Nagari river in Tiruvallur district limits is getting inflow from a dam upstream in Andhra Pradesh.
However, water must be released consistently for the flow to reach Poondi reservoir, one of the city’s main sources of drinking water, according to the Water Resources Department.
It may be recalled that a minimal quantity of surplus water was initially released into the river on Saturday from Ammapalli dam, Krishnapuram village, located in Andhra Pradesh.
WRD officials said about 600 cusecs (cubic feet per second) was again released between 10 p.m. on Sunday and 4 a.m. on Monday and was later stopped.
The water had travelled for 12 km up to the Pallipet bridge on Monday and was expected to reach Nallatur check dam near Tiruttani by Monday night. Flood warning for surrounding villages was issued by the Tiruvallur Collectorate as a precautionary measure.
Surplus water from Nagari needs to travel another 15 km and may take a few more days to reach Poondi. The reservoir mainly gets inflow from the Nagari and Nandi rivers.
From downstream of Poondi reservoir, the waterway flows as Kosasthalaiyar.
Of the Nagari’s total depth of nearly 1.8 m, water is currently flowing at 0.3 m. The portion of the river near Pallipet can carry up to 30,000 cusecs. “Water needs to be released regularly for the flow to reach Poondi reservoir. There was an inflow of 160 cusecs into the lake after overnight rainfall on Monday. This added 11 million cubic feet of water. However, it was from local catchment areas which received 3 cm of rainfall,” the official added.
Forecast of rain
The Meteorological Department has forecast that many parts of the State would get light to moderate rainfall for two days. S. Balachandran, Deputy Director General of Meteorology, Chennai, said there was a shear zone of easterlies and westerlies in the mid-atmosphere over Tamil Nadu.
An upper air circulation already exists and may develop into a low pressure area over the north Bay of Bengal by Tuesday. This may also strengthen westerly winds and bring thunderstorms over the State.
Kancheepuram, Tiruvallur, Tiruppur, Vellore and Tiruvannamalai will receive rainfall.
A few places in districts along the Western Ghats such as Coimbatore and the Nilgiris are likely to receive heavy rain. Chennai may experience light rain till Wednesday.