4 November: urban flooding
Wednesday 4 November 2026
GS Paper 3 · 250 words · 15 marks
Flooding in urban areas is an emerging climate-induced disaster. Discuss the causes of this disaster. Mention the features of two such major floods in the last two decades in India. Describe the policies and frameworks in India that aim at tackling such floods.
(UPSC Mains 2024, GS Paper 3, Q18)
You have eleven minutes. Write your answer before you read anything below.
Open only after you have written
How to approach this question
The directive. There are three tasks. Discuss the causes, mention the features of two floods, and describe the policies. Give each its own heading so the examiner can find it. Keep the introduction short, because the word budget is tight.
A shape that works in 250 words.
| Part | Words | What to write |
|---|---|---|
| Introduction | 20 | One line on why urban floods are rising |
| Causes | 60 | Four or five, one line each |
| Two floods | 75 | Date, place and two or three features each |
| Policies | 70 | Three or four named frameworks |
| Conclusion | 25 | A gap in policy, and a fix |
Material you can use.
| Flood | Features |
|---|---|
| Mumbai, 26 July 2005 | 944 mm of rain at Santacruz in 24 hours. The Mithi river, narrowed by building, overflowed. Drains were designed for about 25 mm an hour |
| Chennai, December 2015 | Extreme rain filled the reservoirs. Water released from Chembarambakkam lake flooded areas along the Adyar. Building on lakes and the Pallikaranai marsh removed storage |
| Policy | What it does |
|---|---|
| NDMA Guidelines on Management of Urban Flooding (2010) | First national guidelines treating urban floods apart from river floods |
| AMRUT (2015) | Funds storm water drainage in cities |
| iFLOWS-Mumbai (2020) | Flood warning from rainfall, tide and river data |
| Brihanmumbai Storm Water Disposal System (BRIMSTOWAD) | Resizes Mumbai's drains for 50 mm an hour |
| Disaster Management (Amendment) Act, 2025 | Lets states set up Urban Disaster Management Authorities, chaired by the municipal commissioner |
Mistakes to avoid.
| Mistake | What to do instead |
|---|---|
| A long introduction on climate change | One line, then causes |
| Floods named with no features | Date, rainfall, and what failed |
| A flood from before 2004 | The question asks for the last two decades |
A model answer
Urban floods are rising as heavier bursts of rain fall on cities that have built over their drainage.
Causes.
- Warming brings more short, intense bursts of rain.
- Concrete stops water soaking in, so more runs off.
- Lakes, wetlands and stream beds have been built over.
- Old drains are too small. Mumbai's were designed for about 25 mm an hour.
- Solid waste chokes drains.
- In coastal cities, high tide blocks outflow.
Two major floods.
- Mumbai, 26 July 2005. Santacruz recorded 944 mm of rain in 24 hours. The Mithi river, narrowed by construction, overflowed. Rail and road links stopped for days.
- Chennai, December 2015. Extreme rain filled the reservoirs. Water released from Chembarambakkam lake flooded areas along the Adyar. Building on lakes and the Pallikaranai marsh had removed natural storage. The airport closed for several days.
Policies and frameworks.
- The NDMA's Guidelines on Management of Urban Flooding (2010) were the first to treat urban floods apart from river floods. They call for detailed contour maps and drains sized to local rainfall.
- AMRUT (2015) funds storm water drainage.
- iFLOWS-Mumbai (2020) issues flood warnings from rainfall, tide and river data.
- Mumbai's BRIMSTOWAD upgrade, sped up after 2005, resizes drains for 50 mm an hour.
- The Disaster Management (Amendment) Act, 2025 lets states set up Urban Disaster Management Authorities, chaired by the municipal commissioner.
Most of these act on drains. Cities should also protect lakes, wetlands and flood plains in their master plans, and send residents ward-level warnings.
Word count: 244.
| Where | What earns credit |
|---|---|
| Opening | One line, so the words go to the three tasks |
| Body | Each flood has a date, a figure and what failed |
| Conclusion | Names the gap in current policy |