Bengaluru: A coalition of urban researchers, hydrologists and citizen volunteers has released a detailed public assessment of Bengaluru’s stormwater drain (SWD) network, identifying systemic links between deteriorating drainage infrastructure and several urban challenges including localised flooding, increasing heat levels, water contamination and public health concerns.
The findings emerged during a day-long data analysis exercise organised at the BLR Design Centre on Church Street, where participants examined multiple datasets to understand how the city’s drainage systems interact with broader environmental and urban issues.
Data-based assessment examines city-wide concerns
The exercise was organised by OpenCity, an initiative of Bengaluru-based Oorvani Foundation, in collaboration with Mod Foundation, WELL Labs, Biome Trust and Sponge Collaborative, with support from the Bengaluru Sustainability Forum’s Small Grants Programme.
The initiative formed part of a larger programme titled Building a Resilient Bengaluru, which combines citizen participation, guided audits and educational sessions focused on urban sustainability.
According to a statement, participants used data collected through field audits and compared it with official stormwater drain maps, lake records, topographical information and land-use data.
The purpose of the exercise was to understand how urban development patterns and environmental changes are influencing Bengaluru’s stormwater infrastructure.
Study highlights connection between drains and urban heat
One of the teams involved in the analysis examined the relationship between stormwater drains and temperature patterns within the city.
Participants observed that open drains appeared to function as heat sinks, while covered or enclosed drains were associated with areas that recorded comparatively higher heat levels.
The study also found that extensive concretisation around drains may contribute to increased heat retention.
In contrast, areas with green buffers surrounding drainage systems were observed to have a moderating effect on temperatures.
Researchers suggested that vegetation and natural landscapes around drains could potentially support better thermal conditions within urban spaces.
Loss of lakes linked to flood-prone areas
Another group focused on studying natural drainage systems including lakes and tanks, and how their changing role has influenced flood patterns.
Participants noted that lakes and tanks historically acted as natural flood absorption systems by retaining excess water during rainfall events.
However, changes in land use, along with encroachment and reduction of water bodies over time, were found to have altered the natural flow of water across the city.
A significant finding highlighted by the study was that several locations currently experiencing severe flooding correspond to areas where lakes once existed.
Researchers indicated that the loss of natural water systems may have reduced the city’s capacity to manage heavy rainfall effectively.
Concerns raised over water contamination risks
One of the teams also studied intersections between stormwater drains, sewage networks and drinking water supply systems.
The analysis reportedly identified areas where close proximity between these systems could create potential risks of drinking water contamination for nearby residents.
Participants further examined conditions in informal settlements and analysed how flooding and sewage-related issues interact in vulnerable areas.
The study observed that several locations facing higher risks also had limited access to healthcare facilities.
Encroachments and urban expansion under scrutiny
Participants also assessed the impact of industrial and residential land use on water quality and overall drainage performance.
The findings suggested that both industrial activity and residential discharge may contribute to conditions affecting drain quality.
Researchers further noted that encroachments along drainage margins and increasing concretisation across urban areas are gradually reducing the city’s ability to absorb and manage rainfall.
The assessment has brought attention to the need for integrated planning involving drainage systems, environmental sustainability and urban development. The findings are expected to contribute to ongoing discussions regarding infrastructure planning and resilience measures in Bengaluru.