For over five years now, residents of Manali New Town and its neighbouring areas hardly have used groundwater and completely rely on piped or street supply as the groundwater in the localities near the Kosasthalaiyar has turned saline due to seawater ingress into the river bed.
In a bid to arrest salinity ingress caused by seawater gushing for over seven km into the river bed, a check dam is proposed to be built at Idayanchavadi across the 150-metre-wide Kosasthalaiyar. As the river bed is dry for most of the year, seawater gushes into the dry bed from the Ennore estuary. This, in turn, has permeated into groundwater up to Subbareddypalayam.
The groundwater turned saline nearly a decade ago and many people have opted out of agriculture, say residents. P. Palani, secretary of Manali New Town Residents Welfare Association, recalled that residents used groundwater for cooking and drinking until the late 1990s. But, as the river became dry, it ended up carrying more of seawater.
“We are located three km from the estuary. Earlier, the neighbourhood used to have much greenery with vegetable and paddy cultivation. But groundwater salinity has affected over 30 villages. We have been demanding a check-dam for several years now,” he said.
Preliminary work
Meanwhile, the Water Resources Department has started preliminary work to construct a check-dam. On the other hand, the check-dam will also retain floodwater for some more months in the year for a few kilometres upstream and help groundwater recharge in areas such as Vellivayalchavadi, Napalayam and Kondakarai.
The department has also completed a soil test to check the feasibility of constructing two more check-dams in Bandikavanur and Pudukuppam near Karanodai across the Kosasthalaiyar river.
Check-dams would help in boosting agricultural activity in the neighbourhood and also arrest illegal sand mining in the river bed. As the river is dry for many months, illegal sand mining is rampant in the stretch. “It is essential to have check-dams at an interval of two or three km to prevent floodwater from draining completely into the sea completely and sustaining river flow,” he added.
Meanwhile, residents demanded that steps must be taken to restore the check-dam built by Chennai Metrowater in Jaganathapuram near Cholavaram.
