What are the environmental implications of the reclamation of water bodies into urban land use ? Explain…

Question

What are the environmental implications of the reclamation of water bodies into urban land use ? Explain with examples.

Ghissu Editorial · Accepted Answer

Reclaiming urban water bodies removes a city's natural flood storage, groundwater recharge, sewage treatment and cooling, causing floods, water scarcity and biodiversity loss. Velachery, built on a lake bed, went under in the 2015 Chennai floods as the shrunken Pallikaranai marsh could no longer absorb the overflow.

**Introduction**

Urban lakes, tanks and marshes are a city's natural sponges. Filling them for housing, roads or depots removes flood storage, groundwater recharge and cooling at once, and they are usually the first land a growing city reclaims.

**Hydrological Implications: Floods and Water Scarcity**

SKETCH: flow | From Lake to Flood
- Lake or marsh filled
- Concrete surface
- Runoff rises, recharge falls
- Floods and water scarcity

1. **Urban flooding**: In the 2015 Chennai floods, Velachery, built on a lake bed, went under, and the shrunken Pallikaranai marsh could no longer absorb the overflow.
2. **Blocked drainage**: Bengaluru's 2022 Outer Ring Road flooding and Hyderabad's 2020 floods followed encroachment of lake beds and their linking channels.
3. **Groundwater depletion**: Concrete stops recharge, so cities that flood in the monsoon run dry in summer, as Bengaluru did in 2024.
4. **Coastal backflow**: Reclaimed mangroves and a narrowed Mithi river worsened Mumbai's July 2005 deluge, when Santacruz recorded 944 mm of rain in a day.

**Ecological and Climatic Implications**

1. **Loss of natural treatment**: The East Kolkata Wetlands, a Ramsar site, treat much of the city's sewage, and reclamation sends waste untreated into rivers.
2. **Biodiversity and heat**: Filling Pallikaranai or Deepor Beel destroys bird and fish habitat, and replacing water with concrete intensifies the urban heat island.
3. **Lost livelihoods**: Fishers and washermen who depended on urban tanks lose their work.

**Conclusion**

Reclamation trades a short-term gain in land for lasting losses in flood safety, water security and ecology. Enforcing the Wetlands Rules 2017 and the Supreme Court's Jagpal Singh (2011) direction to clear encroached ponds, and mapping lake catchments into master plans, would make cities resilient.

What are the environmental implications of the reclamation of water bodies into urban land use ? Explain with examples.

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