Invasive species of flora, such as wattle and eucalyptus, that have sprung up along the water spread area of the Emerald and Avalanche reservoirs could lead to further depletion of water level in the reservoirs, environmentalists have warned.
A combination of factors is said to have caused a dip in storage over the last few years in the two reservoirs that are key to water supply in the Nilgiris district and areas downstream.
While poor rainfall over the last few years, especially in the catchment, is cited as one reason, the other is intensive farming activity in the areas surrounding the dam.
Farmers are said to have tapped into the groundwater resources and also the streams that flow into the reservoirs. And, the invasive flora species have added to the problem.
B. Sumathi, a local resident, says the Emerald Dam last filled up over five years ago.
The water level had receded since then. “We noticed that the water level began receding and the trees surrounding the reservoir soon began to make inroads, springing up in the areas that were once submerged,” she said.
Restoration ecologist, Vasanth Bosco, told The Hindu that the spread of invasive species of trees could lead to a fall in the storage level.
“There could definitely be an impact, especially as the trees are still young and are in the growing phase. When they require plenty of water to grow, the trees will make use of available water resources nearby,” he said. Either the Forest Department or Tangedco should remove the young trees before they grew bigger and guzzled water from the reservoir.
Environmentalists also pointed out that farming on the slopes along the reservoirs was causing top soil erosion into the water storage area.
The silt that got deposited in the reservoirs reduced their storage capacity.
On many local residents also raising crops, Tangedco officials said the expected rain in the coming weeks would submerge the areas encroached upon for farming.