The Study has found that flash floods are mainly centred in the Himalayas, the west coast, and Central India: Key Findings:

• Extremely flash flood-prone sub-basins are located in the Brahmaputra, Narmada, Tapi, Mahanadi, Brahmani, and West Coast River basins.
• High flash flood susceptibility is also observed in parts of the Godavari, Ganga, Mahi, and Indus River basins.

What are Flash Floods?

• Definition: A flash flood is a flood of short duration with a relatively high peak discharge in which the time interval between the observable causative event and the flood is less than four to six hours (WMO, 2006).
• Flash Floods and India:
  • Between 2020-2022, the number of flash flood events increased from 132 to 184 (Jal Shakti Ministry).
  • Every year, more than 5,000 people die due to Flash Floods

Key Drivers of Flash Floods

• 25% Flash floods occur typically within six hours of heavy rainfall often triggered by cloudbursts. E.g., Himalayan regions.
• Steep Topography and Narrow River Channels in Mountainous Regions: Facilitating rapid water accumulation and downstream surge.
• Saturated Soil (due to concrete, roads): Water fails to percolate and results in sudden surface runoff.
• Sudden release of dams, embankments, or check dams due to pressure buildup from upstream rainwater.