The funny claim of Wapda that Kalabagh Dam is one of the most extensively studied projects in the world is totally refuted by more than 26 excerpts in the dam's own feasibility report prepared by the project consultants.
On the contrary, the dam is the most canvassed and publicized project in the world for which a forced consensus is being sought politically in spite of its technical infeasibility. Moreover, Wapda falsely claims that its design is well-documented and be accepted by its critics.
The most amusing design aspect of Kalabagh is that its "restricted mid-level sluicing" design concept dictated by Wapda in terms of reference (TOR) is formally declared as unwanted by the consultants. They have recommended to adopt unrestricted "low level sluicing design."
The consultants have given their honest opinion by disagreeing with its client (Wapda) stating that there is no specific method to sluice silt except "the lower the draw down level, the longer this level is maintained and the higher the flows then the more effective the sluicing will be". For proof, reference may be made to the dam KBD) main project report June 1988, page 3.8 para 3.27. The excerpt from the feasibility report is given below.
"In principle there is no specific mode of operation that must be adhered to each year in order to sluice sediment from Kalabagh but the lower the draw-down level, the longer this level is maintained and the higher the flows then the more effective the sluicing will be."
The above excerpt if technically decoded clearly suggests a barrage type structure with unrestricted low-level sluices rather than a dam with mid-level sluicing structure. Attention is again invited to another very important excerpt from the KBD Project Report 1988 page 3.5, para 3.17. It states: -
"The high sediment load carried by the Indus at Kalabagh has an important bearing on the design of Kalabagh and on the operation rules for the Reservoir. If a high proportion of sediment is trapped the storage volume will rapidly reduce with the loss of irrigation benefits derived from storage. Such sedimentation could eventually also cause unacceptable back-water effects"
This excerpt clearly means that heavy silt load carried by the Indus at Kalabagh plays vital role in selecting the type of hydraulic design for the KBD so as to avoid rapid silting, loss of storage and backwater flooding beside loss of irrigation benefits. The above excerpt therefore confirms to adopt low-level unrestricted sluicing design to cater for the evacuation of heavy and rapid silting in the Kalabagh Reservoir as the hydraulic design has an important bearing on the project and on its life span and service value. There is yet another excerpt from the main project report 1988, page 3.8 para 3.27 which states: -
"However, although drawdown is required for irrigation benefits, the lower the draw down level and the longer the sluicing period, the greater is the loss of power and energy generation".
For further proof of its infeasibility, refer to the KBD's project report June 1988, page 3.9 para 3.31, which states: -
"Chas T. Main etc considered special low-level sluices to achieve very low drawdown. In that case power generation must be discontinued. Thus economic Penalty is large". The above excerpts indicate that the KBD is neither beneficial for irrigation nor for power generation. It also shows that Kalabagh is not the suitable site for a storage dam as prefixed by WAPDA in the TOR for the consultants. It may be investigated for a barrage.
Implications: Refer to the KBD main report page 4.11 para 4.55 which emphasizes 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. As KBD reservoir has the poorest CI ratio in the world, therefore it will rapidly silt up as Tarbela is fast losing its silt trap efficiency after performing 30 years of service.
The muddy Kabul River is also contributing about 110 million tons of silt equal to 0.1 maf annually in addition to 0.2 maf of silt flow from Tarbela Reservoir. Besides all above, the lurking danger of the liquefaction of 200 feet high and about 60 Km long silt island in Tarbela Reservoir would be a potential catastrophe for a down stream storage dam.
The selection and fixation of reservoir site by Wapda with the poorest CI ratio is a great mistake, as it will rapidly silt up. This is why the Kalabagh consultants have shown great concern of rapid silting in the main project report on page 3.5 para 3.17, page 4.12 para 4.57.and page 3.9 para 3.31. Few relevant excerpts are quoted below: -
I. "Upstream of Attock the flood level are sensitive to the amount of sediment so that flood risk will increase with time".
ii. "The future distribution of sediment can be predicted in general terms only and local behaviour will depend on actual sediment inflows, reservoir operation and local flow pattern".
iii. "No immediate solution for sediment management seems to be practically viable".
iv. "The high sediment load carried by the Indus at Kalabagh has an important bearing on the design of Kalabagh Dam and on the operation rules of the reservoir."
v. "In the long run the generation of power will be on run-of-river".
The above excerpts show that the dam is a very short lived project due to rapid silting like the original Sanmenxia Dam in China that was built with mid-level sluicing design and failed with in two years of its construction due to rapid silting and backwater flooding. The Chinese then rebuilt it with low level sluicing design and now its working is perfect. For proof refers to Water Supply and Management, November 5 No: 4/5 pp 351 to 361 of 1981 by Long Yuqian and Zhang Qishun.
The Chinese paper on page 357 supports the unrestricted low level sluicing design concept of the Kalabagh consultants by stating that " the sediment should only be sluiced off the reservoir by lowering the water stage during large floods. The amount of sediment sluiced from the reservoir depends upon the discharge, slope and the duration of flow."
It is surprising that Wapda has instructed the project consultants in the TOR to provide mid-level sluicing design specifically pre-selecting Kalabagh site for the dam so as to create a storage of 9.5 maf at El: 925 with free board at 940. These were the preconditions for the consultants in the TOR. They were not allowed to select a better dam site on the main stem of the Indus River where there is potential for the storage of about 80 maf of water and 40,000 MW of power generation.
These unusual and formidable conditions imposed on the consultants in the TOR by Wapda were kept secret from NWFP as it was flooding Peshawar valley and blocking its sub-surface drainage besides blocking the gateway to NWFP by imposing a wrong design. For confirmation refer to the KBD project report volume N, appendix N. An excerpt from the project report is quoted below: -
Basically design criteria were set during the initial appraisal of the scheme and development outline design. These were based on the requirements of the client through the terms of reference (TOR) or subsequent instructions."
The said instructions in the TOR seriously endangered the whole of Peshawar valley. The proof lies in the fact that the project provided 30 feet high flood protection embankments around Nowshera town, Nowshera cantonment, Akhora Khattak town and other important towns in the valley.
It also affected about 250,000 people as estimated in 1980 besides affecting 180,000 acres of land. Refer to project report volume IX, appendix. U, pages U8 to U10. Also refer to the KBD project report June 1991 page 3.35 and page 15. Again to KBD Executive Summary December 1994, page 23 and to KBD Backwater studies page 6.
On account of the above reasons, the Irsa rejected the hydraulic design of Kalabagh Dam under the Irsa Act with 4:1 majority on 22.10.1996, as the project's hydraulic design was infeasible in the light of para 6 of the Water Accord. After the rejection, Wapda did not file an appeal to the CCI against the decision of Irsa.
The project consultants have clearly established in the feasibility report the design criteria of "low level sluicing" for silt evacuation. Refer to KBD project main report pages 3.5, 3.8 and 3.9. Therefore the design criteria suggested by the project consultants to WAPDA is:
The lower the draw down level, the longer this level is maintained, and the higher the flows then more effective the sluicing will be."
Most unfortunately, Wapda did not agree to accept the design criteria suggested by the KBD project consultants. Wapda argued that in that case storage will be reduced and also the hydropower generation. WAPDA preferred to ignore the very short life span of the dam due to rapid silting, its adverse consequences of water shortage for irrigated agriculture, the flooding of Peshawar valley besides wastage of about $ 8 billion as the cost of the project.
Moreover, there will be a delay of another 25 years for the construction of a new dam on the main stem of the Indus. Surprisingly, Wapda's second priority is the 3.3 maf Akhori Dam an off-channel reservoir already rejected by the World Bank team due to serious foundation problems. Refer to Dr Pieter Lieftnick report Vol:-I pages 269 and 292.
My suggestion to Wapda for the KBD was to adopt, "low level unrestricted sluices with high flows for longer duration." This criteria was suggested for the reasons that the bed level of the Indus River was being flattened by 145 feet (825-680) by the construction of mid-level sluicing Kalabagh Dam that would also block river flow to create storage. As a result, this will slow down the velocity flow on the up stream and drastically reduce stream power.
This will kill the effective silt carrying power of the flow with the result that silt will drop in the wide Attock portion of Kalabagh reservoir. Besides this, the duration of flow is reduced to 50 days. Moreover, another most vital factor to carry silt is of "high flows" that is essentially required to push and evacuate silt.
But this force too is drastically reduced after the diversion of 56500 cusecs of silt free water into Ghazi Barotha Power Channel and dropping its silt in Ghazi barrage pond for deposition at Attock. All silt evacuating factors like steeper slope, high discharge, long duration of flow and unrestricted sluicing at low-level are not available.
However, Wapda can built a low level unrestricted sluicing structure like barrage at the Kalabagh on emergency basis to meet water shortage and to act as balancing reservoir for adjusting and balancing irrigation and water needs. This structure will function like Chashma barrage and will have no silt problem.
Poor power generation: Wapda has falsely shown that power generation from the dam is initially 2400 MW. Actually it is only 350 MW as reported by Dr Pieter Lieftnick in Volume-I of his report. The basic reasons for low power generation are the mid-level sluicing design and the unsuitable site for the dam with the poorest CI ratio in the world. The adoption of wrong sluicing design requires emptying and refilling of the reservoir that takes about four months in a vague attempt to desilt the reservoir.
This reduces power generation by one third to1600 MW. Again, without bringing any change in the hydraulic design, the reservoir retention level for the purpose of reservoir operation is reduced from El: 925 to 915 by 10 feet in a vague attempt to avoid backwater flow and flooding in the Kabul River. This further brings down power generation to 1350 MW.
As a result of wrong mid-level sluicing design giving very low power, Wapda has adopted a cheating method by installing 1000 MW of Thermal power plant attached to the dam to support low hydropower generation from the dam. The actual power generation from the dam therefore comes to 350 MW as worked out by Dr Pieter Lieftnick. Moreover, it is further planned to double the Thermal power to 2000 MW simply to show that the dam produces power. For proof refer to the following:
1. The KBD Executive Summary, December 1984 page 28 and Exhibit-II. The construction cost of thermal station is shown.
2. The KBD Project Report June 1988, pages 4.4, 4.5 and 4.8. This excerpt reveals "The station will operate as a source of base load with Thermal power plant providing additional peak time power as required. Thermal plant will then be used to supplement the hydro-based energy to satisfy the load demand pattern.
3. The KBD main report page 4.8, paras 4.39, 4.4 and 4.1 which states that "Four 500 MW low cost Thermal plant unit have been programmed as shown on diagram No: 10 of the KBD main report.
4. The KBD project report Executive Summary October 1988, pages 41 to 45 " Backwater studies" by Binnie and Partners, Harza, PCR, NES PAK and ACE.
5. The KBD main report pages 42, 43 and 44 besides the report of Dr Pieter Lieftnick.
The writer is former Chairman of Irsa