Repercussions of alternations in the catchment area

Repercussions of alternations in the catchment area

                 

Why is it in the news?

Bellandur , Varthur, Saul Kere and Kaikondrahalli, overflow in these lakes of Bangaluru is a consequence of the loss of interconnectivity of the water bodies, which is a prime reason for the current urban flooding.

When the government took up the work of the removal of suspended slits from the Bellandur and Varthaur lakes in June 2020, that work is yet to be completed.

The main reason for urban floods in Bangalore is the Loss of Interconnectivity between the lakes 

  • The scientist of the Indian Institute of Science (IIS) has confirmed that the Bengaluru lakes are not in a good condition.
  • Bengaluru has lost 45 to 50% of interconnectivity between the lakes, due to unplanned urban development and encroachment.
  • which is the prime reason for the decaying of the lake due to sewage inflow and also led to frequent flooding in the areas closer to it.
  • In the 19th century, Bangalore had a 740 sq km region and 1452 water bodies with a capacity of water storage of 35 TMC (thousand million cubic feet), which helps in both harvesting rainwater and also to mitigate floods.
  • But at present, Banlaguru has left with only 193 lakes and most of them lost connectivity due to the blocking of the stormwater drains (rajakulaves) because of encroachment or solid wastes.
  • The clag deposition in the lakes decreased the water holding capacity of the lakes.
  •  The number of wetlands in Bangalore also reduced from 285 to 194.

 

Repercussions of Alteration of Catchment areas  

  • Bangaluru has a significant interconnected lake system.
  • To secure the continuation of the Hydrological functions of the drains and flood plains, the valleys zones connecting the lakes must be protected.
  • But, the habitants of these valley zones of the cities continuously abuse the delicate ecosystem despite norms to protect them.
  • Due to large-scale catchment alteration with changes in land use and land cover, the Bellandur-Varthur wetland ecosystem in Bangalore, experiencing the threat.
  • In 2004  the wetland was started to convert into mixed land, to be used to build both residential and office complexes.
  •  
  • The upstream lakes to Bellandur and Varthur, which include Kaikondrahalli and Saul Kere, are also overflowing due to the rampant encroachments of stormwater drains.
  • Because of rampant encroachment of stormwater drains, there is an overflow in the upstream lakes to Belladur and Vathur , including the kaikondrahalli and Saul Kere.
  • A study by scientists stated that the stormwater drain connecting Bellandur lake from the city market side was narrowed to 28.5 m against the original width of 60 m.
  • The groundwater restoration structure was not taken up due to the flow of sewage in SWDs.
  • Drains and water bodies are not interconnected  and linkage linkage between drains was absent
  • This affected the free flow of stormwater leading to frequent flooding in many parts of the city.

Failure of removal of clag

  •  In 2020 June, Bangalore Development Authority commenced the removal of clag from the Balladur and Vathur Lakes. But due to the pandemic, the work is yet to be completed.
  • Most of these lakes and drains in this series are either encroached or not the removal of clag leading to flooding.

What we can conclude 

 

  • Hence, there is a very urgent need to include public open spaces within the urban fabric in the form of storm management infrastructure, which could help our cities transform into water-sensitive cities.
  •  And the development in urban areas must be done under some environment-friendly planning program 

Sources 

 

bit.ly/bangaloreflood_22

https://bit.ly/T_I_E-bangaloreflood22

https://bit.ly/waterlogging

Plutus IAS Daily Current Affairs Eng Med 22 Sep 2022

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