Rapid Urbanization Threatens India's Kolkata Wetlands Ecosystem

Key Highlights :

1. Wetlands just outside India's Kolkata have for generations provided tons of food daily and thousands of jobs as they filter sewage through fish ponds—but rapid urbanization is threatening the ecosystem.

2. Conservationists warn that pollution and strong-arm land grabs are putting a lifeline for the megacity's 14 million residents at risk.

3. "We are destroying the environment," said Tapan Kumar Mondal, who has spent his life farming fish in the ingenious system of canals and ponds stretching across about 125 square kilometers (48 square miles). "The population... has increased, there is a pressure on nature, they are ruining it," 71-year-old Mondal added.

4. Listed as a wetland of global importance under the United Nations Ramsar convention, the waters offer natural climate control by cooling sweltering temperatures—and act as valuable flood defenses for low-lying Kolkata.

5. But Dhruba Das Gupta, from the environmental group SCOPE, said that short-sighted building development was encroaching on the wetlands. "The wetlands are shrinking," said the researcher, who is trying to finance a study of what is left of the waters.

6. Every day, 910 million liters of nutrient-rich sewage flow into the wetland, feeding a network of about 250 hyacinth-covered ponds. "Sunlight and the sewage create a massive plankton boom," said K. Balamurugan, chief environment officer for West Bengal state, explaining that the microorganisms in the shallow fish ponds feed rapidly growing carp and tilapia. Once the fish have had their fill, the water runoff irrigates surrounding rice paddies and the remaining organic waste fertilizes vegetable fields. "The sewage of the city is being naturally treated by the wetlands," Balamurugan said, giving them the nickname the "kidneys of Kolkata".

7. The community-developed system was created by "the world's foremost connoisseurs of wastewater wise use and conservation", according to its UN Ramsar listing, which also warns it is under "intense encroachment stress of urban expansion".

8. The wetlands system processes about 60 percent of Kolkata's sewage free of charge, saving the city over $64 million a year, according to a 2017 University of Calcutta study.

9. Farms in the wetlands provide about 150 tons of vegetables daily, 10,500 tons of fish annually and employ tens of thousands of people, the Ramsar listing estimates.

10. For Kolkata, on the vast delta where the Ganges River meets the Indian Ocean, the wetlands also provide flood defenses for a city facing rising sea levels due to climate change.

     The wetlands just outside India's Kolkata have been a lifeline for the megacity's 14 million residents for generations. These wetlands have provided tons of food daily and thousands of jobs as they filter sewage through fish ponds. But rapid urbanization is threatening this vital ecosystem. Conservationists are warning that pollution and strong-arm land grabs are putting the wetlands in danger.

     Tapan Kumar Mondal, who has spent his life farming fish in the wetlands, said, "We are destroying the environment. The population has increased, there is a pressure on nature, they are ruining it." Listed as a wetland of global importance under the United Nations Ramsar convention, the waters offer natural climate control by cooling sweltering temperatures and act as valuable flood defenses for low-lying Kolkata.

     Dhruba Das Gupta, from the environmental group SCOPE, said that short-sighted building development is encroaching on the wetlands. "The wetlands are shrinking," he said. Every day, 910 million liters of nutrient-rich sewage flow into the wetland, feeding a network of about 250 hyacinth-covered ponds. This sewage creates a massive plankton boom, which feeds rapidly growing carp and tilapia. Once the fish have had their fill, the water runoff irrigates surrounding rice paddies and the remaining organic waste fertilizes vegetable fields.

     The wetlands also provide flood defenses for a city facing rising sea levels due to climate change. K. Balamurugan, chief environment officer for West Bengal state, said, "These wetlands are acting as a natural sponge, taking the excess rainwater." Dhrubajyoti Ghosh, a late ecologist who played a key role in the 2002 Ramsar submission, called Kolkata an "ecologically-subsidized city". The wetlands system processes about 60 percent of Kolkata's sewage free of charge, saving the city over $64 million a year.

     Unfortunately, industrial effluent is tainting natural systems, threatening food production. Fish farmer Sujit Mondal said that production has reduced because of "murky water". About 95 percent of the wetlands are in private hands. As land prices surge, environment officials have pleaded with people not to fill in the fish ponds to create new building space. But residents say village councils are being bribed by land-hungry developers. This leads to huge loss of productive space, and destroys the ecosystem services offered by these wetlands.

     It is clear that rapid urbanization is threatening the wetlands just outside India's Kolkata. Without these wetlands, the megacity's 14 million residents will lose a vital lifeline. Conservationists are pleading with people to not fill in the fish ponds and preserve the wetlands. If we do not act soon, we will lose this valuable ecosystem and the services it provides.

Continue Reading at Source : phys