THE CONTEXT: On 18 May 2025, a pre-monsoon cloudburst delivered 130 mm of rain in 12 hours, pushing Bengaluru Urban’s cumulative May rainfall to 278 mm—157 percent above normal and almost one-fifth of its annual average. Twenty-plus lakes overtopped, three lives were lost, and more than 500 dwellings went under water. IMD bulletins kept the city on Orange alert even as South-Interior Karnataka shifted to Red.
WHY BENGALURU IS PRONE TO FLOODING:
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- Topographical Constraints: Bengaluru’s elevation is 900 meters, and the absence of a major river hinders natural drainage, unlike cities like Delhi (Yamuna) or Chennai (Cooum). Rainwater flows through interconnected lake systems and valleys, but encroachments and concretization have obstructed these pathways, leading to water stagnation in low-lying areas.
- Loss of Water Bodies and Ecological Degradation: The drastic reduction of Bengaluru’s lakes from 1,452 to approximately 190 directly results from urbanization. A 2016 report estimated that 80% of Bengaluru’s lakes have been lost or degraded, reducing the city’s capacity to absorb and store rainwater. Encroachment of lake beds and interconnecting valley zones, often with tacit approval from authorities, has disrupted the natural water flow.
- Outdated Drainage Infrastructure: Bengaluru’s stormwater drains, or rajakaluves, were designed for a smaller population and lower rainfall intensity. The Bruhat Bengaluru Mahanagara Palike (BBMP) has struggled to upgrade this infrastructure to meet the demands of a city with a population exceeding 12 million. Clogging of drains with solid waste further exacerbates waterlogging.
- Climate Change and Increasing Rainfall Intensity: The IMD’s data indicates a rise in rainfall intensity over recent decades, with Bengaluru receiving nearly 20% of its annual rainfall in just 20 days in May 2025. Cyclonic circulations, troughs, and pre-monsoon thundershowers, as reported by the Karnataka State Natural Disaster Monitoring Centre (KSNDMC), have intensified, overwhelming the city’s drainage capacity. Climate change amplifies these extreme weather events, necessitating adaptive urban planning.
- Poor Urban Planning and Governance: Rapid, unregulated urbanization, driven by the IT sector, has led to increased impermeable surfaces (e.g., concrete), reducing groundwater recharge and increasing surface runoff. The BBMP’s failure to enforce ecological norms and regulate construction on lake beds reflects governance deficits. Political apathy and lack of coordination among civic agencies, such as the BBMP, Bangalore Development Authority (BDA), and Bangalore Water Supply and Sewerage Board (BWSSB), compound the problem.
CURRENT SCENARIO: WORST-AFFECTED AREAS AND IMPACTS:
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- Yelahanka Zone: Recorded 103.2 mm of rainfall, with overflowing lakes flooding low-lying areas and damaging 28 homes. The Kendriya Vihar apartment complex, previously home to former President APJ Abdul Kalam, was severely inundated, requiring boat evacuations.
- Kengeri (Kote Layout): Received the highest rainfall at 132 mm, flooding 100 homes and damaging over 50 vehicles. Reverse flow in the Vrishabhavathi River led to the death of five cattle.
- Koramangala (ST Bed Layout): A perennial flood hotspot, it saw homes submerged under four feet of water, affecting 21 houses.
- Shanthinagar: The local bus depot was flooded with two feet of water, damaging buses and vehicles.
- Sai Layout (Mahadevapura): Developed by the BDA, this area saw four feet of floodwater, necessitating boat rescues for stranded residents.
GOVERNMENT RESPONSE IN BENGALURU
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- National Disaster Management Authority (NDMA) Urban Flooding Guidelines, 2010—advocates city-level Flood Management Cells, detention ponds, and real-time telemetry.
- Ministry of Housing & Urban Affairs (MoHUA) Model Building Bye-laws 2016—mandate on-site rainwater harvesting and 30 % pervious surfaces for plots > 2 000 m².
- Atal Mission for Rejuvenation and Urban Transformation 2.0 (AMRUT-2.0)—₹ 277000 cr envelope for stormwater recycling by 2026.
- Karnataka Water Security & Disaster Resilience Programme (2025-31)—₹ 5,000 cr (₹ 3,500 cr World Bank loan) using outcome-linked PforR, nine DLIs; 40 % earmarked for SWD fortification and lake reconnection.
- Bengaluru Climate Action & Resilience Plan 2023—commits to ‘net-zero drainage backlog’ by 2035 and 30 % blue-green coverage.
GLOBAL BENCHMARKS:
| City | Strategy | Transferable Lesson |
|---|---|---|
| Singapore | ABC Waters + Marina Barrage | Integrate reservoirs with recreation; pricing recycled water pays for O&M. |
| Seoul | Cheonggyecheon daylighting | Rip out flyovers to restore river corridor, cut peak flow by 30 %. |
| Wuhan (China) | Sponge City pilot | 80 % built-up area to absorb 70 % of rainwater by 2030 via permeable pavements. |
| Rotterdam | ‘Room for the River’ | Designated floodplains double as parks, balancing “safe-to-fail” philosophy. |
THE ISSUES:/THE CHALLENGES:
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- Encroachment and Illegal Construction: Builders and real estate lobbies, often with political patronage, encroach on lake beds and stormwater drains, as seen in areas like ST Bed Layout and Sai Layout.
- Inadequate Drainage Capacity: The existing stormwater drains, designed for 40–70 mm of rainfall, are overwhelmed by intensities exceeding 100 mm, as seen in May 2025.
- Solid Waste Management: Clogging of rajakaluves with plastic and debris reduces drainage efficiency, exacerbating waterlogging.
- Lack of Coordination: Overlapping jurisdictions among BBMP, BDA, BWSSB, and other agencies lead to fragmented flood management efforts.
- Climate Change Impacts: Increasing rainfall intensity and unpredictability demand adaptive infrastructure, which Bengaluru lacks.
- Public Apathy and Awareness: Citizens’ disposal of waste in drains and lack of awareness about flood risks compound the problem.
- Delayed Implementation: Legal disputes, such as those delaying drainage work in Sai Layout, and bureaucratic inertia hinder timely infrastructure upgrades.
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- Lake Governance Vacuum: Karnataka Tank Conservation and Development Authority (2014) lacks sanctioning power over urban lakes.
- Financing Constraints: Property-tax collection efficiency at 57 % limits BBMP’s debt-servicing headroom despite the World Bank line.
- Data Silos: LiDAR-based digital elevation model exists but is not embedded in master-plan zoning decisions.
THE WAY FORWARD:
| Layer | Actionable Idea | Institutional Lever | Outcome Metric |
|---|---|---|---|
| Structural (Grey + Green) | Retrofit 230 km SWD trunk with bio-swales & detention plazas: mandate “blue roofs” on IT parks > 10 000 m² | BBMP + BWSSB joint SPV; tap ₹300 cr Green Municipal Bond | Peak flow reduction ≥ 25 % by 2028 |
| Regulatory | Notify ‘Zero-Increase Runoff’ Zoning Code for new wards; make Form-2A drainage NOC compulsory before Commencement Certificate. | Directorate of Town & Country Planning | All new approvals post-2026 |
| Economic | Introduce Drainage Betterment Fee (value-capture) along Whitefield–Sarjapur corridor; cross-subsidise lake rejuvenation trust | Karnataka Urban Infrastructure Development Finance Corp. | Mobilise ₹650 cr/yr |
| Technological | Deploy 1 200 IoT rain gauges & ultrasonic flow sensors feeding a Flood Early-Warning Dashboard integrated with Karnataka State Natural Disaster Monitoring Centre | NDMA-state 50:50 cost sharing | 45-min lead time alerts; false-alarm ratio < 0.15 |
| Community & Ecosystem | Scale up “Million-Sponge” rooftop RWH campaign with CSR, linking rebates to metered recharge; restore 30 minor tanks as urban commons | Lake Development Authority & RWAs | Recharge 18 M m³ groundwater/year |
| Governance | Legislate a Bengaluru Metropolitan Drainage Authority under Article 243ZE to unify planning, O&M, and enforcement | State Legislature; Metropolitan Planning Committee | Single-window accountability |
THE CONCLUSION:
Bengaluru’s floods exemplify the transition from climate risk to governance failure. Elevation alone offers no immunity when ecological buffers crumble and institutions lag behind hydrological reality. A sponge-city cum metropolitan-governance paradigm—anchored in constitutional devolution, nature-based solutions and outcome-linked finance—can turn the ‘Silicon Plateau’ into a resilient urban watershed.
UPSC PAST YEAR QUESTION:
Q. Account for the huge flooding of million-plus cities in India, including smart ones like Hyderabad and Pune. Suggest lasting remedial measures. 2020
MAIN PRACTICE QUESTION:
Q. Despite possessing a historic lake-tank network, Bengaluru experiences severe urban floods almost every year. Analyse the multi-layered factors responsible and suggest a comprehensive strategy to convert the city into a climate-resilient ‘sponge city’.
SOURCE:
https://indianexpress.com/article/explained/bengaluru-rains-frequent-flooding-waterlogging-10019529/
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