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 fromthe 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. http://www.dawn.com/wps/wcm/connect/dawn-content-library/dawn/the-newspaper/editorial/engineering-failures-680