The water level in the Yamuna here neared the warning mark of 204.5 metres on Sunday following heavy rain in the upper catchment areas and is expected to breach it on September 26, officials said.
The Delhi flood control room said the water level reached 204.4 metres at 9 pm. It is likely to rise to 204.7 metres between 10 am and 12 noon on Monday.
A flood alert is sounded in Delhi when the discharge rate from the Hathnikund barrage in Haryana's Yamuna Nagar crosses the 1 lakh-cusecs mark. People living near the floodplains and in flood-prone areas are evacuated then.
The Delhi flood control room reported a discharge rate of around 45,352 cusecs at 8 pm.
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.
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.
(Inputs from PTI)