Why floods in Kerala are becoming more severe

Why in the News

Recurrent severe flooding in Kerala is traced to how the land and rivers have been altered, not rainfall alone. The tension is between treating floods as a natural disaster and recognising them as a man made outcome.

What is driving the flood intensity?

1. River siltation: Sediment build up reduces the carrying capacity of rivers.
2. Dam storage loss: The extremely heavy rains have increased the water level in all dams, run by both the state electricity board and the irrigation department. A Comptroller and Auditor General (CAG) audit found major storage loss at reservoirs due to sedimentation, including 47% at Kallarkutty.
3. Wetland shrinkage: Paddy and wetland area fell from 7.93 lakh hectares in 1979 to 1980 to 1.80 lakh in 2023 to 2024.
4. Concretisation: Hard surfaces from urbanisation alter natural drainage. During heavy rains, these impervious surfaces channel stormwater rapidly into nearby rivers and streams, causing water levels to rise within hours.

Why do these factors worsen floods?

1. Reduced buffer: Lost wetlands and paddy no longer absorb excess water. Paddy fields, marshlands and wetlands, are known for absorbing a huge volume of rainfall
2. Faster runoff: Concrete surfaces speed runoff into swollen rivers.
3. Lower channel capacity: Silted rivers overflow at lower volumes.

What is the state’s response?

1. Desilting: The government plans desilting of rivers and reservoirs.
2. Asset register: An asset register will be prepared for rivers, streams and lakes and land auditing is proposed to prevent encroachment of rivers
3. Land use: Restoration of paddy and wetland is under consideration.

Conclusion

Kerala’s floods are the product of altered hydrology as much as heavy rain. The unresolved task is reversing decades of wetland loss and unplanned construction.

Back2Basics

Manufactured sand

Manufactured sand, or M-sand, is an artificial fine aggregate made by crushing hard rocks like granite, basalt, or gneiss into small, sharp grains. It serves as a strong, eco-friendly replacement for natural river sand in modern construction.

How It Is Made

1. Quarrying and Blasting: Hard rock is pulled out from quarries.
2. Primary and Secondary Crushing: Large rocks go through jaw or cone crushers to break down into smaller pieces.
3. Shaping and Sizing: Vertical Shaft Impact (VSI) crushers smash and shape the particles into angular, cubical forms.
4. Screening and Washing: Sieves sort the grain sizes, and water washes away excess rock dust and micro-fines.

Benefits of Manufactured Sand

1. No Impurities: Free of clay, silt, and organic trash found in riverbeds.
2. High Strength: Sharp, angular edges interlock tightly, giving concrete better bonding and compression strength.
3. Eco-Friendly: Stops harmful river dredging that ruins water life and river banks.
4. Consistent Quality: Made in factories with strict size controls instead of relying on nature.

PYQ Relevance

[UPSC 2024] 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.

Linkage: The PYQ examines the causes of urban flooding and India’s policy response to flood disasters. Kerala shows how wetland loss, river siltation, concretisation and altered land use intensify floods despite heavy rainfall, highlighting the need for ecosystem-based flood management.