Special
Reports/Water Crisis |
Infeasibility of the Kalabagh Dam
By Fateh
Ullah Khan
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
Courtesy :
The DAWN
|
Pakissan.com;
|