Flash Floods and Oil Spills | UPSC Mains: Internal Security & Disaster Management PDF Download

In News

Recently, India and Pakistan have been affected due to flash floods .

About

• There have been a series of cloudbursts across the western Himalayan region and they  have wreaked havoc in Himachal Pradesh, the Union territories of Jammu and Kashmir and Ladakh and across the border of Islamabad and Rawalpindi in Pakistan.

About  Flash Floods

• Flash Floods are highly localized events of short duration with a very high peak and usually have less than six hours between the occurrence of the rainfall and peak flood.
• The flood situation worsens in the presence of choked drainage lines or encroachments obstructing the natural flow of water.
• Flash floods have a different character than river floods, notably short time scales and occurring in small spatial scales, which make forecasting of flash floods quite a different challenge than traditional flood forecasting approaches.
• Urban areas are more likely to experience this type of "surface water" flooding because they have a lot of hard surfaces.
  • When rain hits them it can't soak into the ground as it would do in the countryside.

Effects

• It impact the natural environment (including vegetation, agriculture, geomorphology, and pollution) 
• It impacts the human population (entrapments, injuries, fatalities). 

Issues

• Flash floods are among the world’s deadliest natural disasters with more than 5,000 lives lost annually and result in significant social, economic and environmental impacts.
• They also have the highest mortality rate (defined as the number of deaths per several people affected) among different classes of flooding (e.g., riverine, coastal).

Initiatives in this direction

• Flash Flood Guidance Services
  • It is a robust system designed by the India Meteorological Department (IMD) to provide the necessary products in real-time to support the development of warnings for flash floods about 6-12 hours in advance at the watershed level for the flash flood-prone South Asian countries viz. India, Nepal, Bhutan, Bangladesh, and Sri Lanka.

South Asian Flash Flood Guidance System (FFGS)

• The India Meteorological Department (IMD) launched the South Asian FFGS.
• It is aimed at helping disaster management teams.
• Helps governments make timely evacuation plans ahead of the actual event of flooding.

Way Forward 

• There is a need for each member nation to improve their weather observational networks so that more data is available at the time of issuing warnings.
• Soil moisture data is also important and there is a need to augment the existing network.

Flood and its Types 

• It is a temporary inundation of large regions as a result of an increase in reservoir, or of rivers flooding their banks because of heavy rains, high winds, cyclones, storm surge along coast, tsunami, melting snow or dam bursts.
  • Flash Floods : It is defined as floods which occur within six hours of the beginning of heavy rainfall. In case of flash floods, warnings for timely evacuation may not always be possible.
  • River Floods : They are caused by precipitation over large catchment’s areas. These floods normally build up slowly or seasonally and may continue for days or weeks as compared to flash floods.
  • Coastal Floods : They are associated with cyclonic activities like Hurricanes, tropical cyclones etc.
• Catastrophic flooding is often aggravated by wind-induced storm surges along the coast.