ASCE MOP 122

Abstract

From past experience with dam construction, researchers have learned a great deal about the adverse effects dams have on river ecosystems. Also, considerable knowledge has been gained pertinent to the removal of dams, especially small ones. These experiences can collectively guide and improve fundamental knowledge regarding future dam removal, and can create opportunities for advancing the sciences of ecology, hydrology, and geomorphology. In recent years, many studies have been conducted in the fi eld of dam removal and there is thus a defi nite need to disseminate reports on these research efforts and encourage the scientifi c community to evaluate the pertinent theories and practices. Some of the ecological impacts related to dam removal, mainly on fi sh and other aquatic species, were documented in a landmark issue of BioScience, which is published by the American Institute of Biological Sciences (AIBS) (AIBS 2002). In comparison, this manual primarily focuses on the geomorphologic impacts associated with dam removal, including the effects of sediment transport, aggradation, and degradation on the physical characteristics of rivers. <br>The organization of this manual is based on the different topics presented by the contributors and the feedback provided by the ASCE/ EWRI Task Committee on Sediment Dynamics Post Dam Removal. In July 2005, this ASCE/EWRI Task Committee, led by Laura Wildman, Chair, Glastonbury, Connecticut; Cassie Klumpp, Vice Chair, Denver, Colorado; Blair Greimann, Secretary, Denver, Colorado; and James Mac- Broom, Committee Member, Cheshire, Connecticut, brought together many national experts, both in research and practice, on the specifi c topic of sediment dynamics post-dam removal. The authors represented federal agencies, universities, consulting fi rms, environmental nonprofi t organizations, federal and academic research laboratories, as well as state agencies; they included engineers, geomorphologists, academic researchers, hydraulic/hydrologic modelers, model developers, ecologists, and fi sheries biologists. The ultimate goal of the ASCE/EWRI Task Committee was a state-of-the-art publication including invited papers on dam removal compiled to a manual. <br>The papers were peer-reviewed and refl ect the many and various regional and project-specifi c perspectives related to this topic. Subjects covered included physical models, numerical simulations, specifi c case studies, decision-making processes, individual dam issues, geomorphic changes, channel bed evolution, downstream sediment transport, ecological implications, lessons learned from case studies, and sediment quality. Further, these papers encompassed wide variety in sediment composition, hydrologic region, and project scale. This manual is a compilation of the most relevant and innovative papers on dam removal, and thus presents the many national ongoing efforts and the state-of-the-science/practice in the fi eld of sedimentation as it relates to river dynamics post-dam removal.