Release of fine sediment from small reservoirs along mountain channel creates hazards for aquatic biota, and adversely impacts recreational channel use. One means of minimizing the sedimentation hazards associated with these releases would be to specify the discharge regime necessary to flush fine sediments form channel reaches of critical aquatic habit. This research project will use a representative case of recent reservoir sediment release to address the basic objectives of : (1) evaluating the ability of for existing hydraulic models to simulate sedimentation patterns along the type of mountain channels affected by reservoir sediment releases; and (2) developing a conceptual model of reservoir-release sedimentation patterns along mountain channels as a function of channel geometry, discharge, sediment volume, and grain-size distribution. Data on channel response to reservoir-sediment release come form the North Fork Poudre River, Colorado, which had a sediment release in September 1996. Monitoring along the North Fork Poudre River since October 1996 has created a database of changes in velocity distribution, bedload and suspended load transport, and channel geometry as a function of discharge. The research seeks to integrate existing knowledge so as to most effectively apply that knowledge toward mitigating a widespread problem. It will provide resource managers with the information necessary to choose the most appropriate model for a given situation, as well as providing modelers with specific data on the strengths and weaknesses of existing models when applied to sedimentation along mountain channels. It is likely the model study will yield some basic insights into the importance if increased boundary roughness and secondary flow.
