3-year study to understand impact of undersea tunnel for bullet train on migratory birds

MUMBAI: A three year study on migration pattern and habitat use by birds wintering in the Thane Creek will soon be undertaken by the Bombay Natural History Society.
The study is to understand the impact of the 7-km undersea tunnel in the Thane Creek at a depth of 20-25 metres on the mudflats and the birds. Around 200 birds of 20 different species that flock to the Thane Creek Flamingo Sanctuary (TCFS) will be tracked through satellite transmitters for the study. It is for the first time that a study is being carried out on a large scale. A Memorandum of Understanding (MoU) was signed between the BNHS and the Mangrove Foundation that is funding the study on Monday.
The study is part of the mitigation plan for the Mumbai-Ahmedabad bullet train project. The Environment Clearance granted by the union ministry of Environment, Forests and Climate Change mandated a mitigation plan for the undersea tunnel to be dug at a depth of 25 metres in the Thane Creek. The 7-km undersea tunnel in the Thane Creek will be built between the underground station at Bandra Kurla Complex and Shilphata in Kalyan. The mitigation plan has been prepared by the Mangrove Cell which was approved by the principal chief conservator of forests and the chief wildlife warden, Maharashtra State in May last year. Besides the study, the mitigation measures include restoration of mangroves, removal of solid waste and identification of alternate bird habitat sites.
The National High Speed Rail Corporation Limited (NHSRCL) has deposited Rs 9.92 crore for the implementation of the mitigation plan. Of this Rs 5.29 crore has been allocated to this study. The NHSRCL had appointed CSIR-Central Institute of Mining and Fuel Research (CIFMR) to carry out a study on the impact of the undersea tunnel on the birds and the mudflats that are the feeding grounds for these migratory birds. “The study showed tunnelling can be carried out without any disturbances to the mudlflats in the creek at a depth of 20-25 metres. However, we have decided to carry out a large-scale study to see if anything at all happens and the change in movement of birds,” said an official.
A 10-year study is already underway to study the impact of the Mumbai Trans-Harbour Link on migratory birds including flamingos. Officials said for sometime the birds around the area had reduced but now they are seen feeding on the mudflats at Sewri though the construction is underway. “The exact impact of the construction and the movement of vehicles on the birds will be known when the study is completed in 2027,” said an official.
Nearly 2.5 lakh birds migrate to the TCFS during winter and spend nearly five to six months here. Virendra Tiwari, additional principal chief conservator of forests, Mangrove Cell said in a region like Mumbai where development projects are inevitable it is important to have a clear understanding of the intensity of use of Thane Creek and its adjoining areas so that appropriate conservation measures can be taken.
Bivash Pandav, director, BNHS said satellite transmitters (telemetry) generates useful data to determine migratory routes, critical stopover sites and anthropogenic barriers to migration.