Silt buildup prompts Delhi to rethink Yamuna’s flood danger marks

Delhi proposes raising Yamuna's flood warning and danger marks due to siltation, aiming for better flood forecasting and resident safety.

Due to heavy siltation at the base of the Yamuna, the irrigation and flood control department has proposed raising the river’s warning and danger marks to provide a more realistic marker for warning and evacuating residents in low-lying areas, officials said, News.Az reports, citing Hindustantimes.

According to officials, the Delhi government is considering raising the Yamuna’s flood “warning” mark from 204.5 metres to 205 metres, and the “danger” mark from 205.33 metres to 205.75 metres. Officials said that the river’s base levels have changed due to siltation and a lack of dredging over the years.

The danger and warning levels are important parameters used to forecast floods. These levels depend on the threat perception in the area, and are decided in consultation with the state government. Delhi measures these base levels at the Old Delhi Railway Bridge.

The office of the I&FC minister did not comment on the development.

The water released toward Delhi from the Yamuna, Tons and Giri rivers is regulated at the Hathnikund barrage, located 228km upstream of Delhi. The Yamuna’s highest water level, recorded at 208.66m on July 13, 2023, flooded low-lying areas and breached the previous high of 207.49m set on September 6, 1978. The water flow from the Hathnikund barrage was above 2,00,000 cusecs during the 2023 flooding episode.Data from the irrigation and flood control department over the past 63 years show that the Yamuna has crossed the 207-metre mark only four times.

A senior official said the danger level was last revised in 2019 and needs reassessment following flooding episodes in the past five years. “These levels are now being attained even at low discharge levels from the upstream barrage because the carrying capacity of the river sections has decreased due to base siltation. Attaining this level frequently causes panic,” the official said.

Bhim Singh Rawat, a Yamuna activist and member of the South Asia Network on Dams, Rivers and People (SANDRP) said that the last floods in 2023 exposed three key failures—poor flood forecasting by the Central Water Commission, siltation of the river bed, and encroachments on the floodplain, which led to a situation where even a lesser quantum of water caused a steep rise in water levels. “How can they fail to predict the rise in levels despite having so many monitoring stations? Delhi has one of the oldest flood monitoring stations in the country. There is no transparent mechanism of coordination between the three barrages within the 22km stretch in Delhi,” he said.

Rawat added that the river does not have enough space for water to pass through easily during flooding due to encroachment and siltation. “Just changing the marks is not the solution. We need a proper cross-sectional study, the dumping of construction soil and waste should be stopped and encroachments should be removed.”

According to the government flood protocol, upon attaining the warning level at 204.5m, gates at inlets of some drains are closed, and after attaining the danger level (205.33m), water from the active river course starts spreading into the area within the embankments. “There are some villages like Garhi Mandu, Usmanpur, Madanpur Khadar and other unauthorised colonies that also exist within river embankments. They are most vulnerable and evacuations are mainly carried out from these areas,” an official explained.Earlier, the warning and danger levels at Old Railway Bridge were 204m and 204.83m, respectively. However, in 2019, the warning and danger levels were raised to 204.50m and 205.33m, respectively. “We have proposed that these two marker levels be revised again, but the final decision lies with the government,” the official said.

News.Az 

By Leyla Şirinova