After wreaking havoc on lives and livelihoods in parts of Delhi close to it, the swollen Yamuna on Saturday morning followed a downward trend, albeit at a slow pace of a few centimetres per hour.
However, it is still flowing over two metres above the danger mark of 205.33 metres.
The situation could worsen if weather predictions of more rain in the capital and upper catchment areas come true.
According to the Central Water Commission's flood-monitoring portal, the Yamuna water level declined to 207.62 metres by 7 am on Saturday from its peak of 208.66 metres at 8 pm on Thursday.
With the flow rate from the Hathnikund Barrage in Haryana's Yamunanagar decreasing over the past two days, further decline is expected.
The India meteorological department, however, anticipated moderate rain in the city over the next two days and "heavy to very heavy" rainfall over Uttarakhand, Himachal Pradesh, and Uttar Pradesh during the next five days, raising concern about a rise in the water level in the river.
In the case of more rain in Delhi, experts said, stormwater may overflow and take longer than usual to drain out. Waterlogging could compound the situation further.
Friday marked a turning point as the raging Yamuna and the resulting backflow of foul-smelling water from drains spilled into prominent locations such as the Supreme Court, Raj Ghat, and the bustling intersection at ITO.
Prior to the misery on Friday, the river water had already reached the rear ramparts of the Red Fort and inundated one of the city's major bus terminals at Kashmere Gate.
The Ring Road, constructed partially over floodplains, remained closed for the third consecutive day near Kashmere Gate.
The city has been grappling with waterlogging and flooding issues for a week now.
Initially, a downpour caused intense waterlogging on July 8 and 9, with the city receiving 125 per cent of its monthly rainfall quota in just two days.
Subsequently, heavy rains in the upper catchment areas, including Himachal Pradesh, Uttarakhand, and Haryana, led to the Yamuna swelling to record levels.
The river reached 208.66 metres on Thursday, surpassing the previous all-time record of 207.49 metres set in September 1978 by a significant margin.
The river breached embankments and penetrated deeper into the city than it has in over four decades.
With the situation deteriorating every passing hour from Sunday to Thursday evening, Delhi Chief Minister Arvind Kejriwal urged the Centre to intervene and the Delhi Police imposed Section 144 of the CrPC in flood-prone areas to prevent public movement there.
The army was called in for the first time since the 2010 floods to repair a broken flow regulator at drain no. 12, the reason behind the flooding in central parts of the capital on Friday.
The consequences of the floods have been devastating with around 23,000 people evacuated from their homes. The losses incurred in terms of property, businesses, and earnings have amounted to crores.
Experts attribute the unprecedented flooding in Delhi to encroachment on floodplains, extreme rainfall occurring within shorter durations, and silt accumulation that raised the riverbed.
A senior official at the Central Water Commission (CWC) told PTI that the water released from the Hathnikund Barrage took less time to reach Delhi this time as compared to previous years.
"The main reason could be encroachment and siltation. Earlier, the water would have more space to flow. Now, it passes through a constricted cross-section," he said.
According to Yashveer Bhatnagar, country representative of the International Union for Conservation of Nature, the record water level in the Yamuna can be attributed to intense rainfall in the entire upper catchment area.
"Encroachment of the floodplains may have an incremental effect," he said.
Bhim Singh Rawat, associate coordinator, South Asia Network on Dams, Rivers, People, said the unprecedented rise in the Yamuna water level is due to riverbed elevation because of significant silt accumulation.
"More than 25 bridges within the 22-km river stretch from Wazirabad to Okhla obstruct the flow, leading to deposition of silt in the riverbed and formation of a lot of mid-stream sandbars," he told PTI.
The Yamuna river system's catchment covers parts of Uttar Pradesh, Uttarakhand, Himachal Pradesh, Haryana, Rajasthan, Madhya Pradesh, and Delhi.
The low-lying areas near the river in the northeast, east, central, and southeast districts, inhabited by around 41,000 people, are considered prone to flooding.
A study on "Urban Flooding and its Management" by the Irrigation and Flood Control Department identifies east Delhi under the floodplain region and highly vulnerable to floods.
Despite this, encroachment and development have occurred at a rapid pace in the ecologically sensitive region over the years.
Letters exchanged between the Delhi Forest Department and the primary land-owning agency in the city, Delhi Development Authority, show that 2,480 hectares of land in the Yamuna floodplains have been encroached upon or developed since 2009.
