The water level in the Yamuna here breached the warning mark of 204.5 metres on Monday following heavy rain in the upper catchment areas and is expected to rise further in the next two days, officials said.
The Delhi flood control room said the water level crossed the warning mark at 1 am on Monday and rose to 204.7 by 8 am.
It reported a discharge rate of 2,95,212 cusecs at 6 am from the Hathnikund barrage in Haryana, which is the highest so far this monsoon season. The flow rate was 2,57,970 at 7 am.
One cusec is equivalent to 28.32 litres per second.
Normally, the flow rate at the Hathnikund barrage is 352 cusecs, but the discharge increases after heavy rainfall in the catchment areas. The water discharged from the barrage normally takes two to three days to reach the national capital.
Authorities have not issued a flood alert yet.
Announcements are being made to caution people living in low-lying areas near the river banks about a further increase in the water level, East Delhi District Magistrate Anil Banka said.
"The water level is predicted to touch the 206-metre mark by Wednesday. A flood alert will be issued when it crosses the danger mark of 205.3 metres," he said.
Incessant rains have battered parts of Uttarakhand, Himachal Pradesh and north Uttar Pradesh over the last few days. The catchment of the Yamuna river system covers parts of Uttar Pradesh, Uttarakhand, Himachal Pradesh, Haryana, Rajasthan, Madhya Pradesh and Delhi.
The low-lying areas near the river in Delhi are considered vulnerable to flooding. They are home to around 37,000 people.
The Yamuna had breached the danger mark of 205.33 metres on August 12, following which around 7,000 people were evacuated from the low-lying areas near the river banks.