Zafar Mahmood -  (Episode 13) - One of the perceptions, which plays on the base fears of the general public residing in Peshawar Valley, pertains to drowning of Nowshera and adjoining areas.

The emotive intensity of the debate regarding Kalabagh Dam (KBD) Project is so high that many people living in areas, which would allegedly get adversely affected, tend to believe the assertions of an engineer who worked almost his entire life building roads while working in Highway Department.

The coercive power of fear is so strong that opinion of such a person is believed over those who have far higher credentials to educate us regarding the possible ill-effects of a water storage project on a certain region.

How the fear factor came into play

It so happened that Kalabagh consultants (a group of five companies: Binnie & Partners, Harza Engineering, Preece, Cardew & Rider, Associated Consulting Engineers and NESPAK), were conducting studies to ascertain the water level in case the future floods attained the level of the one experienced in 1929.

This was necessary because in the short period of peak filling the tail of KBD reservoir would intrude into River Kabul near the town of Akora Khattak.

The low-ranking officials, working on KBD Project, were marking the hills surrounding the settlements with a view to ascertain the need to build dykes if the floods attained the historic peak.

The residents of Akora Khattak looked with apprehension at the marking on hillocks by the Project officials. On enquiry, they reportedly got the wrong answer from the officials that water in this area would attain the marked level after KBD was built.

Nobody knows for sure whether the labourers and the low-ranking officials were deliberately displaying their skills at dark humour to the local residents, or they were themselves misinformed.

But their ill-fated remarks created such consternation that people of the area gathered to launch an agitation against the unknown effects of the would be Project, located far away in Punjab.

The freakish incident is well known in engineering circles. A renowned engineer, Bashir A. Malik, describes the factual account bit differently in his book, “Save water, save Pakistan”, in the following words:

“According to the project consultant, what happened was that field survey staff put in marker slabs to indicate ground levels for marking cross-section of the Kabul River. There was an element of resentment against the dam amongst the local people most of whom belonged to ANP. Some of them removed the survey markers and put them on their roof tops to pretend that their houses would be submerged by Kalabagh reservoir. The consultant refuted it saying that it was absolutely wrong and a pure fabrication.”  

The factual position indicates that backwater effect of Kalabagh pondage would end about 10 miles downstream of Nowshera.  A state-of-art computer based study, backed by physical modeling in Pakistan, has established that recurrence of record flood of August 1929 would not affect the water level at Nowshera even after 100 years of sedimentation in the reservoir.

The computer study did not include the effect of Tarbela reservoir which is now actually providing relief by attenuating flood peaks.  These studies were reviewed by a Chinese expert Dr Lianzhen and later by an International Panel of Experts (IPOE), headed by Dr. Kennedy of USA, who most importantly was nominated by Government of NWFP as per their request to Ministry of Water & Power in 1987 which accordingly gave directions to WAPDA for his inclusion in IPOE.

Both reviews are highly supportive of these studies. The IPOE has stated in their report that the results of this study are conservative. With the reservoir drawdown at Elevation 825 feet, the gorge will function very much as it does at present.  Sediments that may have been deposited at constrictions in the gorge will rapidly be scoured away by the water flowing through the gorge.  This scouring section will progress upstream removing any sediments that were deposited above the gorge while the reservoir level was high. High flows during the sluicing period will increasingly carry the amount of silt that had been deposited.

WAPDA chairman, accordingly, in his letter, dated August 20, 1991, addressed to the then chief minister of NWFP, now KP, sought confirmation that the IPOE review report was sent to the Government of NWFP in 1988 and no comments were received.

WAPDA Chairman further informed that “WAPDA studies, as confirmed by Panel, stood undisputed.”

It is most unlikely that detractors of KBD would suddenly start believing in the intellectual integrity of the engineers who prepared the feasibility of KBD. It creates a difficult and challenging situation. However, if KP becomes the employer of the consulting firm to review the feasibility studies, at least the apprehension that WAPDA has been influencing the consultants as an employer would not remain valid.

So if a consensus is to be obtained, such studies may once again be needed in collaboration with the Government of KP.

KBD is neither technically nor economically a feasible project as the reservoir would silt up very quickly. It would have short life as the existing design allows sedimentation to fill it in a short span of time.

The opponents of KBD often quote an excerpt from KBD Report and claim that, "the death of a reservoir begins the day it is built". According to them, KBD main report on page 4.11 in para 4.55 also reveals that heavy silting will take place in the 3.5 MAF Attock portion of the KBD reservoir against the heavy inflow of about 90 MAF of water.

On this basis, they opine that KBD reservoir has the poorest capacity inflow ratio in the world; therefore it will rapidly silt up. They had also claimed earlier that Tarbela is fast losing its silt trap efficiency after performing 30 years of service. It is also asserted that muddy Kabul River would contribute about 110 million tonnes of silt equal to 0.1 MAF (million acre feet) annually in addition to 0.2 MAF of silt flow from Tarbela Reservoir.

The fears and apprehensions about threat of early sedimentation are due to formatting the presentation. The approach was to pick and choose excerpts from various reports and studies. By quoting a line from the consultant’s report, a wrong impression is created. The fact with regard to above quoted fiction is clarified by quoting full Para 4.55 on page 4.11 of Project Planning Report which is reproduced below;

“The rate at which Kalabagh losses storage due to sedimentation will initially be not very high because Tarbela will be trapping most of the sediment from the upper Indus. With sluicing at El. 825 feet (lowest reservoir level for power generation) for fifty days, it will be possible to ensure that the rate of loss of storage in Kalabagh will be much less than the current rate of loss of storage in Tarbela”.

Moreover, in para 6 of his letter Mr. A. P. Fraser, Project Manager of the KBD Project states, “A special feature of the project is that it is designed for mid-level sediment sluicing every year to ensure that its live storage is available for many generations.”

The international experts who designed KBD feel strongly that shape of the Kalabagh reservoir, a long ninety mile narrow gorge along the main stem of the Indus River, provides ideal setting for efficient sediment sluicing compared to a wider valley type reservoir. They claim that its unique geometry provides excellent prospects for sediment transport as well as sluicing through Kalabagh reservoir. The orifice spillway of Kalabagh Dam has its crest elevation 40 feet below the minimum reservoir level of 825 feet (SPD). The operational rules specify the retention of the reservoir at the minimum level of 825 feet (SPD) in the months of June and up to 20th July, which will enable direct sluicing of the silt laden early floods, as well as the removal of the sediment deposited in the preceding months. The long and narrow gorge type reservoir favours flushing of the reservoir by high flows during the flood seasons. These features allow considerably less sedimentation in the reservoir and infact, give a perpetual life to Kalabagh reservoir. These conclusions are based on a very extensive study, using the latest engineering techniques. Experts of international standing have verified and confirmed these conclusions.

The writer can be reached at chairman@wapda.gov.pk