Rampant unchecked construction on the floodplains of the Yamuna river poses a grave threat not only to the survival of the river but also to the city, say experts.
Such construction has significantly reduced the flood-carrying capacity of the river as it flows through the capital, and a major flood in future could cause serious damage, they add.
Data show that the city has experienced major floods at least once every decade since 1947. The 1978 floods, with the water level reaching 207.4 metres at the Old Railway Bridge, had inundated areas as far as Model Town and Mukherjee Nagar in north Delhi.
According to Yamuna Jiye Abhiyaan Convener Manoj Misra, the floodplain that one finds in Delhi today — squeezed between the Ring Road in the west and the Noida Link Road in the east — is a minuscule portion of what it used to be.
A floodplain is the area near a river which is not always under water but floods when the water rises. In Delhi, the Yamuna’s floodplain is defined as that area near the river that gets submerged at least once in 25 years.
The capital’s floodplains have “been further compromised through construction of ‘pseudo bridges’ (beginning with the Hazrat Nizamuddin railway bridge), metro depots and stations, bus depots, Ring Road bye pass road, Akshardham and later the Commonwealth Games Village”, Misra said.
Misra defines a pseudo bridge as one built only over the “lean season flow” of a river, with rest of the floodplain cross-embanked through a raised approach road, and not on stilts as it should be to enable free and easy flow downstream of flood waters.
He adds that encroachment — both open and insidious — continues to take place, especially in the south near Jaitpur village on the Delhi-Haryana border, and in the northeast at the Delhi-Uttar Pradesh border.
“Almost 30 per cent of the floodplain in the city has already been compromised and is no longer available to the river,” he says, adding that the reduction of floodplain will have a two-fold impact.
“One is through direct damage to life and property that might result from flood waters entering inhabited areas in case of excessive rains. Secondly, even if somehow physical loss is prevented, the flood waters, which otherwise spreads over the floodplains and recharges the ground water, would not be able to do so,” says Misra.
“It would run away downstream, finding little floodplain within the city to spread, stand and become ground water.”
Environment activist Anand Arya, one of the litigants in a case before the National Green Tribunal (NGT) against the recent Art of Living event held on the Yamuna floodplains, says that ignoring the long-term impact of activities on the floodplains will be hazardous.
“Today nothing will happen. But when there is rainfall that happens once in 50 years or once in 100 years, that once-in-fifty-year flood will, in all probability, drown the whole of east Delhi, Noida and even Greater Noida,” says Arya.
According to him, it was very fortunate that the Congress party had its governments in Delhi, at the Centre and in Haryana in 2010, the year the Commonwealth Games were held.
“The kind of rainfall that happened that year, it would have flooded the city. They bridged the river at Karnal and Kurukshetra. They flooded the rural areas of Haryana so that Delhi remained safe,” Arya says.
“If all the water had reached Delhi, it would have drowned about three floors of the Commonwealth Games Village and completely submerged Akshardham, apart from many other areas of east Delhi,” he contends.
Ravi Monga of the Yamuna Muktikaran Abhiyaan says that as the size of Indian rivers expands several times during the monsoon, the reduced flood-carrying capacity could lead to severe damage.
“In European countries, the rivers get consistent flow of water throughout the year. But in India, we have monsoon. So we receive most of the water on our land in just one to one-and-a-half months of the year,” Monga points out.
“This is the period when all the rivers of the country overflow and the size of the river expands to over eight-nine times its original size.”
According to a report, “Restoration and Conservation of River Yamuna”, the embankments and numerous constructions on the floodplain have already constricted the river zone to a very narrow space. At many points, the channel flows along the embankment and, hence, has no floodplain left, the report notes.