"The embankment reconstruction work has mostly been done by the locals who are untrained and inexperienced. Thus, there always remains a question mark on the quality of the freshly-built embankments on the islands," Tushar Kanjilal of the Tagore Society for Rural Development said.

He said that nearly 778 km of the total 3,500 km of natural embankments in the Sundarbans were completely washed away in the cyclone Aila that hit the mangrove-infested deltaic region last year.

Even during full-moon high tides, the embankments get damaged and the saline water enters the human habitation, causing serious damage to agricultural fields, he said.

According to environmental experts, the saline water, which flooded most of the islands in Sundarbans after cyclone Aila, had impacted the fertility of the agricultural land as they have virtually turned infertile for the next three-four years.

More than 900,000 houses, a majority of them in the Sundarbans, were damaged in the disaster in May last year.

Subhro Sen, senior programme officer of the World Wide Fund For Nature (WWF), told IANS: "We have seen, while closely working with the villagers, that most parts of the embankments were reconstructed with concerted human effort. But the quality is still a question as those were rebuilt with sand, soil, bamboo tricks and bricks."

According to Kanjilal, "In monsoon, the chances of such damage become higher as the water level generally flows much above the safety level and it can easily destroy the weak embankments."

"It's true that the villagers enthusiastically took part in the embankment reconstruction process. But that is not enough. They were not constructed scientifically and cannot stand any disaster," he said.

Kanjilal, who was for 30 years the headmaster of a high school in Rangabelia, a remote island village in the delta, piloted the Rangabelia Comprehensive Rural Development Project for the social and economic betterment of people living in the Sundarbans.

He also runs a welfare organisation, the Tagore Society for Rural Development, in the Sundarbans and has been working on various social and environmental projects in the deltaic zone since 1967.

He said that in some parts of the islands the progress of embankment reconstruction was "really slow".

Located in Kolkata's neighbouring north 24 Parganas and South 24 Parganas district, the Sundarbans has a vast area covering 4,262 sq km, including a mangrove cover of 2,125 sq km, in India alone. A larger portion lies in Bangladesh.

The deltaic belt -- a vast tract of forest and saltwater swamps -- is located at the lower part of the Ganges delta, extending 260 km along the Bay of Bengal from the Hooghly river estuary in India to the Meghna river estuary in Bangladesh.

Environment Minister Jairam Ramesh, while addressing an international workshop on climate threat to the Sundarbans recently, said the cabinet had already approved the 'Integrated Coastal Zone Management Project' (ICZMP), under which West Bengal will get Rs.300 crore and the Sundarbans will get the bulk of the project over a period of next five years.

According to the 13th Finance Commission recommendations, the central government has also decided to give a special grant of Rs.450 crore to be spent over the next five years for strengthening and armouring the embankments of Sundarbans islands -- the world's largest mangrove forest.

The minister said the government had appointed an expert team -- Indian Network for Comprehensive Climate Change Assessment (INCCCA) -- comprising 128 research institutes, which is doing extensive assessment on critically vulnerable coastal areas across India, of which the Sundarbans is one of the most important regions.

The first report will be published in November.