Dwindling population of two living microscopic organisms is the main reason
Even as the Cauvery delta eco-system gets degraded, the future looks extremely painful as far as drinking water is concerned.
One of the major aspects of the degradation is the dwindling population of two living organisms, which play a crucial role in potability of water, says Prof.K.V.Krishnamurthy, former head of department of botany, Bharathidasan University.
Two microscopic organisms — phytoplankton and zooplankton – that eat decaying organic materials help the pH value of water. Water could be deemed acidic or alkaline depending upon this value and potability is determined by this, he adds.
It is in the case of drinking water that civic associations like the Exnora International are worried.
Its advisor V.Ganapathi points out that exploitation of groundwater along the banks of the Cauvery and the Coleroon has become very high. “From 50 feet to 60 feet depth, even on the banks of the rivers, the depth of the bore wells has now touched 100 feet. This type of exploitation of aquifers, especially when there are no flows at all, is not sustainable,” he asserts.
Above all, the total quantity of water flowing in the rivers itself has come down. The Cauvery, which has seen more than 300 thousand million cubic ft (tmcft) during certain years, is now struggling to get 205 tmcft prescribed by the Cauvery River Disputes Tribunal.
“It is quite unlikely that we are going to get even that much of water this year,” he observes.
Besides, the flow in the rivers year-round has become a thing of the past. “Thus the quality of water will soon start going down. And potability is going to be a very big problem,” he laments.
The Coleroon (flowing from Upper Anicut up to Kollidam - about 180 km), which has been the flood carrier, has deeper aquifers than the Cauvery.
Thanks to over-exploitation of these aquifers, this water is not as potable as it used to be, he says.
S.Balachandran, Deputy Director, Bombay Natural History Society, points out that birds are the indicators of the health of the ecosystem. “If huge wetlands were to dry up due to the loss of inflows in the Cauvery\Coleroon it will have severe impact on the natural ecosystem,” he asserts.
While natural bird sanctuaries like Point Calimere are on the coastline, they have either sea water or brackish water. The Cauvery is the only fresh water source in the neighbouring areas.
If neighbouring areas are cultivated, birds use these fields for roosting, nesting and feeding.
Apart from the local bird population, migratory birds use these wetlands. For these birds, the wetlands are sort of a buffer zone. And they collect food from some other places.
“If drought persists till October, migratory birds might shun these fields,” he cautions. He admits that Point Calimere bird sanctuary might get affected and other sanctuaries, including Karaivetti, Vaduvur (both used by the migratory birds for roosting), Udhayamarthandapuram and Kallaperumbalur, which are inland sanctuaries, would also suffer seriously.
As sand is indispensable for retaining the capacity of the river to hold water, social activists led by advocate R.Nandakumar have sought a ban on sand quarrying in the Cauvery and the Kollidam river from Karur to Nagapattinam.
According to Mr.Nandakumar, not only illegal quarrying of sand is taking place in Tamil Nadu but also illegal sand quarries have been set up.
The quarries functioning in the Cauvery are more than five hectares. “It is not only hidden from the eyes of the public but also from the eyes of the court,” he alleges.