Sambalpur, Nov. 2: The Hyderabad-based National Remote Sensing Centre, which is conducting a survey to estimate siltation deposits in the Hirakud dam reservoir, will submit its report shortly.

Hirakud Dam Project's chief engineer Harmohan Pradhan said: "The remote sensing centre had submitted its interim report, and we have pointed out some mistakes in the report. They will submit the final report shortly."

The Hirakud dam authorities had approached the Hyderabad agency to conduct a survey to estimate siltation deposits in the reservoir in July.

The remote sensing centre's scientists had evinced interest in conducting the survey and collected data on the highest water level and lowest water level of the reservoir.

Subsequently, the remote sensing centre started conducting the survey to estimate the siltation deposit in the reservoir.

"Siltation is a natural process. A survey to estimate the siltation deposits in the reservoir had been conducted in 2005," said Pradhan.

The siltation deposit in the reservoir will be estimated from satellite pictures. The study will also estimate reduction in the water retention capacity of the reservoir.

"It was found that the gross water retention capacity of the reservoir had decreased by 17 per cent when the study on the siltation deposit of the reservoir was conducted in 2005," Pradhan said.

The Hirakud dam authorities had conducted underwater scanning to ascertain the present condition of cracks in the dam. The Central Soil and Material Research Station, New Delhi, was entrusted with the responsibility to ascertain the condition of the cracks.

The team recorded the underwater visuals of the upstream face of the dam with the help of a remote operated vehicle.

The multipurpose dam, formally inaugurated in 1957, has irrigation, flood control, power generation and water transport, besides fishing facilities. The water storage capacity of the reservoir is 4.780 million acre feet. There are 98 gates to release floodwaters from the dam.

Of the total, 64 are sluice gates and 34 are crest gates. Ninety per cent of the catchment areas of the reservoir fall in Chhattisgarh.