The Yamuna river shot above the danger mark of 205.33 metres in Delhi with the water level rising to 205.38 metres at 4 pm on Friday, 12 August.
The Delhi flood control room, which had earlier predicted that the water level would breach the danger mark on Saturday, 13 August, issued a warning on the night of 11 August, following heavy rain in the upper catchment areas.
Thirty-four boats and mobile pumps were deployed in anticipation of flooding in low-lying areas. The warning advised all sector officers to keep vigil in their respective areas and take necessary action at vulnerable points.
A flood alert is declared in Delhi when the discharge rate from the Yamuna Nagar-located Hathnikund Barrage crosses the 1 lakh cusecs (2831684.69 liters/second) mark, following which people living near the floodplains and in flood-prone areas are evacuated.
Cusec (1 cusec = 28.32 litres per second) is a unit used to measure flow, especially that of water.
In 2019, the flow rate had peaked at 8.28 lakh cusecs on 18-19 August, and the water level of the Yamuna had hit the 206.60-metre mark.
The Delhi government had to launch evacuation and relief operations after the overflowing river submerged many low-lying areas.
(At The Quint, we question everything. Play an active role in shaping our journalism by becoming a member today.)