When water came knocking: The state of storm water drains of Bangalore

Storm water drain near Kormangala clogged with filth

Problems with the storm water drains needs urgent attention before the next big flood

Bengaluru, the landlocked capital of Karnataka has to depend on a system of storm water drains (SWD's) or rajakaluves both natural and man-made to discharge rain water. Unfortunately, most of these drains are encroached and have multiple floors of concrete over them. Added to this is the presence of large sewer pipes which run alongside the SWD's eventually obstructing its flow. Analysts point out these as potential factors that can lead to massive floods and lethal diseases.

The ignored past
“During rains, the swell was at Nagashettihalli lake, not our homes,” said Rayappa a second generation laundry worker pointing at the tall walls of Antariksh Bhavan, the headquarters of the Indian Space Research Organization near his dwelling in Bangalore.

Rayappa could identify the depressions and tracks which led to the now dried up lake. Quite a few times, Rayappa ended up in a sad gaze at the lost lake, for him, it was the memories of his childhood, but for the city of Bangalore, these are warning signs.

How it was and why it is 

Topographically, the city has four storm-water catchment valleys namely Vrishabhavathi Valley around Rajarajeshwari Nagar, Challaghatta Valley near Ejipura, Hebbal Valley and Koramangala-Madiwala Valley carry the water from the city’s upland to a closed network of lakes. But, the exponential growth of this city has forced concrete poops over these very same areas and has choked its drain system. This was evident from the fact that the last major downpour towards the end of November 2013 had flooded the Koramangala-Madiwala valley which domenod areas around Bannerghatta road into large scale water-logging.

A map of the storm water drain system of Bangalore city (Source: BBMP)

Apart from the encroachments, these storm-water drains are vacated from their purpose by the ill-designed sewage network of this metropolis. A majority of SWD's are mistaken to be sewage channels around the city, spicing up this issue is the presence of solid waste which obstructs the flow of water and thereby creating islands of garbage. These piles of garbage and sewage channels cause redirection and blockage of SWD's thereby creating infectious floods.

Act now
To save the city from another November rain, it is necessary to reclaim these lost SWDs but not in the current demolition format. Instead, there should be an efficient body to plan and redraw the SWD network of Bangalore in accordance with practicality and the same should be executed at the same pace till completion. And also the authorities should have a re-look at the sewage network and its convolution with the SWDs.