Elsevier

Energy Policy

Volume 35, Issue 12, December 2007, Pages 6526-6534
Energy Policy

Environmental considerations in energy planning for the Amazon region: Downstream effects of dams

https://doi.org/10.1016/j.enpol.2007.07.031Get rights and content

Abstract

The most salient current feature of the electric energy sector in Brazil is the pressing need for expansion. In this context, the hydroelectric resources of the Amazon region are considered a competitive alternative despite the structural problems they entail. These include reliance of new investments and environmental restrictions. Concerning the latter, plans to build large-scale dams in the region have drawn criticism mainly on account of the loss of forest cover in areas flooded by dam reservoirs and the conflicts concerning the relocation of indigenous and riverside communities in the region. This article seeks to contribute to better understanding of the environmental issue in the Amazon by focusing attention on the downstream effects of dams, which have large-scale, hitherto neglected ecological repercussions. The impact of dams extends well beyond the area surrounding the artificial lakes they create, harming rich Amazon wetland ecosystems. The morphology of dammed rivers changes in response to new inputs of energy and matter, which may in turn destroy certain biotopes. This is a remote-sensing-based case study of the Tucuruí hydroelectric scheme in the Amazon state of Pará. Attention is drawn to the need to take into account effects on alluvial rivers downstream from hydroelectric power plants when it comes to making planning decisions, as part of a sustainable energy policy.

Introduction

Besides being prized for its fabulous biodiversity, the Amazon is the world's biggest river basin with a 70,000 MW hydroelectric potential. Confining our focus to Brazilian territory, such outstanding energy potential has transformed the north of the country into a key energy frontier.

In this light, attention should be drawn to the gravity of the degradation caused to the rich ecosystems of the Amazon in the case of hydroelectric schemes. Thousands of square miles will suffer the consequences of this type of intervention, considering the floodplains, i.e. the wetlands of the Amazon Basin. In the context of the Amazon biome, the wetland ecosystems display great biological productivity and contain an enormous variety of resources, despite being smaller than the terra firma areas. Consequently, however important it may be as an indicator, the total area flooded should not be the only criterion considered when planning energy projects (Brasil-Ministério de Minas e Energia, 2006).

In recent decades, debate on the environmental impact caused by hydroelectric schemes has come to the fore. In tandem with this, Brazil's environmental policy has become institutionalized. As a result, greater importance has been ascribed to socio-environmental aspects in the planning of energy sector projects in terms of ensuring that Brazilian environmental policy guidelines conform to national and sectorial standards. Nonetheless, contrary to what one might expect, substantial impacts of large dams are not yet factored into such projects or even formally acknowledged. Attention is thus drawn in this article to the insidious downstream effects of dams, which may extend as far as the delta, encompassing alluvial plains flanking the course of the river.

In Brazil's case, the creation of reservoirs by flooding large tracts of tropical forest has been the prime focus of attention concerning the harmful effects of damming rivers for this purpose. Although the geomorphic adjustment produced by regulating the flow of a river is a long-term harmful process, it determines the maintenance of the habitats affected. Knowledge of the derivative effects of altering the flux of matter and energy in the floodplain is thus of particular importance, and deserves to be included in energy-planning procedures for the region.

Section snippets

The problem of the environmental impacts downstream from dams

The prospect of enhancing exploration of water resources in the Amazon raises considerable environmental problems. With specific reference to areas lying downstream from dams, changes in volume and pattern of water outflow besides the retention of sediment by the dam itself, which may be as high as 95–99% (Williams and Wolman, 1985), are the key variables triggering a variety of geomorphic and geochemical processes. The “clean water” flowing downstream from the dam tends to erode the course and

Environmental constraints on energy policy for the Amazon

The geomorphological evolution of rivers and the way it is affected by engineering work has only recently begun to be understood. Given that the Amazon is a developing energy frontier, environmental variables should be factored into planning the expansion of supply and also serve as a guideline for the region's energy policy.

The ecology of the Amazon has been insufficiently investigated to date. Moreover, neither time nor funds are available for the long-term studies the installation of

Conclusion

If it is true that Brazil needs to harness the hydroelectric potential of the Amazon to promote economic and social development, the electricity sector's planning procedures urgently need reviewing to ensure that the precepts of Brazilian environmental policy are effectively incorporated into decision-making.

One should not neglect the key contribution of hydroelectric power to the national energy grid nor disparage commitments to economic and social development in a developing country like

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