How Hirakud dam is hugely vulneable and can be a big threat...

Hirakud Dam

let's spare some thoughts for Hirakud. We have to. We just can't escape without thinking about it. The dam itself is highly vulnerable to flood flow, and in being so, it makes a large part of Odisha hugely vulnerable to a major disaster. 

The current live storage capacity of Hirakud reservoir is 3.6 Million Acre Feet or even less. After recent rainfall in Kalahandi and Balangir, the Tel River continued to flow over 9 lakh cusec for over 12 hours (as measured at Patharla river gauge station). Suppose this volume of water enters Hirakud reservoir and let’s further suppose that Hirakud reservoir is totally empty, at its dead storage level of 590 ft as flood flow of that volume starts entering the reservoir. Do you know how long it will take to reach the reservoir’s Full Reservoir Level (FRL) of 630 ft? With an inflow of about 9 lakh cusec, Hirakud will take a mere 48 hours to get totally filled up from dead level.

Just imagine the threat: Hirakud reservoir’s catchment is 3.6 times larger than Tel river’s basin area. This means, if rainfall of similar intensity, as was in Balangir and Kalahandi occurs in Hirakud’s command area, occurs in Hirakud’s catchment area; it will take just about 12 hours for the reservoir to get full from its dead storage level. The dam does not stay at dead storage level – especially from August onwards.

Let’s further remember that vast area of Western Odisha – including Sambalpur, Burla and Hirakud - had received >500 mm rainfall in a single day last year.

Hirakud reservoir is absolutely incapable to handle such inflow. Its current water Release Capacity - through the entire existing 34 nos. of spillway gates & 64 nos of under sluice gates of Hirakud Dam - is a mere 42450 m3 /sec or about 15 lakh Cusec. Some of gates have never been opened and probably are not in a position to open. In the meanwhile, the Central Water Commission (CWC) has enhanced Probable Maximum Flood (PMF) to 69632 m3 /sec or about 24.6 lakh Cusec. Just imagine the threat.