Enviornment Prelims 2021 Prelims cum Mains

IMD launches guidance system for South Asia to tackle flash floods

In News:

  • The India Meteorological Department (IMD) has launched the South Asian Flash Flood Guidance System (FFGS).

About: Flash Floods

  • Flooding is an overflowing of water onto land that is normally dry.
  • Flash floods are sudden surges in water levels during or following an intense spell of rain, occuring in a short time duration over a localised area.
  • They are the most dangerous kind of floods, because they combine the destructive power of a flood with incredible speed.
  • They can happen anywhere, within minutes, limiting the time available to warn and protect the public.
  • Flash floods are among the world’s deadliest natural disasters, and result in significant social, economic and environmental impacts along with loss of lives.

Causes:

  • Flash floods most often due to extremely heavy rainfall from thunderstorms, with the magnitude so heavy it easily exceeds the ability of the ground to absorb it.
  • Other causes of flash include tropical storms, cyclones, failure of dams, levees etc.

Rainfall and Type of Soil as main factors:

  • In general,  rainfall and type of soil are the major factors that determine the probability of flash floods.
  • Usually, some moisture is retained by the soil when it rains, and once the soil gets saturated, the runoff from the soil starts.
  • Thus, the soil’s ability to absorb rainwater influences the probability of flash floods.
  • The intensity of rainfall, or the run-off of water from dam breaks etc, will determine whether a flashflood will occur.
  • For instance in states like Rajasthan and Madhya Pradesh, where the soil is more absorbent, even 100 to 200 millimeters (4 to 8 inches) of rainfall may not cause floods.
  • However in regions like Ladakh, where the terrain consists mostly of loose soil, flash floods can occur with less rainfall.

Background:

  • The World Meteorological Organization (WMO) recognized that flash floods have a particularly disastrous impact on lives and properties of the affected populations. Despite high mortality, there was no robust forecasting or warning system for flash floods.
  • In this regard, the 15th WMO Congress approved the implementation of a Flash Flood Guidance System (FFGS) project with global coverage.
  • It was then developed by the WMO Commission for Hydrology (CHy) jointly with the WMO Commission for Basic Systems (CBS) and in collaboration with the US National Weather Service, the US Hydrologic Research Center (HRC) and USAID/OFDA.
  • South Asia FFGS:
    • Initially, South Asia FFGS developed by the Hydrologic Research Center (HRC) was run for about 1.5 years from its centre in USA.
    • However, it was shutdown because of lack of regional collaboration and cooperation to make progress in the regional implementation of the system.
    • Later, regional South Asian countries expressed the importance of the project and wished to move forward for the regional implementation.
    • India was designated as a nodal centre by WMO for preparing flash-flood forecasts in south-east asian countries.
    • The India Meteorological Department (IMD) has been working on a Flash Flood Guidance System (FFGS) that will predict the possibility of flash floods up to six hours in advance and alert disaster relief forces as well as residents.

Recent flash flood in Hyderabad:

  • Flash flood situation worsens in heavily populated urban areas, with the presence of choked drainage lines or encroachments obstructing the natural flow of water.
  • In the latest incident involving flash floods in October 2020, Hyderabad city was battered by heavy rain, resulting in massive flooding which inundated roads.
  • The city recorded 191 mm of rain within the span of a few hours, the heaviest in 97 years recorded in October.
  • Several water bodies in the city breached danger levels, worsening the overall flood situation.
  • Nearly 70 people lost their lives and many hundreds were displaced from their homes.

News Summary:

  • The India Meteorological Department (IMD) has launched the South Asian Flash Flood Guidance System (FFGS).
  • The system will use satellite images and on-ground equipment to track real-time rainfall in any part of the country. The dedicated FFGS centre will be established in New Delhi.
  • It is is aimed at helping disaster management teams and governments make timely evacuation plans ahead of the actual event of flooding.
  • India is leading a delegation of nations, including Bhutan, Sri Lanka, Bangladesh and Nepal, in sharing hydrological and meteorological data towards preparing flash flood forecasts.

Significance:

  • Flash floods can inundate vast areas within a few hours as compared to general floods that take days or even weeks to develop.
  • Therefore FFGS could be a significant tool in disaster risk reduction by providing early warning.
  • Based on the rainfall and potential flooding scenario, flash flood warnings will be issued to respective nations.
  • Flash flood threat warning will be issued six hours in advance, whereas flood risk warning will be issued 24 hours in advance.
  • Warnings about watershed level will be issued 12 hours in advance.

Way ahead:

  • India stressed on the need for each member-nation to improve their weather observational networks so that more data is available at the time of issuing warnings.
  • Apart from rainfall data, soil moisture data is also important and there is a need to augment the existing network in all the regional South Asian countries.
  • There is also a need to disseminate warnings to the last-mile beneficiary using appropriate media.

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