The Taunsa Barrage, the World Bank and the Pakistan floods

Engineering failures
By Mushtaq Gaadi
Editorial in Dawn (Pakistan)
Monday, 16 Aug, 2010
www.dawn.com/wps/wcm/connect/dawn-content-library/dawn/the-newspaper/editorial/engineering-failures-680

THE devastating floods in Pakistan have once again ignited public debate
on the necessity of new water reservoirs in the country. The proponents
of Kalabagh Dam, including some prominent politicians, TV anchorpersons,
and Punjab water engineers, hold that if Kalabagh dam had been built, we
would not be facing the present disaster wreaked upon millions of people
in the Indus Valley.

According to them, the Kalabagh dam or any other water engineering
project should not be politicised because these issues are essentially
'technical'. Decisions on such vital issues should be left to the wisdom
of engineers and technical experts.

Implicit in this argument are three underlying assumptions, all three of
which are incorrect. First, it is assumed that 'technical' engineering
interventions in natural (water) systems have nothing to do with
politics. Second, that the control of river flows through engineering
structures is the best possible way to control flooding. Third, that the
knowledge of the engineering community is conclusive and beyond any
critical scrutiny. Nonetheless, mounting evidence and experiences
throughout the world suggest that these assumptions are not only
reductionist but also in fact part of the problem of river basin management.

A closer analysis of the present flood and flood-related events
experienced at/around Taunsa barrage furnishes us with some
counter-intuitive, and indeed, scandalous evidence: the very structures
meant to control flooding have partially caused and definitely
exacerbated the flood problem itself.

The flood trauma started with the breach of the eastern marginal
embankment in the upstream of Taunsa barrage. The breach caused the
Indus to outflank the barrage and the river carved out a new channel to
the left of its original course. Very shortly, floodwater flowing down
this new channel found its way into the extensive network of irrigation
canals on the left side. Consequently, masses of roiling, churning
floodwater are now rushing through and inundating relatively higher
ground which was rarely inundated by the Indus. Nature is responsible,
yes. But we must not overlook the role that engineering structures have
played in transforming the present floods into an enormous disaster
unparalleled in the history of this region.

Taunsa barrage is one of the most vulnerable diversion structures built
across the Indus River. Therefore, it was recently rehabilitated and
modernised with the help of a World Bank loan of $144m. The project was
approved and implemented on an emergency basis so that the barrage could
be kept functional. All that money has been washed right away. The Bank
is now involved in similar costly rehabilitation works at Jinnah
barrage, the latter also failing to withstand these recent floods.
Jinnah barrage's staff was compelled to blow up the embankments on the
right bank resulting in widespread inundation and heavy damages to the
under-construction hydropower project also stationed there. The Bank has
plans to undertake similar rehabilitation projects at other barrages in
Punjab.

When the rehabilitation of Taunsa barrage was being planned in early
2004, local civil society objected to the dominant engineering
perspective and asked the Bank and the irrigation department to pay more
attention to mitigating the barrage-induced alterations in river
hydrology and problem of sediment deposition, a phenomenon which has
made the flood protective structures susceptible to regular failure. In
this regard, a memorandum was submitted to the then country director of
the World Bank. The memorandum asked both the Bank and the provincial
government to appoint an independent review commission to ascertain the
nature and scope of rehabilitation works at Taunsa barrage. However, the
country director turned down the demand in a separate press conference.

The main problem with Taunsa barrage is the rising riverbed owing to
huge sediment deposition in the upstream areas. Before the construction
of dams and barrages, the Indus used to transport about 250 megatons
(Mt) of sediment annually, mostly silt and clay, to the Arabian Sea.
This helped in the development and nurturing of freshwater mangroves
prior to the phase of dam construction. By 1974-75, this had fallen to
about 100 Mt per annum and it is believed the present rates are
negligible. Taunsa barrage traps huge sediments left over from the
upstream storage and diversion structures. Moreover, the pond area is
additionally fed annually with large amounts of silt eroded from the
highly degraded catchment areas of the Suleiman Range. These heavy silt
loads are transported through western tributaries (hill-torrents) of the
Indus River.

The obstruction of great volumes of water together with the suspension
of a large amount of sediment has complicated the flooding problem at
Taunsa barrage. The riverbed levels are now higher than they have ever
been. The construction of a series of protective levees and dykes has
also contributed to raising the riverbed and the sedimentation of
upstream areas. These changes forced the river into developing an
oblique flow line and establishing a more tortuous course. Consequently,
it now spends its vigour on eroding the vulnerable banks. Moreover, the
rising riverbed levels have rendered protective levees and river
training works ineffective. Under the rehabilitation project, the crust
level of the barrage was raised by one foot so that silt entry into the
right bank canal could be controlled. The protective embankments were
also to be raised correspondingly but criminal negligence in this regard
resulted in no such measures being undertaken. Similarly, local accounts
and media reports suggest that the barrage staff has failed to properly
operate the newly installed motorised hoisting system.

According to these reports, 10 gates were not fully opened which, if
true, turned out to be the main cause of the flood disaster. The truth
of these reports must be ascertained, but if they hold, then an official
inquiry must be held into the incident and people held accountable.The
nature of the debate on the Kalabagh dam in the aftermath of the flood
disaster is depressingly flawed. Not only is this debate politically
divisive for an already fragile federation, it also covers up the story
of how engineering failures have contributed to this disaster.
Reconstruction without the benefits of an honest analysis would be
tantamount to recreating this same situation, or even worse, in the future.

The writer is a native of Taunsa and teaches at Quaid-i-Azam University,
Islamabad.
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