Intro (Micro Notes):
• Urban flooding = accumulation of water in urban areas due to rainfall, poor drainage, infrastructure failure.
• Cities like Hyderabad (2020), Pune (2019), Chennai (2015), Bengaluru (2022) faced massive floods despite being ‘smart cities’.
Causes of Urban Flooding in Million-Plus Cities:
1. Unplanned Urbanization:
• 35% urban expansion (2001–2021) lacked drainage & zoning norms.
• Hyderabad: Encroachments on Musi river floodplains.
2. Drainage System Collapse:
• 70% Indian cities have outdated or under-capacity drainage systems.
• Pune: Blocked nalas & concrete surfacing prevent natural runoff.
3. Encroachment of Water Bodies:
• 30% of lakes in Bengaluru lost to real estate.
• Chennai: Pallikaranai marshland encroached, worsened 2015 floods.
4. Extreme Rainfall Events (Climate Change):
• IMD: 54% rise in extreme rainfall events in urban India (2000–2020).
• Hyderabad 2020: 300+ mm in 24 hours.
5. Poor Solid Waste Management:
• Drains choked with plastic waste in Delhi, Mumbai, etc.
6. Topographical Constraints:
• Low-lying coastal & riverine cities vulnerable – e.g., Mumbai, Kolkata.
Lasting Remedial Measures:
1. Urban Water-Sensitive Planning:
• GIS mapping, watershed zoning, floodplain regulation.
2. Restoration of Natural Drains & Wetlands:
• Rejuvenate urban lakes, stormwater channels – e.g., Hyderabad’s lake revival project.
3. Sponge City Model:
• Permeable pavements, rain gardens – adopted in China & proposed in Delhi Master Plan 2041.
4. Upgraded Drainage Infrastructure:
• Smart Stormwater Systems – Pune Smart City Mission pilot.
5. Legislation & Community Participation:
• Strengthen NGT mandates, involve local RWAs in flood preparedness.
Conclusion:
• Urban floods are human-made disasters rooted in planning failures.
• Integrated urban flood management is critical to make Indian cities climate-resilient.
