The Yamuna is flowing over two metres above the danger level, crossing the 207-metre mark for first time in 32 years and submerging several low-lying areas near Delhi.
Authorities said the water level is expected to go up further and may touch 207.30 metres by Thursday afternoon but insisted that all arrangements have been made to deal with the situation.
Garhi Mandu, Usmanpur Pusta, Jagatpur Village and Shastri Nagar, Yamuna Vihar, Madanpur, Sonia Vihar, Nigambodh, Jaitpur, Tibet Market and Yamuna Bazar have been submerged.
"The water level in Yamuna touched 207.06 metres at 8 pm on Wednesday, which is 2.23 metres above the danger mark of 204.83 metres. It will keep on rising and is likely to touch 207.30 metres on Thursday," Chief Engineer in the Flood and Irrigation Department V P S Tomar said.
Delhi witnessed massive floods in the year 1978 when water level in Yamuna had touched 207.49 metre.
The water level in Yamuna has gone up after Haryana released 7.5 lakh cusec of water into it on Monday, the highest discharge in last 100 years on a single day. The neighbouring state had released a total of 6.53 lakh cusec of water into the river on Sunday.
Fearing a flood-like situation, Delhi government has shifted people living in low-lying areas to safer places.
"We are constantly monitoring the situation and everything is under control. We have already shifted people living in low-lying areas," Tomar said.
The government has shifted hundreds of people from Garhi Mandu, Usmanpur Pusta, Jagatpur Village and Shastri Nagar to relief camps. Over 3500 people who shifted to relief camps set up by the government following flood-threat last week, are already staying there.
In the last 40 years, the city had witnessed floods in 1967, 1971, 1975, 1976, 1978, 1988, 1995 and 1998 but the flood in 1978 was of serious nature as it had inundated many areas in the city. The water level in Yamuna had touched 207.49 metres then, flooding vast areas in east Delhi.
Railways on Wednesday cancelled 22 trains in view of the closure of the Old Yamuna bridge in Delhi and announced diversion of 65 other trains. The cancelled trains were mostly local trains, a Northern Railway spokesperson said.
He said 53 trains were terminated at various stations. The Old Yamuna Bridge, connecting east Delhi with the heart of the national capital, was shut for rail and road traffic on Tuesday after water level in Yamuna rose menacingly.