Eco-Restoration of Adyar Estuary (300 acres) Phase II
Eco-Restoration of Adyar Estuary (300 acres) Phase II
LOCATION
Adyar River originates from surplus course from Chembarabakkam Lake in Kancheepurum District and flows in the southern parts of Chennai. The river runs about 42 kilometers west to east and meets the Bay of Bengal in Adyar. Adyar estuary, the point at which the river meets the Bay of Bengal lies between Santhome beach in the north and Elliots Beach in the south. The estuary region from Thiru Vi Ka Bridge to the river mouth and the creek region from Santhome Causeway to river mouth spread over an area of about 300 acres.
INTERVENTION
In order to address ecological issues and to implement long term measures as the holistic solution to restore the ecology of the Adyar estuary, a Master Plan and Detailed Project Report for Ecological Restoration of Adyar Creek and Estuary was prepared in 2008. The objective of eco-restoration of Adyar estuary and creek is to achieve and maintain best feasible water quality in its riverine and estuarine stretches and thus provide an opportunity to bring back the natural (endemic) life forms that interact with abiotic elements and create a healthy ecosystem. Improving and maintaining water quality to a level that can support a balanced population of phytoplankton, zooplankton and nektons is the real way forward towards the stated objective.
Eco-Restoration of Adyar Estuary (300 acres)
In continuation of the Eco-Restoration of Adyar creek in 58 acres as detailed above, the adjoining estuary with an extent of 300 acres was taken up by the Government.
The eco-restoration works were taken up with the components of bund stabilization, continuous removal of debris and plastics and removal of invasive species of Prosopis juliflora, which has now enhanced the tidal interaction and increased the water spread in the creek and estuary. Mangroves and Native riverine vegetation were planted to rejuvenate and enhance the biodiversity of riverine ecosystem.
Objectives of the Eco-Restoration
- To achieve and maintain best feasible water quality in its riverine and estuarine stretches and thus provide an opportunity to bring back the natural (endemic) life forms that interact with abiotic elements and create a healthy creek and estuarine ecosystem.
- Improving and maintaining water quality to a level that is conducive to supporting a balanced population of phytoplankton, zooplankton and nektons.
RESTORATION ACTIVITIES
IMPROVING WATER CARRYING AND HOLDING CAPACITY
A onetime cleanup by removing debris, plastics and sludge in the creek region and river mouth of project area was removed to improve the flood carrying capacity of the channel and to improve the dilution by increasing the volume of water held in the estuary and creek, specifically during the low tides. It had broadens the channel to 400m for tidal exchange. Removed exotic and invasive species like Prosopis juliflora, followed by bund stabilization.
MEASURES FOR ENHANCED TIDAL EXCHANGE
Enhanced tidal exchange along with the control of organic pollution was identified as an important aspect of the eco-restoration. This necessitates opening of the mouth of Adyar estuary throughout the year. Sustained opening of the mouth will also facilitate the re-colonization of the endemic aquatic fauna. The pattern of littoral drift along the coast is the primary cause for the formation of the sand bar at the mouth of the Adyar estuary causing complete/partial blockage. The sediment deposit at the Adyar river mouth due to the northward littoral drift, especially during the months of May to August being the primary reason for closure of Mouth. The solution to opening of the mouth lies in control of sediment in the sea water current flow crossing the river mouth and/or following a maintenance scheme that removes the sediments as those gets built up during the months of high littoral drift towards north.
HABITAT RESTORATION
The floral and faunal restoration are the other two major elements towards achieve the objective. The improvement in water quality allows the natural process of regeneration of flora and fauna. Removal of Prosopis juliflora from the islands and edges with the gradual, Replacement by native species, Plantation of Mangroves at low-level island adjacent to Adyar bridge and Regeneration of mudflat vegetation were envisaged and about 57,000 mangroves and 35,000 terrestrial saplings were planted. Renewable and alternate energy source i.e., 180 numbers of solar powered lights were installed;
SHORELINE PROTECTION AND STABILIZATION
Bioengineering solution provides long-term benefits to the shoreline and water quality, stabilizes the bank and shoreline while improving fish and wildlife habitat. This method works well in combination with structural methods; the combination is described as a biotechnical installation. Bioengineering alone is generally not applied on steep slopes and usually requires some shaping of a slope as part of the installation. Bund stabilization and fencing was completed for a length of 2350m;
IMPROVING WATER CARRYING AND HOLDING CAPACITY
A onetime cleanup by removing debris, plastics and sludge in the creek region and river mouth of project area were taken up to improve the flood carrying capacity of the channel and to improve the dilution by increasing the volume of water held in the estuary and creek, specifically during the low tides. It had broadened the channel for tidal exchange.
CONTINUOUS MONITORING OF PROJECT AREA
An estuary is a sensitive ecosystem and needs constant monitoring of the project area during the eco restoration process as well as post-restoration, to improve people’s interactions with the estuary and the river. The existing access into the estuary is extremely poor and hidden from the public and this has been the major reason why the open spaces of the estuary have been misused. A pathway was created for continuous monitoring of the project area.
All proposed restoration activities have been completed in total and regular maintenance work is being carried out.
