Will Bengaluru Ditch Basements To Fight Floods? Experts Weigh In
Bengaluru’s Flooded Future: A Basement Ban on the Horizon?
Bengaluru, India’s bustling tech hub, has been grappling with severe flooding in recent days. The downpours have underscored the city’s vulnerability to waterlogging, prompting a new debate: should basements be banned in flood-prone areas?
A Sound Idea, But at What Cost?
After two men tragically died while pumping water from a flooded basement in BTM Layout, Deputy Chief Minister D.K. Shivakumar announced the state government is considering a ban on basement parking in low-lying and flood-prone areas.
“I am taking a policy decision that wherever there is a low-lying area, we will not allow underground parking facilities in future. We will allow them to build parking spaces at a higher level,” he told reporters.
While the idea of eliminating basements to mitigate flood risks seems logical, experts raise concerns about the potential impact on construction costs and design.
The High Price Tag of Basement-Free Buildings
Abhay Gupta, a structural consultant, explains that basements often offer cost savings during construction. Excavation costs are already factored in, and the space is utilized for parking, eliminating the need for soil refilling. Without basements, developers must refill excavated areas, adding to expenses. Additionally, basements can provide more parking capacity due to their larger footprint, compared to ground-level parking.
Sarang Kulkarni, Managing Director of Descon Ventures, adds that a single basement can offer the parking capacity equivalent to 2.5 to 3 floor levels.
Design Challenges and FSI Constraints
However, eliminating basements may not significantly reduce construction depth. Foundations often still require digging to around 6 meters, depending on soil conditions and structural requirements. This could lead to higher overall construction costs.
Furthermore, developers might face challenges in utilizing the full Floor Space Index (FSI), a key urban planning metric that determines the maximum permissible built-up area on a plot. This could lead to suboptimal land use, especially in areas with height restrictions.
In contrast, cities like Hyderabad, with more relaxed FSI limits, allow for greater design flexibility. Developers there often allocate the ground and first floors for retail, the second for parking, and the upper floors for office use, creating more efficient mixed-use developments.
Finding Alternatives: Podium Construction and Beyond
Experts suggest podium-level construction as a potential solution. This involves building a raised concrete podium with a sealed, box-like structure beneath it for parking. Ramps can connect this podium to the basement, preventing groundwater seepage while preserving the advantages of underground parking.
The debate surrounding basements in Bengaluru highlights the complex trade-offs involved in urban development. Finding solutions that balance flood resilience, affordability, and design practicality will be crucial for the city’s future.
