Sankey Lake: waiting for an Immediate Sensible Action

T.V. Ramachandra*    Asulabha .K S  Sincy .V. Vinay .S Sudarshan p. Bhat Bharath H. Aithal
Energy & Wetlands Research Group, Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012
*Corresponding author: cestvr@ces.iisc.ernet.in, energy@ces.iisc.ernet.in
Ecological Impact Assessment of the Proposed Building Activities (Report prepared in 2004)

T. V Ramachandra

Ahalya N

Harish Bhat

Sudhira H. S

Karthick B.

T. V Jagadeeshan

Lakes/Tanks are important components of the ecosystem with various beneficial functions. The various functions of lakes and wetlands include sustaining life processes, water storage for domestic, agricultural and industrial usage, protection from storms and floods, recharge of ground water, water purification, erosion control and stabilization of local climate. Thus they help to maintain the ecological balance of the region. Lakes/Tanks in Bangalore occupy about 4.8% of the city’s geographical area (640 sq.km), which covers both urban and rural areas. All the lakes/tanks in Bangalore are man-made, which were built to serve the needs of irrigated agriculture and drinking water. One such tank/lake is Sankey, which is situated in the western part of the city between Malleswaram and Sadashivnagar. Col. Sankey built the tank/lake during 1882 to meet the drinking water demand of the nearby areas.  The tank covers an area of 12.8 hectares and its catchment area is approximately 343 hectares (Figure 1 and 2).  A public recreation park and corporation swimming pool is present at the southern part and a nursery at the northern side of the tank. The northern side has a good vegetation cover, which is one of the reasons for attracting large population of migratory birds to this wetland (Refer Annexure for Checklist of birds and plants).


 
Figure 1: Satellite imagery of Sankey tank and its catchment area (The marked area shows the proposed activities).


Figure 2: Water spread area of Sankey tank.

Proposed activities on the tank/lake bed: Construction of high-rise buildings in the immediate vicinity of the lake is being proposed. The construction activities would prove detrimental to the hydrological (water quality, amount of water flowing into the lake, quality of groundwater, etc) and ecological (planktons, birds, fish, etc) aspects of the Sankey tank. The impacts of the proposed construction activities are:

Impacts of proposed activities

  1. The construction activities would lead to alteration in the hydrologic regime, which would lead to decreased water yield.
  2. The construction activities would result in cutting of trees, which would increase soil erosion. This in turn will increase the inflow of silt into the lake.
  3. The inflow of silt will lead to sedimentation in the lake, ultimately decreasing the water storage capacity of the lake.
  4. Sankey tank is rich in floral and faunal resources (Refer Annexure). The developmental activity will affect the faunal and floral composition of this wetland. The avifauna (birds) would be severely affected due to the construction of high rise buildings on the lake bed.
  5. The proposed construction would increase the water demand and the demand for water would lead to high ground water tapping (would also reduce surface water in the lake).
  6. Further investigations on the carrying capacities are needed especially for lakebed as the it is not conducive for the construction of high-rise buildings due to the underlying geology, topography and ecology.
  7. The natural connectivity between lakes would be affected by the anthropogenic activities (subsurface, etc.) leading to a loss of interconnectivity (for example: drain from Rajajinagar connecting Sankey was encroached (by high raise building)  leading to frequent flooding and water stagnation in the region, affecting the property and people’s livelihood).

Reduced water yield in the catchment as well as enhanced sediment yield (along with pollutants) would lead to reduced ecological functions of the lake. This would eventually leads to the disappearance of the lake. Thus to protect and conserve the lake, we need watershed-based approach for the sustainable management of the biotic and abiotic components of the ecosystem. Soil and water conservation is a very important aspect of watershed management. This would ensure in maintaining the hydrological balance in the ecosystem. The watershed - based management would ensure a vegetation cover, which will arrest the soil erosion. This will in turn enhance the water-holding capacity of the lake and ascertain the conservation of the biodiversity of the lake, namely its flora and fauna.

In the interest of the society and future generation, onus is on the proponent of these construction activities to hand over this land (acquired clandestinely) to the government of Karnataka to develop as children’s park. This would also help in showcasing the commitment of citizens of Bangalore (in this case – proponent of massive construction activities in the lake bed)  towards maintaining inter and intra generation equity.

Annexure:

Birds Sighted in and around Sankey Tank on 20th August 2004 during 10 - 12:30 PM.

  1. House Crow
  2. Jungle Crow
  3. Common Myna
  4. Small Green Barbet
  5. Blue Rock Pigeon
  6. Rose Ringed Parakeet
  7. Pied Wagtail
  8. Little Cormorant
  9. Koel
  10. Pariah Kite

Bird Checklist in Sankey catchment (R. J  Ranjit Daniel, 1992)

  1. Large Grey Babbler
  2. White Headed Babbler
  3. Crimson Breasted Barbet
  4. Small Green Barbet
  5. Blue-tailed Bee-eater
  6. Small Green Bee-eater
  7. Bluechat
  8. Bluethroat
  9. Red Vented Bulbul
  10. Red Whiskered Bulbul
  11. White Browed Bulbul
  12. Pied Bushchat
  13. Bushlark
  14. Crested Honey Buzzard
  15. Longlegged Buzzard
  16. Goldfronted Chloropsis
  17. Coot
  18. Little Cormorant
  19. Greater Coucal
  20. House Crow
  21. Jungle Crow
  22. Common Hawk-Cuckoo
  23. Indian Cuckoo
  24. Pied Crested Cuckoo
  25. Plaintive Cuckoo
  26. Blackheaded Cuckoo-Shrike
  27. Large Cuckoo-Shrike
  28. Black Drongo
  29. Grey Drongo
  30. Haircrested Drongo
  31. Whitebellied Drongo
  32. Little Brown Dove
  33. Red Turtle Dove
  34. Rufous Turtle Dove
  35. Spotted Dove
  36. Booted Eagle
  37. Crested Hawk-Eagle
  38. Short-toed Eagle
  39. Tawny Eagle
  40. White-eyed Buzzard Eagle
  41. Cattle Egret
  42. Little Egret
  43. Smaller Egret
  44. Shaheen Falcon
  45. Ashycrowned Finch-Lark
  46. Tickell’s Flower Pecker
  47. Blacknaped Blue Flycatcher
  48. Brown Flycatcher
  49. Paradise Flycatcher
  50. Redbreasted Flycatcher
  51. Tickell’s Blue Flycatcher
  52. Verditer Flycatcher
  53. Pale Harrier
  54. Asiatic Sparrow Hawk
  55. Grey Heron
  56. Night Heron
  57. Pond Heron
  58. Hoopoe
  59. Common Iora
  60. Kestrel
  61. Blackcapped Kingfisher
  62. Pied Kingfisher
  63. Small Blue Kingfisher
  64. Whitebreasted Kingfisher
  65. Blackwinged Kite
  66. Brahminy Kite
  67. Indian Kite
  68. Indian Koel
  69. Redwattled Lapwing
  70. Yellowwattled Lapwing
  71. Collared Sand Martin
  72. Dusky Crag Martin
  73. Redheaded Merlin
  74. Small Minivet
  75. Blackheaded Munia
  76. Red Munia
  77. Spotted Munia
  78. Whitebacked Munia
  79. Whitethroated Munia
  80. Blackheaded Myna
  81. Greyheaded Myna
  82. Indian Myna
  83. Jungle Myna
  84. Little Nightjar
  85. Golden Oriole
  86. Barn Owl
  87. Collared Scops Owl
  88. Mottled Wood Owl
  89. Spotted Owlet
  90. Blossomheaded Parakeet
  91. Roseringed Parakeet
  92. Grey Partridge
  93. Rosy Pastor
  94. Grey Pelican
  95. Blue Rock Pigeon
  96. Indian Tree Pipit
  97. Paddyfield Pipit
  98. Indian Pitta
  99. Yellowlegged Button Quail
  100. Black Redstart
  101. Indian Roller
  102. Indian Robin
  103. Magpie Robin
  104. Common Sandpiper
  105. Green Sandpiper
  106. Shikra
  107. Baybacked Shrike
  108. Brown Shrike
  109. Small Skylark
  110. Common Snipe
  111. Painted Snipe
  112. House Sparrow
  113. Blackwinged Stilt
  114. Painted Stork
  115. Maroonbreasted Sunbird
  116. Purple Sunbird
  117. Purple Rumped Sunbird
  118. Common Swallow
  119. Redrumped Swallow
  120. Wiretailed Swallow
  121. Alpine Swift
  122. House Swift
  123. Tailor Bird
  124. Lesser Whistling Teal
  125. Blue Headed Rock Thrush
  126. Whitethroated Ground Thrush
  127. Grey Tit
  128. Tree Pie
  129. Whitebacked Vulture
  130. White Scavenger Vulture
  131. Grey Wagtail
  132. Large Pied Wagtail
  133. White Wagtail
  134. Yellow Wagtail
  135. Ashy Wren Warbler
  136. Blyth’s Reed Warbler
  137. Greenish Leaf Warbler
  138. Large Crowned Leaf Warbler
  139. Orphean Warbler
  140. Plain Wren Warbler
  141. Streaked Fantail Warbler
  142. Tickell’s Leaf Warbler
  143. Whitebreasted Waterhen
  144. Common Weaverbird
  145. White-eye
  146. Lesser Whitethroat
  147. Woodcock
  148. Indian Woodshrike

Plant species: (As seen from top of the adjacent building – Aranya Bhavan: Bird eye view)

  1. Caryota urens
  2. Ficus religiosa
  3. Artocarpus heterophyllus
  4. Santalum album
  5. Brousonetia papyrifera
  6. Pongamia glabra
  7. Grewelia robusta
  8. Spathodea campanulata
  9. Causuarina equisetifolia
  10. Cassia spectabilis
  11. Eucalyptus sp.
  12. Ricinus comunis
  13. Polyathea longifolia
  14. Mangifera indica
  15. Peltophorum pterocarpum

Reference:

Ramachandra T.V., Kiran, R., Ahalya N, 2002, Status, Conservation and Management of Wetlands, Allied Publishers Pvt Ltd, Bangalore.

Ranjit Daniels, R. J., 1992. Of Feathers and Colours: Birds of Urban South India. Indian Institute of Science, Bangalore, India.

Lakshman Rau, 1986, Report of the Expert Committee for Preservation, Restoration or otherwise of the existing tanks in Bangalore Meteropoliton Area.

Water percolation in this region happens due to green cover. But, removal of green cover with large scale buildings and paved surfaces, would reduce and affect the hydrologic regime of the lake. Lake is being used by all sections of the society – recreation (children and elders), education (science experiment), livelihood (fishing, etc.),  etc. Need to protect the lake to maintain inter and intrageneration equity - 'hold the natural and cultural environment of the Earth in common both with other members of the present generation and with other generations, past, present and future' (Weiss, 1990). It means that we inherit the Earth from previous generations and have an obligation to pass it on in reasonable condition to future generations.

Weiss, Edith Brown 1990, 'In fairness to future generations', Environment, vol. 32, no. 3, Apr., pp. 7-11, 30-1.


Text Box: In the interest of the society and future generation, onus is on the proponent of these construction activities to hand over this land (acquired clandestinely) to the Government of Karnataka to develop as children’s park. This would also help in showcasing the commitment of citizens and administrators of Bangalore towards maintaining inter and intra generation equity.

 

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