Why low-intensity Cyclone Fengal caused large-scale destruction

Sub : Geo

Sec : Climatology

Context:

Cyclone Fengal caused widespread destruction despite being a low-intensity storm.

Comparison with Past Cyclones:

Fengal was categorised as a cyclonic storm with wind speeds of 75-95 kmph.
Odisha Super Cyclone (1999): 260 kmph
Cyclone Phailin (2013): 215 kmph
Cyclone Amphan (2020): 185 kmph
While these storms caused extensive damage due to their high wind speeds, Cyclone Fengal caused significant destruction despite being relatively weaker.

Impact of Cyclone Fengal:

Casualties: 12 deaths (mostly in Tamil Nadu).
Rainfall Records:
- Mailam village (Villupuram): 510 mm in 24 hours.
- Puducherry: 490 mm in one day, surpassing the 2004 record of 211 mm.
Flooding and Inundation:
- Highways submerged, disrupting air, rail, and road transport.
- Overflowing rivers and lakes caused widespread damage to property and crops.

Reasons for High Destruction:

Slow Movement of Fengal:
- Cyclone Fengal moved at speeds as low as 6 kmph and became stationary for 12 hours after landfall.
- This prolonged its impact over affected regions, leading to excessive rainfall and flooding.
Prolonged Rainfall:
- Continuous heavy rains overwhelmed drainage systems and caused waterlogging in urban and rural areas.
Persistence After Landfall:
- Unlike typical cyclones that weaken after hitting land, Fengal retained its strength, amplifying the damage.
Precedents in Recent Cyclones:
- In comparison, more intense cyclones (e.g., Cyclone Dana in October 2023) resulted in minimal casualties due to faster movement and better preparedness.

Key Takeaways:

Cyclone intensity is not the sole determinant of its destructive potential; movement, duration, and rainfall also play crucial roles.
Slow-moving cyclones, like Fengal, pose unique challenges by causing prolonged impact, particularly through flooding and infrastructure damage.
Enhanced planning for slow-moving storms, including improved drainage systems and evacuation strategies, is essential to mitigate future risks.

Cyclone Categories by IMD:

The India Meteorological Department (IMD) classifies cyclones based on wind speed:
Low pressure: < 31 kmph
Depression: 31-49 kmph
Deep depression: 50-61 kmph
Cyclonic storm: 62-88 kmph
Severe cyclonic storm: 89-117 kmph
Very severe cyclonic storm: 118-221 kmph
Super cyclone: > 222 kmph

Source: IE