Engineering and Ecological Aspects of Dam Removal-An Overview

摘要

Decommissioning and removing dams has emerged as one of the central foci of the new millennium for infrastructure management, river conservation, and the restoration of fisheries populations (American Institute of Biological Sciences (AIBS) 2002; Heinz Center 2002). Anadromous, catadromous, and adfluvial species (Figure 1) are especially impacted by dam decommissioning and removal. It represents arguably the most powerful tool and largest opportunity for restoration of aquatic ecosystems and communities that currently exists. Several phenomena underlie this development: ' High dam densities and the aging of dam infrastructure. Of large dams, 85 percent will have exceeded their design lifespans by 2020 or soon thereafter (Federal Emergency Management Agency (FEMA) 2001). Though inventories are poor, dams exist at much higher densities than many realize (Figure 2). ' Threats or occurrences of dam failures (Figures 3, 4, 5). In 2000 and 2001, 520 dam incidents and 61 dam failures occurred; the American Society of Civil Engineers (ASCE) gave dam management and safety a grade of D in the last two editions of its Report Card for America's Infrastructure (ASCE 2002).