HYDERABAD: First peak of floodwater is passing through Indus at Guddu barrage for over 24 hours while another peak is expected on Aug 8 when the barrage is likely to receive a flow of 650,000 to 660,000 cusecs of water that indicates high flood.
Some irrigation experts do not rule out a peak of 700,000 or a little over it in view of the changing weather system. The Sindh irrigation authorities are said to have prepared themselves to deal with a flow of super flood of up to 800,000 cusecs.
A peak of 570,000 cusecs is passing since 4pm on Monday and barrage officials now expect that it would record fall within 24 hours only to receive the second peak on Aug 2.
According to irrigation officials’ calculation, this flow of 650,000 to 660,000 cusecs of water would include around 530,000 cusecs of Indus at Taunsa and around 150,000 cusecs at Panjand. Even in the current peak of 570,000 cusecs, there is water of hill torrents of around 111,000 cusecs received in Indus on July 27 as per Sukkur barrage control room’s calculations.
“The 150,000 cusecs of floodwater is actually the quantum of combined flows from Ravi, Sutlej, Jehlum and Chenab as they are roughly having 15,000 to 20,000 cusecs of flow that would be reaching and will eventually drop at Kot Mithan in Indus before heading for Guddu,” said Abdul Aziz Soomro,Sukkur barrage control room in-charge.
The irrigation authorities consider a flow of 700,000 or a little over it as very high flood and lower than 700,000 cusecs as high flood. But the authorities have put in place preparations to deal with 2010 kind of super floods that had wreaked havoc following a breach on Aug 7 at downstream Guddu at Tori bund, displacing millions in Sindh. A major breach in Molchand Surjani bund at Kot Almo, Thatta, occurred on Aug 26-27 midnight and had damaged the canal system, displacing a large population.
“In all fairness we must be ready to deal with a flow of 700,000 cusecs of water in Indus due to changing weather patterns,” said an irrigation expert who has served in the Sindh Irrigation Drainage Authority (Sida).
He specifically mentioned that in 2010 super floods actually more floodwater was received in Indus at Guddu and Sukkur than what was officially claimed.
“The longer river water stays with dykes, the more is the threat to their stability. Their weakness increases if floodwater quantum is increased simultaneously and that’s why we check the bund round the clock,” said a Kotri barrage related officer.
In the 2010 super floods, the authorities had claimed that Guddu had passed 1,148,738 cusecs upstream and 1,148,200 cusecs downstream on Aug 8. Kotri barrage upstream discharge was recorded at 964,897 upstream and 939,442 cusecs downstream before the flood headed for the sea.
According to Mr Aziz, Taunsa has started recording a fall in its discharge. “It is around 388,000 cusecs now and in the morning it was 426,000 cusecs,” he said. That’s why, he said, Guddu would also start recording a fall in the next 24 hours in its first peak.
About the second peak of flood, he said, Flood Forecasting Division (FFD) in its advisory had put the second peak at Taunsa on July 31 at 580,000 cusecs. “There is only a little variation in our and FFD’s assessment, though our dates when the peak is to pass at Taunsa will remain same. At Sukkur we expect the second peak to pass on Aug 6,” he said.
Tarbela Dam — a major reservoir at Indus — is stored by 1,542ft, according to latest figures and it could still store another eight feet of water as its designed capacity is 1,550ft. Storage level at Mangla over River Jehlum is 1,236ft against its maximum storage of 1,242ft. In Sindh, the canal withdrawals are either zero or have been reduced drastically. Sukkur barrage’s canals are drawing 10,000 cusecs of water while 2,000 cusecs at Guddu’s three canals. Kotri barrage withdrawal for its four canals is zero.
Last year when floodwater caused widespread destruction in Punjab, the river flows in Indus had become a guessing game for the Sindh irrigation authorities. At one stage, a flow of one million cusecs was expected and then estimates had to be revised at 400,000 cusecs or 500,000 cusecs when new figures of discharges were shared with the Sindh authorities by their Punjab counterparts.
Published in Dawn, July 29th, 2015