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Civil Engineering is a multi faceted discipline with a vast reach. Hence, it is prone to controversies. Apart from institutionalized corruption – as it is the case at least in some parts of the world – it invites professional and technical controversies. The profound effects of these controversies on humanity makes sense for science enthusiasts and common people alike to study what goes wrong sometimes with some civil engineering projects.
Large Dams
Perhaps large dams are the single most controversy prone type of structure. Dams affect the ecology of the river, its catchment area, as well as the downstream stretch of the river and even the sea / lake or major river, in which it confluences.
The cost benefit analysis of any large project is a very crucial phase before implementation. The various costs of project and the direct and indirect benefits accrued are compared to assess the net benefit or revenue. It’s not uncommon for governments to take up certain projects not for revenue but out of social commitments.
In case of large dams, in most cases, the designers (civil engineers) and financiers (governments, corporate houses or funding agencies) trumpet the benefits that accrue from the dam projects. They do not forget to mention the indirect benefits to society like the generation of wealth leading to more consumer demand and more employment opportunities and such and such.
But when it comes to the environmental and ecological costs, seismic dangers, drop in water quality, water logging costs and rehabilitation and resettlement costs, they mislead or just ignore. Many of the existing large dams would turn out to be developmental blunders, if all these costs are also added. The socioeconomic costs of resettlement and rehabilitation of dam-replaced people is a full scale extra dimension.
The impounding of water starts as soon as a minimum obstruction is laid across the river and its ill effects begin to show up soon. While the completion of main dam itself, its ancillary structures, power houses, canal systems, water distribution systems etc take many years to complete.
Some times, as happened in the case of Narmada dam in India, the cost of pipelines and other distribution systems are reportedly not included in project cost but the benefit of providing drinking water to drought prone areas located 100s of kms away is!
Sometimes, it takes decades after impounding, for the dam project to be finished and to start giving full planned benefits but the analysis is often made as if the submergence and accrual of benefits begin simultaneously. All these help exaggeration of benefits.
In catchment areas of many large dams, the reservoir profile is such that, at the top levels of dam, with each unit increase in dam height, the increase in storage is MUCH LESS compared to the area of submergence. But the engineer, contractor and politician lobby is so powerful and favour raising the dam height to the extent possible.
Many large dams meant for water supply to nearby towns and cities, often fell short of demands and shown poor economic sense. Even, the water quality in the river has appreciably changed, to the bad in many cases, after impounding of water.
Loss of sites of archaeological importance is another drawback of significance, given the fact that the river valleys are cradles of civilizations, since ages, worldwide.
Dam induced silting in reservoir area and regular silting, consequent loss of intended benefits, often derail expectations. Development of dam site areas is often accompanied by accelerated deforestation of the catchment, in which case the increased silting may scuttle the dam benefit goals, by cutting dam’s life more than expected.
These are only a few of purely technical controversies. Besides these, large dams also have socio economical and environmental drawbacks. Also, the so-called benefits of hydropower from large dams leave much scope for debate. Let’s consider these in next parts.
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