Presenter/s: Travis Stroth
Symposium Session: 2020 - 02 Considering sediment dynamics in river restoration design
Topics covered: modeling, outside PNW, and sediment transport
The complex nature of river systems presents many challenges to understanding, analyzing, and designing in the context of stream management and restoration. River science and practice has progressed greatly through the years, but still has much room to grow to increase the effectiveness and sustainability of our management and restoration activities. The most efficient path moving forward will need to continue a feedback loop between academia and practice to apply the most current science and guide future research focus areas.
River science and research has recognized and promoted the importance of considering sediment transport dynamics in the context of river restoration design for many years; however, design practitioners have adopted the use of sediment transport concepts and tools for design at widely varying levels within the field. Many potential constraints exist for design projects that limit the consideration of sediment transport, including project timeline-budget and the lack of available data, knowledge of available tools and associated limitations, and confidence in calculations due to uncertainties and often erratic results. Despite constraints, our design team believes sediment transport analyses can still provide a useful line of evidence for design within typical project constraints by utilizing a combination of new concepts and tools and older techniques.
Recent research conducted by Colorado State University for the National Cooperative Highway Research Program (NCHRP) developed new perspectives and tools to consider sediment transport in river restoration design, including a risk-based level of design approach and the spreadsheet-based Capacity-Supply Ratio design tool (CSR Tool). A summary of the key findings from this research will be presented, including how sediment transport analyses relate to the risk-based level of design approach and the development of the CSR Tool, created as part of my Master’s research, to aid in channel design based on reach-scale sediment transport balance and the ‘total effectiveness’ technique. The remainder of the presentation will discuss insights from the application of these techniques and tools for a river restoration design project on the Cache la Poudre River at River Bluffs Open Space near Windsor, Colorado. Monitoring data from pre-post construction and post runoff support the utility of these new techniques as an informative and effective line of evidence in the design process.
The risk-based level of design approach and streamlined programs such as the CSR Tool can provide a useful basis for practitioners to consider sediment transport dynamics in river restoration design within typical project budget and timeline constraints. A discussion of the application of these techniques and tools contributes useful insight into amalgamating the latest scientific research and restoration design practice to support the larger session topic ‘Considering Sediment Transport Dynamics in River Restoration Design: The State of Practice’.