HYDERABAD: Sindh irrigation authorities and experts are guessing the actual amount of floodwater to hit the Guddu barrage as they believe their Punjab counterparts are feeding them exaggerated or incorrect data on floodwater flows.

The Sindh authorities, however, feel a little complacent now after making calculations and arriving at their own conclusions about the floodwater.

At one stage it was anticipated that Sindh was likely to receive one million cusec of floodwater like it did in 2010. But the latest updates have put the irrigation authorities at ease and they feel on the basis of Monday’s discharge at Panjnad the flows could be between 400,000 and 500,000 cusec.

Variations between flows in the Chenab and Jhelum, said senior officials, remained quite unusual. For example, from 947,099 cusec from Chenab wing a week back at Khanki and 903,504 cusec at Qadirabad the same day with 11 hours time lag, flows suddenly dropped to 306,322 cusec with exceptional water losses of 597,182 cusec at 11am on Sept 9 at Trimmu, the area where the Jhelum and the Chenab meet, they said.

Likewise, they said, 516,387 cusec of Jhelum wing (out of it 499,600 cusec was actually released from Mangla dam) was recorded at Rasul on Sept 6. After deduction of travelling losses out of 516,387 cusec, 163,024 discharge was recorded at 8am Trimmu on Sept 8 which according to a barrage official was surprising because no breach had been made in the Jhelum area at that time.

“We fail to understand the figures which remain confusing,” he said.

He informed that 306,322 cusec must have flows of 163,024 so if this quantum was deducted from 306,322 cusec the losses or disbursement of water between Qadirabad (903,504 cusec on Sept 7) and Trimmu (306,322 cusec on Sept 9) would be still more.

“It is around 1,400,000 cusec of both Jehlum and Chenab wings if they are synchronised at Trimmu upstream. Peak of 626,000 cusec flowed down Trimmu on Sept 10 at 7pm. It indicates that around 55 per cent of flows (774,000 cusec) have been lost due to breaches which is not understandable as according to Flood Forecasting Division’s claim around 25,000 cusec were passing through Athara Hazari town at that time and then breach flows increased to 130,000 cusec,” remarked an official.

He maintained that disbursement of water after more breaches after Athara Hazari was understandable but not to that extent which was being projected. The first breach was given at Trimmu upstream when it was having a flow of 600,000 cusec at Athara Hazari town according to FFD’s report although the barrage had designed discharge capacity of 645,000 cusec, he said.

Floodwater maintained a steady flow of 370,000 cusec at Panjnad on Sunday at 5pm and it remained 351,000 cusec between Sept 13 and 14. Then on Monday it showed up and downstream discharge of 379,562 cusec at 6am. After 12 hours the discharge increased to 413,569 cusec in the evening, he said.

Although it was still rising but officials believed that it was not the flow from main current and was regenerated water that entered the system again after diversion from breaches upstream.

“We had expected a flow of 800,000 to 900,000 cusec initially given pre-breaches flows of Chenab and Jhelum which accounted for around 1,400,000 cusec including Ravi’s discharge.

“Considering post-breach flows we revised them to between 700,000-800,000 cusec. We expected 600,000 to 650,000 cusec even after breaches and having flows of Ravi and Indus rivers. But data now indicates that Guddu might be receiving 500,000 to 600,000 cusec,” said Sindh secretary irrigation Babar Effendi on Monday.

He said: “We are told by our counterparts that Panjnad is still rising and that it hasn’t passed its peak though it rising very slowly to a few thousand cusec.”

Former secretary of irrigation Idris Rajput said that correct and actual measurement had remained an issue and believed if present post-breaches figures were to be relied on then Guddu barrage would be receiving around 400,000 cusec.

“Usually discharges are calculated while using gauge discharge curve otherwise actual flows are to be measured inside the river which we used to do perhaps until 1976 by going inside the river on a motorboat,” he said.

According to him, flows that are passing through Panjnad are more reliable than discharges of Khanki and Qadirabad which are always high unusually.

The latest figures make irrigation officials feel confident that river flows will flow easily down to the sea without posing any threat to the river dykes.

The peak of floodwater is expected to hit Guddu tonight (Sept 15-16 midnight).

Guddu barrage had received 567,418 cusec discharge upstream and passed 542,100 cusec downstream last year on Aug 21.

During super floods of 2010, it had withstood a flow of 1,148,200 cusec downstream on Aug 8.

Published in Dawn, September 16th, 2014