Yamuna's peak at lowest in 10 yrs, so river didn't get its annual 'flush'

This year, the water level of the Yamuna failed to cross the warning level of 204.5 metres at Old Railway Bridge, a first since 2014 and only one of six instances recorded since 1963.

- Paras Singh and Jasjeev Gandhiok

This means the river did not go through a single flooding cycle, missing out on the annual flush in the highly polluted stretch between Wazirabad and Okhla, and lack of aquifer recharge, experts say. High pollution load, untreated effluents from industries and domestic sewage are now playing out with meteorological factors as scenes of iceberg-like foam blocks floating on the river surface.

For a river such as the Yamuna, the four-month monsoon cycle when low-level flooding occurs is critical for annual cleaning, when the river flows from mouth to tail in one flow. It helps to maintain a continuous flow, improves aquatic life during this period and also helps recharge the underground aquifers on the floodplains.

To be sure, this flooding does not stop froth formation, but ensures improved river health. Experts said that even though Delhi received 63% additional rainfall this year, the Yamuna level did not cross the danger mark, as besides local rain, there are multiple factors at play that affect the water level of the Yamuna.

Key among this is rainfall in the upper catchment areas of the river and its tributaries, controlled discharge from the Hathnikund barrage, as well as a series of precautionary measures, such as opening of all barrage gates to prevent recurrence of flooding, a senior Irrigation and flood control (I&FC) department official said.