Higher monsoon inflows at Hathnikund fail to boost Yamuna's flow; experts warn of ecological impact

New Delhi, Even as monsoon rains increased water inflows at the Hathnikund Barrage (HKB) on the Yamuna over the past fortnight, the amount of water released into the river remained largely unchanged for several days, raising concerns among experts over the ecological health of the river downstream in Delhi.

According to a report by the South Asia Network on Dams, Rivers and People (SANDRP), an analysis of the Central Water Commission's (CWC) data on hourly discharge from the Hathnikund Barrage showed that inflows into the barrage increased steadily after the onset of the monsoon.

However, most of the additional water continued to be diverted into the western and eastern Yamuna canals, with only lean-season quantities reaching the river for much of the period.


The report said that from July 1 to July 5, average daily inflows at the barrage rose from about 192 cumecs to nearly 242 cumecs, but releases into the river remained constant at 9.97 cumecs, or roughly 352 cusecs, throughout the day, with almost the entire remaining flow diverted into canals.

The trend continued through much of the following week.

Even on July 8 and July 9, when average inflows rose further to around 390 cumecs and 442 cumecs, respectively, river releases remained close to the lean-season level for most hours, increasing only briefly during periods of exceptionally high inflows.

By July 14, releases had largely returned to around 9.97 cumecs despite inflows remaining substantially higher than at the start of the month, according to the report.

For Delhi, where the Yamuna receives untreated sewage, industrial effluents and urban runoff along its 22-kilometre stretch, environmentalists say the absence of higher monsoon flows deprives the river of its natural ability to dilute pollutants, transport sediments and recharge floodplains.

Bhim Singh Rawat, a Yamuna activist and member of SANDRP, said the river is naturally capable of cleaning itself during the monsoon if adequate flows are allowed to pass downstream.

"The river is naturally equipped to clean itself out during the monsoon, when flow is higher. But if the excess water is constantly being diverted into canals or used up for our purposes, while keeping the flow of the river the same as the lean season or summer season, then that inevitably contributes to the Yamuna pollution in the long term," Rawat told PTI.

He said the current practice of releasing 352 cusecs or 9.97 cumecs into the river was decided for the lean season and should not continue during the monsoon.

"Ideally, the river should receive at least 75 per cent of its natural inflows to sustain its ecological and hydrological functions," he said, adding, "Under a worst-case scenario, no less than 50 per cent of the available inflows from the Hathnikund Barrage should be released into the river, particularly during the monsoon, when rainfall reduces irrigation demand in the canal system," he said.

The SANDRP report also flagged concerns over environmental flows during the lean season. It said more than six years have passed since the National Institute of Hydrology (NIH) recommended a minimum environmental flow of "812 cusecs" for the Yamuna, but the "Ministry of Jal Shakti has not notified these environmental flow requirements, leaving the recommendation without any legal or operational effect".

Environmentalists have long maintained that while sewage treatment plants, interception of drains and pollution-control measures are essential for cleaning the Yamuna, they cannot by themselves restore the river without ensuring adequate environmental flows.

Rawat questioned why maintaining the river's natural flow has not featured more prominently in official efforts to rejuvenate the Yamuna.

"There has been constant talk about cleaning the Yamuna, but preserving the existing river itself has not been on the priority list. Without ensuring adequate flow, it is difficult to expect lasting improvements," he said.

The issue comes as successive governments continue to invest in sewage treatment infrastructure and pollution-abatement projects for the Yamuna, even as river experts argue that restoring environmental flows upstream is equally critical for the river's long-term revival.