Optimising woody debris dam design for flood risk management

This study examines how variations in engineered woody debris dam designs affect bed morphology. Pools and riffles, formed by these dams, create varied flow velocities and depths, dissipating energy and mitigating downstream flood risk. Understanding their hydraulic effects on scour and deposition remains limited. Laboratory flume experiments were conducted at two discharges, using two structure designs, each comprising three wooden cylinders with varying bed-to-base gaps. Digital Elevation Models were generated using a Kinect v1.0 and Matlab. To verify localised velocities and bed shear stress values, a computational flume was constructed using Jacobs Flood Modeller. Findings showed that the 2D model replicated the physical experiments effectively, highlighting increased bed shear stress downstream of the structure and corroborating the location of maximum scour depth. Results indicated that structures close to the bed increased scour depth beneath them, enlarging the wetted area and reducing their effectiveness in slowing the flow.