Modi had earlier spoken to Tamil Nadu Chief Minister Jayalalithaa to promise all possible support.
For the first time in over 40 years, the water has risen rapidly on the river breaching the road and the Maraimalai Adigal bridge in Saidapet cutting the arterial Anna Salai (Mount Road), rendering it out of bounds for motorists.
Rains abated in Chennai today giving relief to people tormented by the heavy downpour of the last three days but excessive discharge of water last night from Chembarambakkam lake on the outskirts flooded new areas of the city threatening to uproot people from their homes.
The fresh flooding of the streets in the heart of the city in areas like Kodambakkam and T.Nagar and Ashok Nagar has been caused by the release of an estimated 30,000 cusecs of water from the Chembarambakkam lake, one of city's source of drinking water.