Thursday, May 3, 2018

Wetland Maintenance - Jakkur Lake

Summary
Jakkur Lake is on approximately 160 acres and is located in the Northern part of Bangalore to the right of NH44 near Yelahanka. The lake falls within Hebbal Valley as part of the Yellamallappa Chetty lake series in northern Bangalore. There are two entrances to the lake. One from the South and the other from the East.
To the northwest of the lake, there is a BWSSB-operated 10 MLD STP which discharges an average of 7-8.5 ML into the lake each day. BWSSB checks the water quality before it is let into the wetland.
In 2008 BDA/BBMP constructed a wetland and rejuvenated Jakkur Lake.  Since then the lake has seen lots of changes - a walking path, Community Centre, Security building, Fishermans hut, Toilets to name a few.

A constructed wetland covers approximately 7 acres in the northern part of the lake. There are various species of aquatic plants in the wetland. Typha is planted at the inlet and on the edge of the wetland, followed by an algal pond. Fishermen at the lake maintain the wetland and the lake by trimming/harvesting the plants as required. Women from a self help group cut the grass around the wetland. Grass cutters also cut grass and harvest alligator weed for fodder.  Grass cutters sometimes cut Typha too.


Inlets

There are four primary inlets: 
  • STP treated water  enters from the north into the wetland.
  • Naala 1 -  Mix of storm and sewage flowing from Agrahara lake outlet enters from the east of the lake and is let into the lake directly.
  • Naala 2 - Mix of storm water  and sewage water enters from the north of the lake into the wetland.
  • Naala 3 - Presently, there is no inflow of wastewater from this inlet as that part of the drain opening into the lake was reportedly blocked by some chemical industry. We were also told that, prior to closing the drain, the overflow from Shivanahalli lake used to enter Jakkur Lake through this inlet

Outlets

There are two outlets in the southern side of the lake. Both of the lake outlets are overflow structures in the south of the lake. The two outlet naalas converge downstream and flow to Rachenahalli Lake.


Maintenance of Wetland 

     

 A 7-acre constructed wetland in the north of the lake has mostly been left to grow naturally. This wetland accounts for approximately 4.4% of the total lake area. There is a bund created with an outlet into the lake. There are species of plants in the wetland such as Typha, Alligator weed, Water Hyacinth.
  

   
Alligator Weed                                                           Duck Weed

                                
Water Hyacinth                                                          Typha

Harvesting and cutting of Hyacinth and Typha

  • With untreated sewage water entering, there is growth of Hyacinth in the wetland and lake.  It is observed that the growth of Hyacinth increases when the inflow of sewage water increases. It is also observed that the plant species thrive during monsoon season.
  • Hyacinth is harvested to control their growth. They are usually left to complete their life cycle and removed when dry.  
  • Typha is also seen in plenty around the wetland. Dry Typha is cut by the women and the grass cutters.

Water Quality

  • Water quality data of the STP treated water which is let into the wetland is maintained by BWSSB.
  • KSPCB collects water from 5 different locations and does the analysis periodically.
  • Atree research paper:  http://www.ias.ac.in/article/fulltext/reso/022/03/0279-0290  
  • Dr TV Ramachandra’s  research paper: http://wgbis.ces.iisc.ernet.in/biodiversity/pubs/ETR/ETR76/sec6.html
  • Dr. Chanakya’s(IISc) students check for microbial and algae growth.  They are studying water quality for  microbial content.



Maintenance of lake and surrounding area
  • Jala Poshan, a not-for-profit organization officially took over the lake in 2014. It has played an important role in rejuvenating the lake by organizing resources such as labour and finances and driving the work at Jakkur Lake by coordinating between various organizations and monitoring the progress of the work. They have recently started  experimenting with floating wetlands in the lake.
  • Installed leaf composters, Vermicompost pits, Composting sheds and hedges
  • Created Butterfly garden and planted trees. There are over 5000 trees around the lake.
  • In addition to Jala Poshan volunteers, there are 3 groups involved in maintenance of the Lake. 
    • Women from self help group 
    • Fishermen
    • Grass Cutters

Women from self help group
  • 160 acre lake with 5 km perimeter requires lots of maintenance. Jala Poshan has appointed 6 women from the self help group to clean the land area around the lake. They deweed, cut grass and prune the trees which are then composted. Male labourers are hired temporarily whenever required.
  • Leaf composters are placed around the lake. Cow dung slurry is used to accelerate the composting process.  Twigs are composted in pits. 
  • There are Vermicompost pits, 

Grass Cutters


  • Are from nearby villages who cut grass in the lake; Grass Cutters harvest Alligator weed from the shoreline  which is used as fodder for their livestock
  • They visit the lake everyday and have free access to the lake.  
  • Being native to the area they are sensitive to the environment and do not destroy it.  
  • They cut grass/weed in a manner where it shoots again and take only those species of plants/grass which is useful to the livestock.
  • They are not paid by Jala Poshan but are able to take the grass for free for their own purposes

Fishermen
  
Pic by Dr. Annapurna
  • Spend their time fishing and keeping the main water body clean. 
  • Keep the lake clean from garbage(paper/plastic).
  • Harvest hyacinth and other weed which may then be used for compost. 
  • Maintain a narrow line of hyacinth along the shoreline and also at the inlets and outlets at all times.
  • Fisheries department is notified if there are issues with water quality. The department suggests solutions to the fishermen who are then responsible for carrying out those tasks. It is in their interest to ensure the lake is healthy as it will allow for a better fish population. 
  • When Jala Poshan brings an expert to the lake, fishermen are always present in order to understand and make the required changes. 


Safety Measures
All the workers have access to a shed that holds protective gear such as gloves, shoes, and life jackets. In many cases, the workers prefer to go without as they believe the gear hinders their ability to work. However, Jala Poshan requires them to wear shoes when working in areas with tall grasses which may be home to snakes. 


Funds
The maintenance of the lake costs between 1.5-2 lakh INR per month. While the BBMP does not allow official income-generating activities at the lake, it allows Jala Poshan to hold fundraising events that help offset the costs of maintenance and improvements. In addition, this work is funded through Jala Poshan by their donors and any dedicated BBMP funds. 


Challenges
Funding
  • Maintenance of Wetland has been a challenge as it is growing naturally since it was constructed in 2008. Jalaposhan is waiting for funding from BBMP to rejuvenate the wetland. 

STP downtime
  • It has been observed that sometimes the aerator of the STP stops. The reason for this and the quality of water entering the wetland is not known.

Sewage 
  • Sewage enters directly into the lake through some inlets. Plan is to raise the height of the inlet by one brick to increase the retention time of the water. Water Hyacinth growing at the inlet will help in purifying the water to some extent before it enters the lake.

Chemicals in SWD
  • Some textile industries (side stream of the lake) use dyes, and waste water from these industries was being let into the storm water drain without treating.
  • Fisherman and Jala Poshan members look out for the turbidity and frothing of the water which enters from the storm water drains. If the turbidity increases they get the water analysed. Frothing in the water is an indication of effluents/chemicals in it. This is then traced back to the industries.

Disconnected SWD
  • A SWD has been disconnected as part of the drain is blocked by some chemical industries. There is no water entering the lake from this inlet. Jala Poshan members plan to define the SWD and rejuvenate the 3 SWD at the lake by approaching the SWD department of BBMP to get the work done.
  • Also, one of the outlets is closed due to a railway line.

Future plans
  • Jala Poshan members are thinking of recreating/rejuvenating the wetland and provide easy access to different parts of the wetland by means of vertical and horizontal partitions. 
  • Increasing the bund height by 1 to 2 feet will help in maintenance and retention of water for longer period in the wetland before getting into the lake.
  • Have a wetland maintenance plan which would allow the grasscutters, fishermen, and other stakeholders to agree upon and work under the same guidelines with regards to the harvesting of various plant species. 
  • Engage with experts Dr. TV Ramachandra, Mr.Yellappa Reddy, Atree, Mr. Vishwanath and others to scientifically come up with a plan for maintenance of the wetland.

Contact Info

References






3 comments:

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Unknown said...

Very nice report. Thank you...

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