Rs 2,800 crore needed to overhaul drainage link in Bengaluru: Report

BENGALURU: Following a year of multiple flooding incidents in Bengaluru, property consultancy Knight Frank has come out with a study based on existing data to find the gaps in the city’s stormwater drain infrastructure.
The two-month-long study — Bengaluru Urban Flood — was released here on Wednesday. It is their first report on the topic in India, and they believe a drainage master plan, to chalk out which up to 1.5 years may be needed, is among the solutions.
Driven by statistics from IISc and other sources, researchers estimated the city needed to construct approximately 658km of primary and secondary drains, in addition to rejuvenating the existing ones. The city currently has 842km of primary and secondary drains and the deficit was calculated based on certain parameters, including the total road length.
The capital expenditure for developing the new drainage system is estimated to be Rs 2,800 crore. About 80% of this is for developing the additional requirement, and the rest for maintaining or upgrading existing infrastructure, said V Shilpashree, the main author of the study. Shantanu Mazumder, executive director, Knight Frak Bengaluru, said the budgetary allocations and the revenue from real estate were good enough for the plan. Bengaluru has to see how other cities in India and abroad have worked out models.
Reduced length of SWDs
The study highlighted that stormwater drains that were 113.2km in length in Koramangala valley in the 1900s are now almost halved — 62.8km in 2016-17 as per the CAG 2021 report. A similar reduction for the said years was seen in the stormwater drain length in Vrishabhavathi valley where 226.3km of SWD was reduced to 111.7km. Estimating the city’s population to go up to 18 million by 2031, the report underlines the need to scale up the existing stormwater drainage system to keep up with the same.
Shilpashree said primary and secondary drains are interconnected and help transfer the excess water collected (due to rainfall) from one lake to the other. However, a lot of concrete development has damaged the inter-connectivity of lakes, thereby reducing the length of the drainage network.
Mazumder said Brand Bengaluru took a hit because of the rain and flooding issue and the same became a red flag even for apartment buyers. Whether a property is in a low-lying area or not is part of their checklist, he said, adding that things like feasibility assessment of a property will consider if it is in a catchment area.
— Inputs from Prithika Lily Correa