Effects of Dam Removal: An Approach to Sedimentation.

In recent years hydraulic structures such as dams have been removed due to deterioration, increased maintenance cost or obsolescence. Investigation of the hydraulic, hydrologic, and sediment transport consequences of the removal of these structures have been very limited, thus necessitating the establishment of analytical techniques and procedures to adequately predict these effects. To properly evaluate the development of techniques and procedures, a model must be selected that closely simulates the actual behavior of the phenomenon being modeled. A mathematical HEC-6 was selected because of its success in the prediction of sediment transport when applied to a wide variety of cases. The removal of the Washington Water Power Dam on the Clearwater River near Lewiston, Idaho, was selected for study. Procedures and techniques of calibration and verification developed, comparison of actual and predicted volume of sediment transported, where the sediment scoured or deposited, and their rates are presented. There is discussion of the applicability of the model to this type of problem, limitations of a one-dimensional model, and interpretation of the results. Author