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Special
Reports/Water Crisis |
Kalabagh consultants suggested barrage
instead of dam
By Fateh
Ullah Khan
This is with reference to Wapda's view titled "Technical
viability of the Kalabagh Dam" published in Dawn on November
29, 2004 in reply to my article titled "In feasibility of
Kalabagh Dam" published by Dawn on November 1, 2004.
 In fact, the Kalabagh Consultants have suggested
unrestricted low-level sluicing design for a structure at
Kalabagh like a barrage. They have stated 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." Reference is invited to the KBD Feasibility Report June
1988, page 3.8 para 3.27.
The sense in the excerpt reveals that the consultants have
clearly suggested a barrage instead of short time,
restricted mid-level sluicing dam as that will not evacuate
silt and make the dam at Kalabagh hydraulically infeasible
due to rapid silting and short life span.
Wapda in reply to my article has used Zean Abid to defend
the restricted mid-level sluicing infeasible hydraulic
design of KBD. The rapid failure due to silting would waste
$8 billion besides wasting time since 1974 to 2025 till
another dam is built at proper site.
As a matter of principle, the KBD project consultants should
have been directed by Wapda for reply to my objections, as
they are the designers and not Zean Abid. This would have
ended all controversies and made the decision easy for the
President.
Wapda has avoided doing so, as it is unreasonably defending
the wrong design and the ridiculous restrictions imposed on
the consultants in the TOR. How can Wapda arbitrarily fix
the dam site at Kalabagh before investigation and then
include this rigid provision in the TOR.
This provision has restricted the consultants not to
investigate a better alternative site on the main stem of
the Indus where there is a potential to develop 40,000 MW of
hydropower and create storage at various sites up to 75 maf.
Wapda directed the consultants to create storage of 9.5 maf
up to elevation 925 with free board at elevation 940 at
Kalabagh site. The investigation was restricted to Kalabagh
site and the consultants could not choose a better site on
the main stem of the Indus River due to restriction.
Wapda's unusual and rigid conditions provided in the TOR are
proved from the KBD Feasibility Report Volume N, appendix N
as follows. "Basically the design criteria were set during
the initial appraisal of scheme and development out line
design. These were based on the requirements of the client
through the terms of reference (TOR) or subsequent
instructions."
How can Wapda set the design criteria of KBD and its outline
design in the TOR before establishing its design
feasibility? Again, how can it fix the 9.5 maf storage
requirement before knowing the hydraulic feasibility and
other conditions? The parochial nature of the TOR sticking
to KBD site indicates hidden trickery for building a dam in
Punjab in spite of submergence of the fertile and highly
populated valley of Peshawar.
The entire statement of Wapda defending KBD is based on
cheating and lying about the project handling from the very
first day. Wapda's parochial attitude is known from its
funny statement claiming that "the importance of KBD is
indicated for being the largest public work in Pakistan's
history and one of the largest multipurpose dams in the
world."
The KBD is shown as the largest and this largeness is shown
as its merit without showing its benefits. Wapda forgets
that Tarbela Dam is the largest that has 11.6 maf storage
that is two times bigger than the 6-maf KBD and Katzarah Dam
with storage of 35-maf is 6 times bigger than KBD with power
generation of 15,000 MW and life span of 1000 years.
Like-wise, KBD is not a multipurpose project due to its
mid-level sluicing design for which it is emptied and
refilled that takes four months a year. It is therefore
neither a fully irrigation nor power project. It is not even
flood control.
On the contrary, it is the most disputed, highly
controversial and totally ridiculous project in the history
after Wapda's most ridiculously planned SCARPs and the NDP
that miserably failed wasting Rs750 billion.
The KBD is therefore considered as a voodoo dam by the three
provinces that are bitterly opposing it for the past 30
years. Nowhere in the world a dam is built on such queer
design that is as queer as that of SCARPs and the NDP.
From the failure of these mega projects it appears Wapda is
bent upon to destroy irrigated agriculture in the Indus
Basin as Punjab is using 45 maf of the accumulated saline-sodic
drainage effluent.
Surprisingly, Wapda has kept the design of KBD secret from
NWFP the province most affected due to flooding of Peshawar
valley. This shows betrayal by a Federal agency. Besides all
this, KBD is a short lived, single purpose replacement
storage to replace storage lost due to silting of Tarbela
and Mangla.
KBD is also not a power project, as it will generate only
350 MW of power and not 2400 MW. Refer to Dr Pieter Lieft
nick report volume-1. In order to support the poor
hydropower generation, Wapda has initially provided 1000 MW
of Thermal plant and then another 1000 MW of Thermal power
plant attached to the dam.
Refer to KBD Executive Summary, December 1984, page 28,
exhibit-II and pages 42, 43 and 44. In these reports, cost
of construction of Thermal power plant is shown. Further
refer to the KBD Project report June 1988, pages 4.1, 4.39,
4.4, and 4.8. Here four 500 MW low cost Thermal plants is
shown in diagram No: 10 of the Feasibility report.
It is noteworthy that a similar mid-level sluicing dam at
Sanmenxia in China had failed with in two years of its
construction due to rapid silting. The Chinese rebuilt it
with a changed design adopting unrestricted low-level
sluicing. Now, it is perfectly working.
Wapda may therefore learn a lesson from the experience of
Sanmenxia Dam before it experiences failure of the KBD.
Reference is invited to a paper on Sanmenxia Dam titled
"Water Supply and Management, No: 4/5 pp 351 to 361 of
November 1981 by Long Tugian and Zhang Qishin.
This paper states "that the amount of sediment sluiced from
the reservoir depends on the discharge, slope and the
duration of flow." Like-wise, the KBD consultants have
stated in the Feasibility Report June 1988, page 3.8 pare
2.7 exactly the same thing but using terminology that "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."
It is clear both the groups of consultants have suggested
that for evacuating silt unrestricted low-level sluicing is
necessary. This is because restricted mid-level sluicing
with short flow duration, lesser discharge and flatter slope
can not evacuate silt from the reservoir.
In case of the KBD, all the hydraulic factors to evacuate
silt are most unfavourable. This is because the Indus River
bed slope is flattened after the construction of mid-level
sluicing dam that reduces stream power to evacuate silt. The
duration of flow to evacuate silt is also reduced from 100
flood days to 50 flood days.
Moreover, the quantity of the Indus flow is also reduced by
the diversion of silt free water of 56500 cusecs into the
GBPC after depositing silt in the Ghazi-barrage pond for
subsequent deposition at Attock.
This shows all vital factors that help evacuate silt are
very adverse. Therefore, rapid silting will take place in
the 3.5 maf mid-level sluicing reservoir of KBD at Attock.
Due to flattening of the Indus bed slope, the velocity flow
or the stream power that carries silt will slowdown and
would not be able to carry silt for evacuation.
As a result, silt will be deposited up stream of the Attock
gorge in the wide spread 3.5 maf KBD reservoir. Out of the
total silt, 40 per cent is the rolling bed load that would
be deposited prior to the remaining silt in the KBD
reservoir.
All this shows that hydraulic condition and the hydraulic
design of the dam plays a very vital part to regulate
sediment. These unfavourable factors affect the feasibility
of the dam due to very short life span and poorest service
value so as to make it economically infeasible.
It is clear that sediment regulation plays a vital role in
the feasibility of the project. In this very context, the
KBD consultants have stated in the Feasibility report 1988,
page 3.5 para 3.27 that " The high sediment load carried by
the Indus at Kalabagh has an important bearing on the design
of Kalabagh and on the operation rules of the reservoir.
If a high proportion of sediment is trapped the storage
volume will rapidly reduce with loss of irrigation benefits
from storage. Such sediment would eventually also cause
unacceptable backwater effect."
The above quoted excerpts mean that silting has an important
bearing on the mid-level sluicing design of the KBD as
adopted. A wrong hydraulic design of mid-level sluicing will
cause rapid silting, backwater flow and flooding of the
whole of the fertile valleys of Peshawar and Mardan, besides
blocking the historic route and the Gateway to NWFP.
The most serious and dangerous is the blockage of the
sub-surface drainage flow from the two valleys towards the
only outlet through Attock gorge. The area up stream of the
Attock gorge is subjected to heavy silting. According to the
KBD consultants this area is most sensitive to silting.
It will receive 0.1 maf silt annually from Kabul River and
0.2 maf from the Indus River. The consultants have estimated
540 million tons of silt flow annually at Attock.
This will hardly give a life span of about 15 to 20 years in
depleting order for the 3.5 maf Attock portion of the KBD
reservoir. Tarbela is fast losing silt trap efficiency.
Moreover, the 200 feet high and 50km long silt delta in
Tarbela reservoir is a lurking catastrophe for Kalabagh
mid-level sluicing dam.
The above quoted excerpt has shown danger of unacceptable
backwater effect due to flooding of Kabul River destroying
the fertile valley of Peshawar. Also refer to KBD project
report volume IX, appendix U, pages U8 to U10 and page 15
besides the KBD Executive Summary December 1994, page 23 and
the report on backwater studies page 6.
These reports show that to prevent Nowshera and other
several towns against flooding, 30 feet high embankment
around these towns will be required for their protection
against backwater flow and flooding.
This will be with reservoir retention level at 925 and free
board at 940. The reduction of level by 10 feet is of no
consequences as the mid-level sluicing design is unchanged.
Moreover, as per 1980 estimate of the KBD report, about
250,000 people will be displaced and 180,000 acres of land
will be affected.
Besides all this, the KBD Feasibility report 1988 shows more
concern about the rapid silting of the reservoir on page 3.5
para 3.17, page 4.2 para 4.57 and page 3.9 para 3.31. A few
excerpts are briefly quoted:
1. "Up stream of Attock gorge the flood level are sensitive
to the amount of sediment so that flood risk will increase
with time."
2. "The future distribution of sediment can be predicted in
general terms only and local behavior will depend on actual
sediment inflows, reservoir operation and local flow
pattern."
3. "No immediate solution for sediment management seems to
be practically viable."
4. "The high sediment load carried by the Indus at Kalabagh
has an important bearing on the design of KBD and on the
operation rules of the reservoir."
5. "In the long run the generation of power will be on
run-of-river."
For an intelligent engineer these numerous indications in
the Feasibility report are more than enough to understand
that mid-level sluicing is wrong, as it will cause rapid
silting.
The project consultants have clearly indicated that for silt
evacuation unrestricted low-level sluicing is required. The
KBD consultants however could not ridicule the client for
failing to understand all these clear indications on account
of the peculiar TOR for the KBD. However, they have clearly
expressed their point of view against mid-level sluicing at
26 places in the feasibility report.
Role of CI ratio in planning dams: In planning dams and
reservoirs at the preliminary stage of desk studies or at
the pre-feasibility stage, the most important of all is to
work out and know the capacity-inflow ratio (CI ratio).
This is vital to estimate and know the life span and service
value of the project to establish its economic viability.
However, it is very painful to know that Wapda has shown
utter ignorance in understanding the CI ratio and its great
importance.
In the first instance, Wapda states that "CI ratio of a
reservoir depends upon the topography of site." Secondly, it
states that "CR ratio is not the only criteria for planning
a technically feasible and economically viable multipurpose
project."
Yet thirdly, another shocking part of the statement is that
"CI ratio of KBD is shown in percentage as 0.069 per cent.
All these gross misconceptions are record breaking news
showing very poor technical understanding in this field.
This is the main reason for awfully mishandling storage
projects by Wapda.
Wapda's statement indicates that it has never heard what CI
ratio means and what role in planning it plays in the
selection of dam site at the pre-feasibility stage as is
evident from its explanation.
It is the CI ratio that indicates the life span, the service
value and the economic viability of storage at the
pre-feasibility stage. The CI ratio is a simple ratio
between the capacity of a reservoir at a site and the
average annual river flow at that site.
In case of KBD portion of the reservoir at Attock on the
Indus, the capacity of the reservoir is 3.5 maf and the
average annual flow is 90 maf. The CI ratio therefore comes
to 3.5:90 or 1:26. This is a ratio and is never expressed in
percentage.
Therefore, Wapda is wrong to show the CI ratio as 0.069 per
cent. Wapda is terribly mistaken to relate CI ratio to the
topography. It never depends on the topography of the site
as wrongly conceived by Wapda.
There are only two factors involved in finding CI ratio,
namely the capacity and the inflow. In case of the KBD, the
CI ratio is the poorest in the world. This is because the
KBD reservoir is located at the tail end of the Indus River
valley drawing a huge inflow of 90 maf of water from a vast
catchment area of 110,000 sq. miles for storage in a meager
reservoir of 3.5 maf.
Therefore, 90 maf of silty water from a vast catchment area
will pass through it thereby depositing the entire silt in
it. It will serve as a silting pond for the huge 90 maf of
the Indus flow. This will cause rapid silting, giving very
short life span with poorest service value.
This renders the KBD economically and hydraulically
infeasible. The important role of CI ratio is that it
indicates the suitability of storage dam at a specific site.
This ratio is the poorest in case of KBD.
This is the reason that the consultants have indicated to
build an unrestricted low-level sluicing structure like a
barrage instead of a dam as the site is not suitable for a
storage dam.
However, Wapda has failed to understand the language of
consultants or has not read the feasibility report
attentively. On the contrary, Wapda is misleading the public
that the "KBD will control one of the world's greatest
catchment area of 110,000 squire miles with 90 maf of the
annual flow. How is that possible to control 90 maf of flow
in a 3.5 maf of the KBD reservoir at Attock?
High barrage: It is shocking to read the poor planning
concept of Wapda saying that "the barrage pond will silt up
rapidly and that the storage capacity of the barrage pond
will be too small to effectively regulate river flow." What
conflicting statements Wapda is giving.
In one case Wapda says something wrong in the next para it
says something quite contrary to that but also wrong. Wapda
knows very well that a barrage is an unrestricted low-level
sluicing structure that passes unrestricted full flood
discharges.
Therefore, it never silts and maintains its waterway clear.
Moreover, it is never built for river regulation. High
barrage as suggested by me is multipurpose. It has several
functions, besides, diverting controlled water into a canal
if desired.
The high barrage at Kalabagh site will create a gross
storage upto 3 to 3.5 maf of water, generate enough power on
run-of-river and would never silt. In addition to all this,
it will function as a "balancing reservoir" or re-regulating
reservoir between irrigation and power water needs. It will
store and meet irrigation water to balance its needs and
also regulate flow to meet peak time power needs as and when
needed.
Therefore, a low-level, unrestricted sluicing structure like
a barrage is suitable at Kalabagh site than a restricted
mid-level sluicing dam. The feasibility report has
repeatedly indicated such a structure at least in 26 paras
of its feasibility report.
The change in design of KBD will save inundation of Peshawar
valley and the cost of compensation of property and
facilities in billions of dollars. To meet Wapda's
vision-2025 water requirements of 27.7 maf, the 35-maf
Katzarah Dam is the only solution as it is the third largest
reservoir dam in the world with a life span of 1000 years.
The 7-maf Basha Dam is technically a very sound project and
far better than Kalabagh in all respects but this too has a
small storage capacity that can serve only as a replacement
storage to replace storage lost due to silting at Tarbela
and Mangla.
Courtesy :
The DAWN
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