Bhubaneswar, Sept. 24: Excessive silting is a major factor behind recurring floods in the state but there are no easy solutions to this problem, say experts.

Rapid siltation has been taking place in Hirakud reservoir on the Mahanadi, the focus of the current floods in the state.

Former Hirakud chief engineer Sudhakar Patri said nearly 25 per cent of the live storage capacity of the reservoir, which is 3.91 million acre feet, has been lost to siltation in the 54 years of its existence. Sedimentation is endemic not only to the Mahanadi and its tributaries, but also most other rivers in the state.

As their beds rise following a sustained piling of sand, the rivers lose their carrying capacity and becoming increasingly flood-prone.

“Dredging of silted river mouths and raising the height of embankments could be a solution but it is easier said than done. As far as the Hirakud dam is concerned, there has been no such proposal to the best of my knowledge. And even if your dredge, what are going to do with the excavated material?” asked Patri. Project coordinator, Odisha State Centre, Forum For Policy Dialogue on Water Conflicts in India, Pranab Ranjan Choudhary agreed that the discharge capacity of rivers into the sea was falling because of heavy siltation.

He said that the Hirakud dam’s retention capacity was only around five per cent of the water it received every year.

An idea of the kind of silt load the Mahanadi and its branches carry can also be had from the amount of silt some of them discharge into the Chilika lagoon. On a rough estimate, four tributaries of the Mahanadi including Daya and Bhargavi empty 1.8 million tonnes of sediment into the lagoon. Their beds have risen significantly over the years and now they overflow more frequently than in the past.

Rapid sedimentation has also been taking place in several other major rivers of the state such as, the Brahmani, which feeds a large number of industries besides meeting the drinking water needs of a large population. Brahmani’s catchment area is reportedly heavily silted at Jenapur and Bedipur making the river just as flood-prone as the Mahanadi.

The government’s stock response to the challenge of floods has been construction of protective embankments which now run to a length of 7137.75km across the state. However, embankments alone cannot protect the state from floods.