Flooding in urban areas is an emerging climate-induced disaster. Discuss the causes of this disaster.…

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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.

Ghissu Editorial · Accepted Answer

Urban floods arise when more extreme rain meets sealed land, lost lakes and choked drains, as Mumbai in 2005 and Chennai in 2015 showed. India responds through NDMA's 2010 guidelines, AMRUT, the Urban Flood Risk Management Programme and city flood-warning systems.

**Introduction**

Urban flooding is the inundation of a city when intense rain overwhelms drains squeezed by concrete and lost water bodies; NDMA counts 5,161 urban local bodies as prone to it (2023).

**Causes of Urban Flooding**

1. **Climate-intensified rain**: Widespread extreme rain events over central India rose threefold between 1950 and 2015 (Roxy Koll et al., 2017).
2. **Sealed land and lost lakes**: Delhi's built-up area rose from 20% in 1985 to 52% in 2018 (NIDM, 2025), and NDMA estimates sealing can raise flood peaks 1.8 to 8 times.
3. **Choked drains and encroachment**: Mumbai's drains were built for about 25 mm an hour, waste clogs them, and floodplains are built over.

SKETCH: flow | How Rain Becomes a Flood
- Extreme rainfall
- Sealed surfaces
- Runoff surge
- Choked drains
- Waterlogged city

**Two Major Urban Floods in India**

1. **Mumbai, July 2005**: 944 mm of rain in 24 hours at Santacruz, an encroached Mithi river and a high tide drowned the city; over 1,000 died across Maharashtra.
2. **Chennai, 2015**: Record north-east monsoon rain and Chembarambakkam releases into the Adyar flooded a city built over lakes and the Pallikaranai marsh, killing over 400 in Tamil Nadu.

**Policies and Frameworks for Urban Floods**

1. **NDMA Guidelines (2010)**: Rain-gauge networks, ward-level flood maps and watershed-based drain design.
2. **Missions and finance**: AMRUT drainage works, the CPHEEO drainage manual (2019) and the Urban Flood Risk Management Programme (2023) for seven metros.
3. **Warning and law**: C-FLOWS Chennai, IFLOWS-Mumbai and urban disaster authorities under the DM (Amendment) Act, 2025.

**Way Forward**

1. **Sponge-city design**: Restore lakes and use permeable surfaces.

**Conclusion**

Urban floods are climate-triggered but city-made; planning with water, not against it, is the lasting answer.

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.

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