Abundant rainfall this month has brought heavy flow in Cooum river and also filled check dams across its unpolluted portion. Considerable flow in the river has also helped flush out stagnant sewage in the urban stretches.
Officials of the Water Resources Department (WRD) said surplus water from Kosasthalaiyar river was transferred to the Cooum through a link canal running from the Poondi reservoir. This generated a flow in the river, most of whose stretches were otherwise dry till early this month. Floodwater from the Kesavaram anicut and Cooum tank augmented the flow.
Korattur anicut full
The recently-renovated Korattur anicut, which was a British-era storage structure built with regulator arrangements, has become full and is surplusing since Sunday. Five check dams across the river, including in Pudumavilangai and Putlur, are now full, and a minimum of 130 million cubic feet (mcft) of water has been stored so far.
The river would have carried about 2,000 cubic feet per second (cusecs) out of its capacity of 25,000 cusecs in its suburban portion. There will be inflow in the check dams at least till February.
This would ensure groundwater recharge in at least 50 villages along its course and help in irrigation, officials said. Moreover, it diluted the stagnant sewage and cleaned the river in some parts of Putlur and downstream of Thiruverkadu up to city limits.
Officials noted that once the proposal to build another check dam across the river at Sorancheri is implemented, additional floodwater can be stored in the Cooum.
Outflow increased
Meanwhile, discharge from three city reservoirs, including Chembarambakkam, was increased again on Tuesday. Officials said the amount released had increased as the water levels had reached close to full, and in anticipation of more inflow because of a heavy rain forecast.
About 1,000 cusecs were let out from the Red Hills and Chembarambakkam reservoirs on Tuesday.
Water level at Chembarambakkam now stands at 22 feet against its full capacity of 24 ft. Moreover, surplus water released into the Kosasthalaiyar from the Poondi reservoir has also been increased from 6,000 cusecs to 7,000 cusecs as its level is one feet lower than its capacity of 35 ft.
The fifth reservoir created at Thervoy Kandigai Kannankottai is also full this monsoon.