had started using 2-metre contour maps for rain measures, they were yet to run the flood-vulnerability model on the new maps. He added that the exercise would be taken up soon. However, with predictions of an early onset of the monsoon, there are fears that the city will be left vulnerable once more.
Best tool lying unused
V. Ravichandar, member, BBMP Restructuring Committee, said it was ironic that the best tools available were not yet put to use to prevent another flood in the city. “The city deserves better. Now, even if KSNDMC identifies the flood-prone areas using the 2-metre contour maps, it will be too late to take corrective measures before the monsoon,” he said.
K. Sidde Gowda, Chief Engineer, Storm Water Drains, BBMP, said that apart from 178 flood-prone areas, they have identified more vulnerable spots based on inputs from ground staff working with the civic body and traffic police, taking the total to 222. “We have taken several corrective measures at these spots. But after trying to fix them, we have discovered more such spots down stream of the water flow. We are trying to work on those now,” he said.
