Guidance for Design in Areas of High Bed Mobility Project Theodore G. Cleveland, University of Houston

Laboratory Studies Purpose Purpose Test selected hypotheses regarding causes of bed mobilization. Test selected hypotheses regarding causes of bed mobilization. Test conceptual designs to identify design elements that promote or retard mobilization of bed material. Test conceptual designs to identify design elements that promote or retard mobilization of bed material.

Laboratory Studies Status Status Qualitative proof-of-concept completed last year (videos, etc. presented at RMC). Qualitative proof-of-concept completed last year (videos, etc. presented at RMC). Semi-quantitative model constructed; experiments to begin May Semi-quantitative model constructed; experiments to begin May Video capture on 4 cameras at 30 frames/sec. Video capture on 4 cameras at 30 frames/sec. Pressure/depth on 8 channels at 0.5 reading/sec. Pressure/depth on 8 channels at 0.5 reading/sec. Recently generates 1-5 ft/sec surface velocity. Recently generates 1-5 ft/sec surface velocity.

Laboratory Studies Status Status Semi-quantitative schematic sketch Semi-quantitative schematic sketch Digital Video Camera(s) DVR (Computer) Gravel-bed flume and model Pressure Transducer Wells

Laboratory Studies Status Status Drag-force analysis to estimate velocity Drag-force analysis to estimate velocity Drag Buoyancy Weight Friction/Restraint h

Laboratory Studies Status Status Drag-force analysis to estimate velocity Drag-force analysis to estimate velocity Ratio of step height to radius Log(Velocity) at rotation r=0.01 r=0.10 r=1.00

Laboratory Studies Status Status In the lab placing the bed is easier with bed immersed. In the lab placing the bed is easier with bed immersed. During recent placement the stabilized bed exposed 5-6 cm particles to 5 ft./sec water velocities. During recent placement the stabilized bed exposed 5-6 cm particles to 5 ft./sec water velocities. Drag-force analysis suggested such materials should remain stable. - Thus the theory gives us a tool to select flow speeds and particle sizes to study in the lab. Drag-force analysis suggested such materials should remain stable. - Thus the theory gives us a tool to select flow speeds and particle sizes to study in the lab.

Laboratory Studies Next steps Next steps Develop expertise to generate repeatable flow velocities (not trivial). Develop expertise to generate repeatable flow velocities (not trivial). Select and place small but visible particles to serve as mobile material; larger material to serve as porous substrate bed - it is not intended to move. Select and place small but visible particles to serve as mobile material; larger material to serve as porous substrate bed - it is not intended to move. Conduct fully instrumented experiments to test utility of drag force model. Conduct fully instrumented experiments to test utility of drag force model. Conduct fully instrumented experiments to relate hydraulic measurements (geometry, flow depth) to mobility characteristics. Conduct fully instrumented experiments to relate hydraulic measurements (geometry, flow depth) to mobility characteristics.

Laboratory Studies Next steps Next steps Insert small (concrete and wire) low water crossing models in a variety of shapes to evaluate model ability to allow or restrain passage of bed material. Insert small (concrete and wire) low water crossing models in a variety of shapes to evaluate model ability to allow or restrain passage of bed material. Write report documenting these activities as well as additional activities used to guide field investigations. Write report documenting these activities as well as additional activities used to guide field investigations.

Laboratory Studies