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Importance of Bellandur Lake in the ecosystem of Bangalore

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Bellandur Lake is the biggest water body in Bangalore. In our metro we are depending heavily water bodies as wet lands in Nitrogen cycling. Bellandur Lake thus plays an important role in this cycle as a natural wetland. The three main streams of sewage are

  1. Koramangala Chellaghatta valley through Bellandur Lake (384-500MLD)
  2. Hebbal Nagavara (180MLD)
  3. Vrishavabhati Valley (500MLD)

Indian Institute of Science, Bangalore has a strong group working on Carbon and nitrogen Cycle relevant to the city of Bangalore. It is now becoming important as per them, to examine how efficiently we are managing our C and N budgets in urban and peri-urban areas. Are these methods sustainable? These issues are dealt at the Indian Institute of Science Bangalore by carrying out pioneering research on the subject.

“   1. If we consider the area of Bangalore as 250sq km (the densely populated area) we get a deposition of 1500 kg N /ha/yr. This is very high deposition rate and will lead to N contamination because the deposition rate outstrips the natural processes for N cycling    

    2. Urban -bore well(water source) and soak-pit /sewage proximity–1-9m apart ≥10yr exposure to 103higher bacterial load/pathogen risk -higher coliformdiarrhoeaand new pathogenic species, 15-20m travel though soil inadequate for safety –60-200 mg/L NO3 groundwater–Smaller molecules (Pharmaco-biotics) →→→NEW Research  

Water composition of Bellandur Lake Water as reported in the IISc report (18 Nov 2006) shows that there are places where NO3 of ground water is above permissible limits and even greater than 150mg/L, in some places.

See the attached  IISc report. There are three major inlets to the Lake viz Indiranagar, Airport and Agara sides. The pictures of these inlets are good. Have a look.

Chanakya_SessionIII_28dec02006.pdf569.48 KB


sanjayv's picture

why is sewage going into a lake?

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Something I do not understand at all - why is sewage being pumped into a lake and then treated?  The valleys are designed for rainwater to flow and here you have sewage added into the mix.  Now we have all these residential properties all around the lake - what water do their borewells pull out.  How about the coconut plantations around? I will not have the guts to drink any water from a tender coconut dropped from a tree there.


psaram42's picture

The Bellandur Problem

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Dear Sanjay V,

As an engineer like you, I would also feel the same apprehensions one gets with the realization of some hard facts of life. Is the Bellandur lake water being polluted unnecessarily? How do the nearby properties manage to get drinking water?

Let me explain with my limited knowledge:- If you read the attached research paper of IISc you have this slide:-

  1. Nitrogen and Carbon Flows through Bellandur Lake
  2. Bellandur Lake as a natural wetland
  3. treating wastewater
  4. ChanakyaHN

I want to impress upon you the second point viz Bellandur Lake as a natural wetland. Natural Wet Land is a land with water which plays an important role in carbon/Nitrogen cycle in natural purification of human solid waste in the sewage water. Another application is gober gas plant which we are more comfortable with. Gober gas plant is better application where we use even the gases generated as fuel. Pardon me if I am bit wrong in details. Please read the Chankya Document fully to get more details of what are the Lacunas in Bellandur Tank in treatment of sewage water.

Please notice in the report that there is a minimum distance specified for digging bore wells to avoid any health hazards.


sanjayv's picture

IISc report

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I downloaded the IISc report PSA sir, but would need to find some time to go through it.  Thanks for locating this. comment guidelines

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