Flood management at Hirakud dam in question: Was Mahanadi flood avoidable?

Heavy rains in Chhattisgarh and Odisha made the Mahanadi river swell forcing Chhattisgarh to throw open its barrages and the Hirakud dam to open its gates as well. The floods currently being witnessed by 10 districts in Odisha are said to be the largest and most devastating in the last 11 years.

However, as the data and expert opinions continue to flow, the question and concern is getting shriller; was the flood completely unavoidable and nothing could have been done to protect the property of the common man?

To answer this question, we need to see the swelling of Mahanadi and the subsequent flood in an entirely different perspective. From politicians to common man, everybody in Odisha has been blaming the Chhattisgarh for constructing a number of barrages over Mahanadi leaving the state of Odisha dry in the summer. But when the rains came pouring down over Chhattisgarh, the state government opened the gates of its barrages filling the reservoir at Hirakud brimming with water. This is where the experts express their concern.

Some people also expressed their concern on the water-bearing capacity of the Hirakud reservoir. It is 64 years old and has to hold on to a water level of 627 feet. Though the reservoir is designed to hold water up to a level of 630 feet, as an ageing reservoir, holding so much water for a very long time can make difficult situations for the authorities. The situation now warrants the installation of a gauge station at the upper catchment area of Mahanadi to ascertain the flow of water and calculate the gate opening exercise subsequently.

Asked about the capacity of the Hirakud reservoir, the Engineer in Chief of the Water Resource Department, Bijay Mishra said, “We can use the full capacity of the Hirakud reservoir for flood management. We have even stored flood water up to 630 feet in the past.”

Even the desilting exercise would have helped the reservoir a lot. Speaking to OTV, Chief Engineer of the Water Resource Department, Jashobanta Parida said, “The reservoir also accumulating silt on both its sides. When a lot of water is stored at a particular space, it becomes vital to desilt the reservoir in regular intervals.” However, the EIC, Bijay Mishra refuted the statement and said, “We are already studying the silt deposit on the reservoir bed and we will take an appropriate decision soon. But the silting does not affect the reservoir at all.”

As per the Unit Head of Hirakud Dam, Anand Chandra Sahu, the ‘Rule Curve’ of the dam helps calculate how much water the reservoir can keep in a particular time of the year. However, given the geographical condition and change in rain pattern, it was suggested to review and change the rule curve every 10 years. But Hirakud dam witnessed an exception in here. The rule curve was never reviewed after 1988.

“We have already requested the State government to review the rule curve and I am hopeful that steps in this direction will be taken soon,” said Sahu.

Not only the rule curve, but the Odisha government has also miserably failed to construct barrages at the downstream of Mahanadi in the last 20 years which would have helped regulate the flood water in time of needs.

It is pertinent to mention here that the Odisha government had announced to construct seven barrages in the recent past, but not a single unit has been able to get operational till now.

Notably, Odisha has seen big floods in 1982, 2001, 2006, 2008, 2011 and 2020. But despite a comparatively low volume of water flowing in the Mahanadi system this time, the flood situation in the downstream areas has worsened.