Enviornment Prelims cum Mains

Assam flood toll mounts to 11, more than 26 lakh hit

In News:

  • Flood and rain-induced landslips have so far claimed 11 lives in Assam.

News Summary

  • Over 26 lakh people in 28 districts of the state have been affected due to floods in Assam.
  • Due to the devastating floods, 70 per cent of the Kaziranga National Park was submerged in water.
    • Note: Kaziranga National Park in Assam is home to the world’s largest population of Indian one-horned rhinoceroses.
  • The Brahmaputra and a number of its tributaries were flowing above danger levels at various places, including Guwahati.
  • The authorities have set up 327 relief camps where more than 16,000 people are taking shelter.
  • Assam has been simultaneously grappling with Acute Encephalitis Syndrome (AES) and Japanese Encephalitis (JE).

 

Flood Control and Disaster Management

  • Around 40 million hectares of land in India is prone to floods as per National Flood Commission report.

Definitions

  • Flood Plain: Periodic floods occur on many rivers, forming a surrounding region known as the flood plain.
  • Flood control refers to all methods used to reduce or prevent the detrimental effects of flood water.

Causes of Floods:

  • Heavy precipitation, severe winds over water, unusual high tides, tsunamis, or failure of dams, levels, retention ponds, or other structures that contained the water.

Rescue & Evacuation

  • Evacuation is a pre-emptive move to protect life and property, where as rescue is a post-disaster phenomenon of helping people to move from areas that have been hit by disaster to a safer place.

 

Flood Management

  • Flood management measures may be broadly categorized as structural measures and administrative/non-structural measures.

Engineering or Structural Measures-These measures bring relief to the flood prone areas by reducing flood flows and thereby the flood levels. The Structural measures include:

  • Embankments/Banks, Flood¬†¬† Walls, Flood Levees: The¬† embankment¬† system¬† in¬† the¬† river¬† restricts the¬† river¬† to¬† its¬† existing¬† course¬† and¬† prevents¬† it from¬†¬† overflowing¬†¬† the¬†¬† In developed areas where adequate space is not available¬† or¬† land¬† is¬† very expensive,¬†¬† concrete or masonry¬† floodwalls are constructed.
  • Dams, Reservoirs¬† and¬† other¬† Water Storages: Lakes, low lying depressions, tanks,¬† dams and reservoirs store significant proportions of flood water and the stored water¬† can be released subsequently when the flood has receded.
  • Channel improvement: Channel improvement aims at increasing the area of flow or the velocit y of flow (or both) to increase its carrying capacity.
  • Desilting/Dredging of Rivers: Selective desilting/dredging at outfalls/confluences or local reaches can be¬† adopted¬† as¬† a¬† measure¬† to¬† tackle¬† the¬† problem locally
  • Anti-erosion works: Bank erosion can be minimised by adopting measures that¬† aim¬† at¬† deflecting¬† the¬† current¬† away from¬† the¬† river¬† bank¬† or¬† which¬† aim¬† at¬† reducing¬† the current¬† along¬† the¬† bank¬† of¬† the¬† river¬† and¬† induce¬† Measures such as permeable¬† spurs,¬† porcupine¬† spurs¬† made¬† of bamboos or of reinforced cement concrete elements reduce the velocit y of flow and thus prevent erosion and induce siltation in the vicinity of the bank.
  • Sea Walls/Coastal Protection Works: Sea walls/coastal protection¬† works¬† in¬† the¬† form¬† of¬† groynes¬† ¬† are constructed¬† to¬† prevent¬† flooding¬† erosion¬† in¬† coastal areas by sea water.

Administrative or Non-structural measures:

These measures focus on mitigation of flood damages by: facilitating timely evacuation of people to safer areas through advance warning of incoming flood; and discouraging creation of valuable assets/settlement in frequent flood prone areas. The measures include:

  • Flood Plain Zoning: Detailed maps of flood prone areas are prepared after a thorough study of flood cycles.
  • Flood forecasting and warning: Flood forecasting enables the people to be forewarned as to when the river is going to use its flood plain, to what ex tent and for how long.

Image result for assam flood

Way ahead

  • Flood management should be seen in the light of environmental degradation, global warming and poor governance at various levels.
  • There is need of a multi-pronged strategy in consonance with the changing rain patterns.
  • Efforts should be taken to check deforestation and organisation of the tree plantation drives at all levels should be intensified.
  • Cleaning of drains and rivulets near the cities to avoid urban flooding.
  • Scientific construction of infrastructures like embankments, flood walls, ring bunds, flood control reservoirs.
  • Checking erosion of land on river banks could help checking the spread of flood.
  • Advance town planning and yearly preparations should be done to mitigate the effects of urban planning.
  • Need of strong centre-states coordination in flood control.

 

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