Environmental experts said the plantation of 370 hectares of mangroves around the Navi Mumbai airport site to compensate for the mangroves that would be destroyed for the project would not be easy.
The environmental clearance specified that 678 hectares of mangroves would have to be in place before the airport work begins. About 370 hectares of mangroves would be planted, while the rest already exist and will be preserved.
“To plant mangroves over 370 hectares, you require an investment for the next 30 years both in terms of money and monitoring. A project of this scale would need a budget of Rs 40 crore, but only a fraction of that has been allocated,” said a marine biologist, who did not wish to be named.
Around 98 hectares of mangroves will have to be chopped for the two runways. To compensate, City and Industrial Development Corporation will develop a new 60-hectare mangrove park, adding to it 310 hectares of mangroves to the north-east of the airport site. Bombay Natural History Society has been given the task of mangrove plantation. The mangrove park is likely to have a bio-diversity park and a lagoon.
According to experts, the plantation will have to be done taking into account that 60% to 70% of the mangroves will die every year and will have to be planted afresh in stages. The budget will have to be drawn up accordingly.
For instance, to ensure that 100 hectares of mangroves survive, you have to plant saplings over an area of 1,000 hectares. This means planting one lakh saplings. Assuming a 50% mortality rate in the first year, you would have to plant 50,000 saplings the following year.
“Scientists will have to work backwards keeping mortality in mind. The newly-planted mangroves will have to be looked after for at least 20 years before they start self-sustaining,” said another expert.