Odisha Sun Times Bureau
Sambalpur, Aug 6:
With the threat of high flood in the Mahanadi river system in Odisha looming large, questions are now being raised over the management of floodwater by the Hirakud dam authorities and the opinion that the situation could have been averted had the rule curve properly followed, is gradually gaining credence.
The Mahanadi bed lies 500 feet above the sea level while the reservoir has a maximum water holding capacity of 630 feet.
As per the rule curve, water level of the reservoir should be at the optimum level of 630 feet by September 30 and 615 feet by August 11.
Going by the standard specification, the dam authorities have grossly violated the rule curve this year.
It is worthwhile here to mention that out of the total catchment areas of Mahanadi, about 90 percent are in Chhattisgarh and the rest 10 percent in Odisha.
The dam authorities had released the first instalment of floodwater through 20 gates on July 24 due to heavy rains following a low pressure.
With the water level of the reservoir at 620.27 feet, the authorities on the next day opened three more gates.
As the water level had come down to 619.23 feet and 618.23 feet on July 26 and 27 respectively, the dam authorities closed down 13 gates while continuing to release the floodwater through 10 gates.
On July 28, the authorities had closed 6 gates by regulating the water at 617.54 feet.
The water level of the dam had remained at 617.54 feet, 618.47 feet and 620.58 feet on July, 29, 30, 31 respectively while the floodwater was getting released through four gates.
The dam authorities could have released more water after that. But instead of doing this, they had waited till the water level reached 623.95 feet on August 1, a situation that forced them to open 20 more gates.
Surprisingly, the dam authorities closed all 24 gates on August 2 when the water level of the reservoir was 622.60 feet.
Keeping the flood situation in the lower catchments of the river, the dam authorities on August 3 had opened five gates with the water level at 621.58 feet.
However, they had opened 17 gates on August 4 as the water level went up to 622.85 feet due to heavy rains in the upper catchments.
Keeping the flood situation in Sambalpur district in mind, the authorities had closed two gates in the morning of August 5, but again opened nine gates in the evening.
Considering the massive inflow of floodwater into the reservoir, it is more likely that the dam authorities, who have already opened 40 gates this morning and are likley to open 10 more later in the day, would be forced to open even more gates if rain persists in the upper catchments.
When contacted, the superintending engineer, Hirakud dam, Rabindra Kumar Panda said it is not always possible to adhere to the rule curve. The dam authorities had closed the gates in view of the flood situation in the lower catchments.
“Had we not closed the gates at that time, the situation could have been more precarious”, he pointed out.