The Palar river, known for remaining dry ordinarily, has been witnessing historic flows, thanks to heavy rainfall in its catchment, including parts of Andhra Pradesh.
At 5 p.m. on Saturday, the river witnessed the flow of 1.56 lakh cubic feet per second (cusecs), as recorded at the Vayalur checkdam in Chengalpattu district. The river joins the sea downstream the checkdam.
Friday saw a rapid rise in flow from 43,535 cusecs at 6 a.m. to about 87,880 cusecs at 3 p.m., and about 1.65 lakh at midnight. Such flows are considered uncommon.
Over 100 years ago, the river had registered a six-digit flow, an official of the Water Resources Department said.
Originating from the Nandi Hills in Karnataka, the Palar flows down to Tamil Nadu through Andhra Pradesh. Of its total length of 348 km, 93 km lies in Karnataka, 33 km in Andhra Pradesh and 222 km in Tamil Nadu. The river, having seven tributaries, enters Tamil Nadu near Vaniyambadi. It covers many important towns such as Vellore and Kancheepuram.
From November 10 to 20, about 37 thousand million cubic feet (tmc ft) of water drained into the sea through Vayalur checkdam. This is equivalent to one-and-a-half years’ requirement of Chennai’s water supply.
As on date, Chennai Metrowater supplies about 970 million litres a day to the city and its added areas. Even though the monthly requirement comes to about one tmc ft, an official, looking after the affairs of Chennai Metrowater, said one had to take into account evaporation and seepage losses, which came up to 40%. Going by this calculation, Chennai requires around 20 tmc ft a year to sustain the present level of water supply throughout the year, the official said.