Flash Flood Guidance Services

#GS1 #Geography 

Ministry of Earth Sciences has dedicated Flash Flood Guidance services, first of its kind for South Asian countries namely India, Bangladesh, Bhutan, Nepal and Sri Lanka.


What are ‘flash floods’?

  • Flash floods are characterised by very fast rise and recession of flow of small volume and high discharge, which causes high damages because of suddenness. This occurs in hilly and not too hilly regions and sloping lands where heavy rainfall and thunderstorms or cloudbursts are common.
  • A flood caused by heavy or excessive rainfall in a short period of time, generally less than 6 hours. Flash floods are usually characterised by raging torrents after heavy rains that rip through river beds, urban streets, or mountain canyons sweeping everything before them. They can occur within minutes or a few hours of excessive rainfall.
  • It may be caused by heavy rain associated with a severe thunderstorm, hurricane, tropical storm, or meltwater from ice or snow flowing over ice sheets or snowfields.
  • Flash Floods can also occur due to Dam or Levee Breaks, and/or Mudslides (Debris Flow).
  • In areas on or near volcanoes, flash floods have also occurred after eruptions, when glaciers have been melted by the intense heat.
  • The intensity of the rainfall, the location and distribution of the rainfall, the land use and topography, vegetation types and growth/density, soil type, and soil water-content all determine just how quickly the Flash Flooding may occur, and influence where it may occur.


Details about the ‘Flash Flood Guidance System’ 

  • The Flash Flood Guidance is a robust system designed to provide the necessary information in real-time to support the development of warnings for flash floods about 6- 12 hours in advance at the watershed level with resolution of 4km x 4km for the Flash Flood prone South Asian countries viz. India, Nepal, Bhutan, Bangladesh and Sri Lanka.
  • The system has in-depth science, dynamics and diagnostics to provide guidance for the possible occurrences of flash floods at local level.
  • The model will provide forecasts by computing likelihood of rainfall and soil moisture levels to warn of possible floods. It will carry out forecasts by using combination of satellite mapping and ground-based observation.
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