Revision summary
Cities flood because lakes, nallahs, and soils were sealed and encroached. Hyderabad 2020 and Pune show Smart projects without sponge hydrology. Design storms are outdated for a warmer, cloudburst climate. Lasting fixes are legal floodplains, bigger drains, permeable streets, and waste control. Dashboards do not replace tanks.
Model answer
Copper italics in this answer — like this — are the key facts. Each one is unpacked in the Facts & figures rail.
Introduction
Indian million-plus cities flood because rain now hits a sealed basin that used to be a lake-and-nallah sponge. Hyderabad 2020 and repeated Pune floods show that a Smart City dashboard does not raise a riverbed or unclog a drain.
Body
Why the water has nowhere to go
- Lakes and tanks — Musi floodplains and lesser cheruvus in Hyderabad, Mula–Mutha corridors in Pune — were built over for layout plots and IT parks.
- Storm drains are sized for an older rainfall intensity; cloudbursts and a warmer atmosphere now exceed that design.
- Hard paving kills infiltration; every parking lot is a tributary.
- Solid waste and construction debris choke nallahs; the flood is often a blocked drain, not only a big river.
- Upstream dams and hard embankments can worsen peak timing when gates open into a city that has no floodplain left.
Smart is not sponge
- Hyderabad’s 2020 Musi–nallah disaster and Pune’s riverfront-plus-rain events hit cities with cameras, GIS, and Smart Mission projects. Sensors without lake restoration are cosmetics.
- Chennai 2015, Bengaluru layout floods, and Mumbai’s Mithi are the same family: million-city hydrology ignored in master plans.
Lasting remedies
- Legal lake and floodplain buffers, demolition of obvious encroachment, and a public drain cadastre — not seasonal desilting theatre.
- Sponge design: permeable streets, rooftop rain, recharge wells, and restored tanks as in a serious Water-Sensitive Urban Design code.
- Stop building in riverbeds; revise development control rules and make the disaster management plan bind the municipal corporation, not only NDMA PDFs.
- Waste segregation and nallah trash racks; treat solid waste as flood infrastructure.
- Upstream watershed, early warning, and insurance last; the first fix is to give rain a legal path to the river.
- Finance: AMRUT 2.0, Smart City funds, and State disaster windows should buy culverts and tanks, not only LED poles.
Flow diagram
flowchart TD ENC[Lake nallah encroachment] --> F[Urban flood] PAV[Paving waste] --> F RAIN[Cloudburst] --> F SP[Sponge restoration] --> FIX[Lasting remedy] LAW[Floodplain law] --> FIX
Conclusion
Million cities flood because they paved the sponge and pinched the Musi and Mula–Mutha. Hyderabad 2020 and Pune prove Smart branding is not hydrology. Lasting remedy is floodplain law, drain capacity, and sponge streets — enforced every dry season, not only after the next cloudburst.
Quick related
Students also ask
-
Highlight the Central Asian and Greco Bactrian elements in the Gandhara art.
Next question on this syllabus topic (2019 · Q1). View answer →
-
Is climate the only villain?
Heavier rain is real. Encroachment and paving decide whether that rain becomes a disaster.
-
Can pumping save a million city?
Pumps are a last resort. Lasting safety is space for water in the master plan.
Same topic · past papers
UPSC has asked this before
These previous-year questions sit on the same topic. Open one to practise the earlier ask.
More from this topic
Q11 · UPSC Mains 2026 · GS I · 15 marks · Solution
Vijayanagara architecture exemplifies the amalgamation of past traditions with contemporary practices. Elucidate with examples.
Indian Heritage and Culture
• The Vijayanagara architectural style (14th–17th centuries) brilliantly synthesized classical Dravidian traditions with contemporary Deccan innovations. • It preserved grand spatial layouts, towering gopurams, and enclosed prakaras inspired by earlier Chola and Pandya idioms. • Sacred centers maintained canonical sanctum alignments while expanding peripheral structures to encourage greater public participation. • Secular buildings, such as the Lotus Mahal and Elephant Stables, integrated Islamic arched vaults and domes. • Builders utilized locally available hard granite, shifting ornamentation techniques toward bold, deep-relief stone carving. • Innovative structural typologies included multi-shafted composite pillars featuring rearing yalis, horse riders, and hanging brackets. • The Vittalaswami Temple at Hampi showcased pioneering acoustic engineering through famous resonant musical pillars.
Q1 · UPSC Mains 2026 · GS I · 10 marks · Solution
Analyze the importance of Ashokan inscriptions for reconstructing Mauryan history.
Indian Heritage and Culture
Ashokan inscriptions serve as the bedrock for reconstructing Mauryan history by offering authentic, contemporaneous evidence directly from the emperor. Written primarily in Brahmi, Kharosthi, Aramaic, and Greek scripts, they illuminate Ashoka's administrative reach, socio-religious policies, and the moral framework of Dhamma. Distributed across the Indian subcontinent and beyond, these edicts document spatial boundaries, diplomatic ties with Hellenistic kingdoms, and the socio-economic milieu. They bridge the gap between literary accounts and archaeological finds, providing an invaluable indigenous chronology.
Q15 · UPSC Mains 2025 · GS I · 15 marks · Solution
How can Artificial Intelligence (AI) and drones be effectively used along with GIS and RS techniques in locational and areal planning?
Indian Heritage and Culture
Remote sensing supplies pictures of land and water; GIS stores them with administrative boundaries. Drones add cheap, repeatable local maps for disasters, utilities and village layouts. Artificial intelligence classifies pixels and can forecast flood, heat or sprawl on that GIS base. Indian platforms such as Bhuvan and Gati Shakti already try to combine these tools. Planning still needs ground checks and a public purpose, or the map only watches the poor. The four tools are a chain: locate, refresh, read, then choose the public use.