HYDERABAD, Nov 20: A study is being carried out on Sukkur barrage to look into ways of protecting and strengthening the 80-year-old structure, lifeline of the province's agricultural sector, and enable it to withstand increasingly dangerous levels of flood in the river.

Part of a larger study of three barrages of Sindh, the exercise is being conducted jointly by Atkins, National Development Consultants (NDC) and Associated Consulting Engineers under the Water Sector Improvement Project (WISP) phase-I of the Sindh Irrigation and Drainage Authority (SIDA).

Sukkur Barrage withstood a flow of over 1.1 million cusecs of water against its capacity of 900,000 cusec during last year's flood.

Water experts believe the barrage's structure needs to be strengthened in view of increased flood levels recorded last year. They propose to reopen its 10 gates closed in 1945 after the barrage started operation in 1932 to cope with increased flows.

“I think we should look into a new theory called Khosla's theory as the barrage was built in line with Bligh's theory and its structure has withstood the test of times,” according to former chief engineer of irrigation department Noor Mohammad Baloch.

He said the capacity of Guddu barrage required to be increased because it had successfully withstood 1.2 million cusecs of water last year.

“We need to do it because we anticipate that with changing weather patterns, you can't rule out a flow of 1.4 million cusec reaching Guddu barrage. What will we do then? Therefore, we must make preparations now,” Mr Baloch said.

Former secretary of irrigation Idrees Rajput said 10 gates of Sukkur barrage had to be closed and a bifurcated point was created upstream to reduce flows of water with strong silt content. “It had to be done because right bank canals were having heavy silt content,” he said.

He said an island was created upstream with a submerged regulator. “It is used to bifurcate flow of waters with lesser silt towards the right bank canals and the remaining flow towards main current. A tail channel which was needed to operate this system efficiently was also created,” he said.

But now, he said, there was insufficient flow of water and silt deposits. Therefore, the consultants would also examine this issue, said Mr Rajput, who is associated with the NDC.

At the bifurcation point, he said, the levels of tail channel and riverbed were different which ensured diversion of one third of water to the right bank canals with lesser silt deposit and the remaining to tail channel.

According to Mr Baloch, the island was created at the barrage's upstream and it was decided that 1.5 times higher water flows than allocation of the right bank canals would be sent to tail channel so that the canals did not receive silt deposits.

“But ever since we gave away our three rivers to India in 1960 the water shortage problem has become perennial, and required quantum of water remains unavailable,” he said.

He said the tidal channel had not been operating since 1999 because of water shortage and the right bank canals were receiving silt deposits.

“The tail channel ensures sending water with lesser amount of silt to the right and the remaining to the downstream. Because of lack of water for tail channel the right bank canals are having silt deposits,” he said.

Mr Baloch lays emphasis on increasing capacity of Sukkur barrage. “Sukkur barrage has passed 1.2 million cusecs twice so far in 1976 and last year,” he said.

He said that tail channel had to be operated under certain rules that directly involved availability of water.

Piers No's 1, 2 and 3 of Sukkur barrage had suffered damage and during annual closure officials discovered large scour pit before the gates' right pocket, which had caused collapse of stone apron, sheet piles and concrete floor.

As an interim measure, the pit was filled with stone and cavities were filled with pressure concrete. Actual work of rehabilitation was started in November 2004 and completed in May 2005.

The study would also include an environmental management plan to discuss issues relating to water shortage and its impact on flora and fauna and measures to mitigate them. It would also see how to address seepage problem.

WISP official Zahid Junejo said the consultants' team was conducting baseline study. They will collect data of last 100 years historical record. About the problem of silt deposits on the right bank canals, he said the consultants would see how to revive the use of tail channel and island.