Authorities said the reservoirs including Chembarambakkam were under a 'constant watch' and people in low lying areas were being brought to safe shelters.
The deep depression over southwest Bay of Bengal moved west-northwestwards and intensified into a cyclonic storm 'Nivar' and lay about 410 km off Puducherry and 450 km from here.
The Central Water Commission (CWC) has asked authorities to maintain a vigil in reservoirs during high-intensity rainfall as catchments are nearly saturated and there could be spillover from Chembarambakkam reservoir.
CWC Chennai said there could be flood-like situation in rivers downstream.
"Vigil has to be kept in reservoirs during high-intensity rainfall as catchments are nearly saturated. Further intense rainfall will lead to Chembarambakkam reservoir leading to spill and flood-type situation in rivers downstream," Central Water Commission, Chennai said.
Union Cabinet Secretary Rajiv Gauba today chaired a meeting of the National Crisis Management Committee (NCMC) to review the status of the impending cyclone through video conferencing with the Chief Secretaries of Andhra Pradesh, Tamil Nadu and Puducherry.
The Chief Secretaries briefed the NCMC about their preparedness and mentioned that the authorities are fully prepared to meet any eventuality. They also informed about the coordination with the NDRF and other agencies to meet this challenge.
The deep depression over Bay of Bengal intensified into a cyclonic storm, 'Nivar' and it is likely to intensify further into a severe cyclonic storm and cross the Tamil Nadu and Puducherry coasts on November 25, the Met department said on Tuesday.
(With inputs from ANI)