Flash floods in Kerala: A junked breakwater plan may have been Achilles’ heel

Subject: Geography

Section: Physical geography

Context:

Flash floods drenched Kerala’s capital, Thiruvananthapuram. Most low-lying areas of the city are still under water. Significant rains were recorded in the districts of Ernakulam, Kollam and Alappuzha, creating waterlogging and stagnation in several regions.

Why the flooding occurred:

These torrential rains in Kerala were caused by cyclonic circulations over the Arabian Sea and Lakshadweep.
TheAmayizhanchan Canal near Kannamoola connects to Akkulam Lake and drains rainwater into the Arabian Sea via Veli Pozhi, an estuary.
But the final component of the project titled Operation Anantha is missing — which may have led to flooding in the city.
The flood mitigation project included a breakwater at Veli so that excess water from Akkulam lake would drain out to the sea through the year. But, its construction was halted following opposition from the Veli locals due to concerns including:
- Chemical effluents and plastic waste will be drained into the marine ecosystem
- Coastal erosion
Solution lies in:
- Digital mapping of land-use changes in urban landscapes.
- Building early warning systems,
- Infrastructure that can withstand water overflow and
- Suitable land-use planning
- Check dams have been suggested to prioritize watershed-based management, afforestation and soil conservation.
- Water-efficient farming practices, Use of drought-resistant crops and implementation of micro-irrigation.

Flash flood:

A flood caused by heavy or excessive rainfall in a short period of time, generally less than 6 hours.
Flash floods are usually characterized by raging torrents after heavy rains that rip through river beds, urban streets, or mountain canyons sweeping everything before them.
They can occur within minutes or a few hours of excessive rainfall. They can also occur even if no rain has fallen, for instance after a levee or dam has failed, or after a sudden release of water by a debris or ice jam.

Source: DownToEarth