Context:

A new study conducted by researchers at IIT-Gandhinagar, published in Nature Hazards (July 13, 2025), provides crucial insights into why flash floods are rising, where they are most likely to occur, and how India can adapt.

Key Findings from the IIT-Gandhinagar Study:

• Flash floods are concentrated in the Himalayan region, the west coast, and central India.
• Only 25% of flash floods are caused by extreme precipitation alone.
• The soil condition before rainfall (especially when already saturated) plays a critical role in triggering flash floods.
• Flash floods occur immediately (within 6 hours) of rainfall in only 23% of cases; more often, they result from multi-day high- and low-intensity rain events.
• Terrain and sub-basin flashiness (how quickly water levels rise) influence the occurrence of flash floods in different regions.

About Flash Floods:

Flash floods are sudden, intense floods occurring within six hours of heavy rainfall. These floods are increasingly becoming one of the most devastating climate-related disasters in India.

Triggered by extreme weather events, these floods result in more than 5,000 deaths annually and cause widespread damage to life, infrastructure, and the environment.

Role of Climate change in the rise in flash flood events

The study highlights a strong correlation between global warming and increased flash flood risk:

• For every 1°C rise in temperature, the atmosphere can hold 7% more moisture, leading to more intense precipitation.
• Between 1981 and 2020:
• Extreme pre-monsoon rainfall events doubled.
• Monsoon-related extremes increased by 56%, post-monsoon by 40%, and winter by 12.5%.
• More than 75% of flash floods occurred during the monsoon season (June–September).
• Since 1995, flash flood events have notably increased, especially in the Brahmaputra, Ganga, and Krishna river basins.

Recommendations for mitigating flash flood risks:

To address the growing threat of flash floods, the researchers recommend region-specific and proactive strategies:

• Tailored early warning systems based on topography, soil saturation, and rainfall patterns — not just precipitation data.
• Identification of new hotspots using updated hydrological data and climate models.
• Construction of climate-resilient infrastructure, especially in vulnerable zones (roads, culverts, embankments).
• Reform in land-use and floodplain planning to prevent encroachment in high-risk areas.
• Community-based disaster preparedness, education, and rapid response systems.

Conclusion:

Flash floods are a stark reminder of the growing climate vulnerability India faces today. As the climate crisis intensifies, there is an urgent need for science-based policymaking, local-level risk assessments, and resilient infrastructure planning. Mitigating flash flood impacts will require multi-sectoral collaboration, informed citizens, and a proactive governance framework.