Kolkata: India and Bangladesh must collaborate to facilitate and maintain a flow of fresh water round the year to save the Sunderbans mangrove ecosystem, scientists said here Saturday.
Sunderbans is the world's largest mangrove forest and home to the endangered Royal Bengal tiger. More than two-thirds of the forest lies in Bangladesh and the rest in West Bengal.
"We need a definite bilateral collaboration to save this joint ecosystem. The two countries should collaborate to maintain round the year flow of a sustainable supply of fresh water to maintain the Sunderbans ecosystem," Sugata Hazra, director of the School of Oceanographic Studies (SOS) at Jadavpur University, said here.
He was discussing the key recommendations and findings of a project - 'Ecosystem For Life: A Bangladesh-India Initiative' - on environmental flow assessment methodology for the Sunderbans ecosystem, a part of the International Union for Conservation of Nature.
It was carried out by a joint research team from India and Bangladesh.
The team comprised SOS Kolkata, Indian Institute of Technology (IIT) Roorkee and Centre for Environmental and Geographic Information Services (CEGIS), Dhaka.
The pilot study centred on evolving a holistic methodology of assessment of environmental flows or e-flow.
E-flow means the quantity, timing and quality of water flows required to sustain fresh water and estuarine ecosystems and the human livelihood and well being that depend on these ecosystems.
Sunderbans, a Unesco world heritage site, is known for its exceptional biodiversity in flora and fauna with as many as 334 plant species and 693 species of wildlife.
These include 49 mammals, 59 reptiles, eight amphibians, 210 white fishes, 24 shrimps, 14 crabs and 43 molluscs.
Carried out in two spots in the region - Swarupganj on the Hooghly river and Majdia on the transboundary Ichamati river - the study took into consideration the required flow for four indicators - Gangetic dolphins, Sundari trees, Hilsa migration and navigation.
According to Hazra, as per the methodology presented, if Sunderbans is charged with 507 cubic metre per second (cumec) of fresh water and the Hoogly with 1,200 cumec then "the parameters can be maintained".
The approach used is the modified building block methodology that allows for simultaneously developing and testing the various components and helps break down a large and complex system into more manageable parts.
"The approach developed is found to be robust and efficient. The main issue is ensuring delivery of fresh water to the Sunderbans. We need more water in the lean period. Present level of flow is insufficient to maintain the ecosystem," Hazra said.
M.L. Kansal of the department of water resources development and management at IIT-Roorkee said if the designated amount of fresh water is pumped into the mangrove ecosystem, then flora and fauna could be stabilised to what it was two decades ago.
"Fresh water plays an important role in flourishing of the ecosystem. If we can jointly maintain the fresh water levels, then species could be revived to the level that it was 20 years ago," Kansal said, adding that more parameters could be included in the methodology.