The Water Resources Department has started work to strengthen the 136-year-old Red Hills reservoir under a Rs 10.56-crore project that will be completed in the next three months, according to sources.
Sources told City Express that work to strengthen the reservoir, which is the city’s primary drinking source, started in January this year. The funds are being provided by the State government.
The work includes strengthening of the weir, filter arrangements on the slope of the bund, rock toe arrangement and minor repairs of shutters of the reservoir located in Ponneri Taluk of Tiruvallur district and one of the two rain-fed reservoirs from where water is drawn for supply to the city.
There are two masonry weirs in the reservoir. One is 178 metres long and the other is 220 metres long and 15 feet deep. The weirs are a barrier across the water body, designed to alter the flow characteristics. In most cases weirs take the form of a barrier, smaller than conventional dams, across a river, which causes water to pool behind the structure and allows it to flow over the top. Weirs are commonly used to alter the flow regime of the river, prevent flooding, measure discharge and help render a river navigable.
Sources said the strengthening of the weir will enhance the reservoir, which was built in 1876. The reservoir was originally a small tank with a capacity of 500 million cubic feet and two masonry weirs, built using locally available laterite stones, then functioned as surplus weirs to release excess water from the water body. During 1997, the storage capacity of the reservoir was increased to 3,300 million cubic feet and the depth to 21.20 ft to cater to the drinking water needs of Chennai.
Sources said that the reservoir provided 50 per cent of Chennai’s drinking water requirements. The project is significant to arrest leakage from the two surplus weirs, which are structures that allow excess water to flow out when the storage reaches its full tank level.
Currently, the city is dependent on four reservoirs – Poondi, Cholavaram, Red Hills and Chembarambakam. Veeranam supplements the water supply.