Why below average-rains don’t rule out flood threats

Why in the News?

India’s monsoon narrative is undergoing a structural shift: even below-average seasonal rainfall (92% of normal) no longer guarantees safety from floods. The real concern is the sharp rise in short-duration, high-intensity rainfall events, with extreme rainfall incidents increasing to 181 in 2024 (from 160 in 2023). This marks a decisive break from earlier patterns where floods were linked to overall excess rainfall.

Why do below-average monsoons no longer reduce flood risks?

1. Rainfall variability: Seasonal averages conceal intra-seasonal fluctuations, allowing extreme events despite overall deficit rainfall.
2. Short-duration intensity: Rainfall now occurs in short, intense bursts, increasing runoff and flood risk.
3. Historical evidence: Major disasters (e.g., 2015 Chennai floods, 2018 Kerala floods, 2023 Himachal floods) occurred even in relatively normal or deficit rainfall years.

How has the frequency and intensity of extreme rainfall changed over time?

1. Rising frequency: Extreme rainfall events increased from ~89 (2016) to 181 (2024).
2. Threshold revision: IMD reduced extreme rainfall threshold from 244.5 mm to 204.5 mm (2016), reflecting changing climate patterns.
3. Spatial spread: Events are now geographically widespread, affecting both coastal and inland regions.

What explains the increasing unpredictability of rainfall patterns?

1. Climate change impact: Warmer atmosphere holds more moisture, leading to intense precipitation events.
2. Chaotic weather systems: Small initial changes lead to large deviations, limiting forecast accuracy.
3. Forecast limitations: Even with improved models, predicting exact rainfall intensity (250 mm vs 500 mm) remains difficult.

Why are Indian cities increasingly vulnerable to rainfall-induced disasters?

1. Urban flooding: Cities like Delhi, Mumbai, Chennai, Bengaluru face repeated flooding due to poor drainage systems.
2. Unplanned development: Construction on floodplains, wetlands, and water bodies reduces natural absorption capacity.
3. Population density: High-density urban clusters amplify economic and human losses.

What role do past disasters play in understanding current risks?

1. Disaster clustering: India has experienced at least one major rainfall disaster every year since 2013 (e.g., Kedarnath 2013, Uttarakhand 2021, Assam 2022).
2. Record-breaking events:
   1. Jammu & Kashmir (2014): Highest rainfall in 100 years.
   2. Kerala (2018): Worst floods in a century.
3. Trend shift: Disasters are no longer rare but structural features of the monsoon system.

How has the nature of rainfall-related disasters evolved?

1. From scarcity to extremes: Earlier focus on rainfall deficiency has shifted to extreme variability.
2. Urban-centric risks: Flooding increasingly affects urban agglomerations rather than only rural areas.
3. Economic consequences: States spent over 55% of disaster expenditure on floods (2019-2023), indicating high fiscal burden.

Conclusion

India’s monsoon is no longer defined by total rainfall but by distribution, intensity, and timing. The growing disconnect between seasonal averages and disaster outcomes highlights the urgent need for climate-resilient urban planning, improved forecasting systems, and adaptive governance frameworks. The challenge lies not in managing scarcity alone, but in navigating climate-induced volatility.

PYQ Relevance

[UPSC 2020] Account for the huge flooding of million cities in India including the smart ones like Hyderabad and Pune. Suggest lasting remedial measures

Linkage: Increasing extreme rainfall events despite normal/below-normal monsoon directly explain rising urban flooding trends in Indian cities. This PYQ links climatology (monsoon variability) with urban geography issues, making it relevant for both Mains (GS1/GS3) and Prelims (extreme rainfall, IMD classification).