Nature Based Solutions : EAST KOLKATA WETLANDS

URBAN MANAGEMENT CENTRE

Administrative Training Institute

Government of West Bengal, INDIA

Kaushik Ghosh Assistant Professor

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Kirkpatrick Sale in a study says “A city of 1 million, it has been calculated, takes in 9500 tons of fossil fuel, 2000 tons of food, 625000 tons of water and 31500 tons of oxygen every day and puts out 500,000 tons of sewage, 28500 tons of carbon dioxide and great quantities of other solid liquid and gaseous waste “

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Location Between latitudes 22º25’ to 22º40’ N and longitudes 88º20’ to 88º35’ E Hot and humid climate throughout the year Average rainfall of 1600 mm (90 % between June to October) The wetland is bordered by the city of Kolkata to the West, Salt Lake City

to the North-West and the New Town Rajarhat to the North-East.

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Waste Recycling Region Area 125 sq. kms [12,500 hectares]

Wetlands 8.5 feet below city highest point

Prompted construction of a series of sewers and pumping stations

Presently 254 functioning aquaculture ponds (Bheries).

The solid waste dumping area on the western periphery of the wetlands were converted to horticulture since 1876.

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Categories of Land Use

46,82% 37,75%

4,82% 10,61%

Sewage-fed fishery activities area 5852.14 ha

Agricultural area 4718.56 ha

Productive garbage farming area 602.78 ha

Urban and Rural settlement area 1326.52 ha

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72% 27%

1%

Private Ownership

Fisherman's Cooperatives

State - Owned

Ownership of Fish Farms

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Raw material : SEWAGE Kolkata Municipal system generates

about 750 million liters of sewage fed waste water daily.

The underground trunk sewer lines of Kolkata city are linked with 17 pumping stations all located on the eastern fringe.

The trunk drain was designed to take the discharge towards a tidal river on the eastern side, then to the Bay of Bengal.

Almost 600 million litres of sewage is channelised into the EKW everyday.

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Bantala Lockgate

The most crucial regulator

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Wastewater Distributaries

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• Wastewater will pass through a water hyacinth tank where some amount of heavy metals and suspended solids may be absorbed from the wastewater before this water is allowed to enter into the fish ponds.

• Process is called RHIZOFILTRATION. Here the plant roots act as bio-curtains or bio-filters for the passive remediation of wastewater.

Inlet System

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Urban waste water is supplied by the Municipal corporation is routed through a series of small inlets, each managed by a fishery cooperative.

A parabolic gate separates the wetland from the wastewater like a sieve.

Treated Sewage is channeled into initial ponds through a parabolic gate to prevent fish from swimming back into the oxygen less urban waste water. Water is cleaned in less than 20 days.

Wastewater Treatment & Aquaculture

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Early morning fishing

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Going to market

Fish from farms is being transported in Hundies to the market

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Fish Auction Market

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2 to 4 times higher production than that obtained from normal ponds and their production cost is also unmatched by any other freshwater fish ponds of this country.

Fresh water fishes like Indian Major Carps, Silver Carp, Grass Carp, Common Carp, Tilapia, Nilo-tica etc.

Fishery Effluent to Paddy Field

• Sewage is pumped by Farmers for Agriculture

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Co-Recycling in Dhapa

Garbage Farming at Dhapa produces 150 MT of vegetables daily

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Desilting Waterbodies

• Pond Bed is dried up • Canals are desilted

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Outlet of EKW

Bagjola Canal – an important outlet of EKW.

Naturally treated wastewater flows out to the Kulti-Gong river

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Harmonious co-existence

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Traditional knowledge

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Resource Recovery practices in EKW

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Threat of Urbanisation

Heavily urbanised periphery is a major management challenge

Land use conversion is a threat

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Former Chief Environment Officer, Govt. of West Bengal

Special Advisor, International Union for Conservation of Nature (IUCN)

Recipient of Global 500 Award by UN for enviromental achievement

In 2016, he was awarded the prestigious CEM Luc Hoffmann Award at the World Conservation Congress in Honolulu, Hawaii

Dr. Dhrubajyoti Ghosh : Wetlands Warrior (1947-2018)

“the nature park is a tutorial ecosystem for the rest of the world, especially the low lying cities in the tropical regions like Dhaka, Mumbai, Jakarta and Bangkok.”

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• RAMSAR Site, 2002, Wetland of International Importance • EKWMA (Conservation) Act 2006 • WORLD WETLANDS DAY, FEB 02

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Photo/Data Source & Credit: 1. Dr. Dhrubajyoti Ghosh : Slide-2,4,6,8,9,10,12,13,14,15,16,17,19,20,22

2. Prof. Santosh Ghosh : Slide-11

3. Patrick Barkham : Slide-23

4. East Kolkata Wetlands Newsletter, Nov 2010, Vol-1, East Kolkata Wetlands Management Authority & Wetlands International-South Asia. Photo credit: Subhajeet Debnath : Slide-1,2,4,5,7,12,13,15,16,18,22,24,26

5. Kolkata Wetlands Management Authority Report (2013-14 to 2015-16), Environment Department, Govt. of West Bengal : Slide-5

6. Sewage-fed Fisheries under Private Ownership in the East Kolkata Wetlands: A Case Study Dr. Suranjana Bannerji; International Journal of Advancements in Research & Technology, Volume 3, Issue 6, June-2014 : Slide-6

7. Banerjee, Sarmila and Dey, Debanjana (2017) "Eco-system Complementarities and Urban Encroachment: A SWOT Analysis of the East Kolkata Wetlands, India," Cities and the Environment (CATE): Vol. 10: Iss. 1, Article 2. : Slide-3,21

8. P. Amerasinghe (IWMI), D. Dey (SAFE), R. Gopichandran (DST), B. Kayal, V. Sadamate, S. Kumar and M. McCartney (IWMI) (2014), Workshop on institutions for ecosystem services, IWMI; Institutional mechanisms to conserve ecosystem services in the East Kolkata Wetlands (EKW): A case for the bio-rights approach : Slide-3,5

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Lessons in Sustainability

1. Fish and vegetable production and supply providing food security and nutrition. Fertiliser and pesticides are not required.

2. Recycling process of sewage waste water fed aquaculture with recycling of solid waste controls pollution and improves environment with more oxygen. It protects bioregion.

3. It provides employment, income for other causal workers and provide better living standards.

4. Preservation of biodiversity and east Kolkata wetlands provide a blue and green buffer to between urban and rural areas.

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Lessons in Sustainability

5. It helps ground water recharge and monsoon flood control due to climate change.

6. Improved irrigation and agriculture

7. Indigenous process and recycling instead of expensive wastewater treatment Plants can purify waste water with exposure to sun in photosynthesis process with phytoplankton.

8. It is cost effective, it helps recover materials.

9. It provides recreation, ecotourism etc.

10. Ecosystem services of Wetlands are more valuable compared than rivers, lakes, forests and grasslands.

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… if only we took a walk !

Thank you very much !!

98304 19290

ghosh.architect@gmail.com

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