Working with wood in rivers in the Western United States

Recognition of the important physical and ecological roles played by large wood in channels and on floodplains has grown substantially during recent decades. Although large wood continues to be routinely removed from many river corridors worldwide, the practice of wood reintroduction has spread across the United States, the United Kingdom and western Europe, Australia, and New Zealand. The state-of-science regarding working with wood in rivers was discussed during a workshop held in Colorado, USA, in September 2022 with 40 participants who are scientists and practitioners from across the USA, UK, Europe, and Japan. The objectives of this paper are to present the findings from the workshop; summarize two case studies of wood in river restoration in the western United States; and provide suggestions for advancing the practice of wood in river management. We summarize the workshop results based on participant judgements and recommendations with respect to: (i) limitations and key barriers to using wood, which reflect perceptions and practicalities; (ii) gaps in the use of large wood in river management; (iii) scenarios in which wood is generally used effectively; and (iv) scenarios in which wood is generally not used effectively. The case studies illustrate the importance of the local geomorphic context, the configuration complexity of the wood, and the potential for modification of river corridor morphology to enhance desired benefits. Moving forward, we stress the importance of collaboration across disciplines and across communities of research scientists, practitioners, regulators, and potential stakeholders; accounting for stakeholder perceptions of the use of large wood; and increasing non-scientist access to the latest state-of-science knowledge

Full spectrum analytical channel design with the capacity/supply ratio (CSR)

2017 Spring.Includes bibliographical references.Analytical channel design tools have not advanced appreciably in the last decades, and continue to produce designs based upon a single representative discharge that may not lead to sediment continuity. It is beneficial for designers to know when a simplified design may be problematic and to efficiently produce alternative designs that approximate sediment balance over the entire flow regime. The Capacity/Supply Ratio (CSR) approach, an extension of the Copeland method of analytical channel design for sand channels, balances the sediment transport capacity of a design reach with the sediment supply of a stable upstream reach over the entire flow duration curve (FDC) rather than just a single discharge. Although CSR has a stronger physical basis than previous analytical channel design approaches, it has not been adopted in practice because it can be a cumbersome and time-consuming iterative analysis without the use of software. I present a novel design tool that was developed using the Visual Basic for Applications (VBA) programming language in Excel® and produces stable channel slope/width combinations based on the CSR methodology for both sand- and gravel-bed streams. The CSR Stable Channel Design Tool's (CSR Tool) code structure was based on Copeland's method in SAM and HEC-RAS (Hydrologic Engineering Center – River Analysis System) and was tested with a single discharge to verify outputs. Eighteen sand-bed rivers were investigated with the tool in a comparison of designs based on the CSR approach and five single-discharge metrics: the effective discharge (Qeff) or discharge that transports the most sediment over time, the 1.5-year recurrence interval discharge (Q1.5), bankfull discharge (Qbf), and the discharges associated with 50th (Qs50) and 75th (Qs75) percentiles of the cumulative sediment yield curve. The Qs50 and Qs75 single-discharge designs match the CSR output most closely followed by the Qbf and Qeff. The Qeff proved to be the most inconsistent design metric because it can be highly dependent on the binning procedure used in the effectiveness analysis. Furthermore, I found that the more rigorous physical basis of the CSR analysis is potentially most important in designing "labile' channels with highly erodible substrate, high perennial flow "flashiness', low width-to-depth ratio, and high incoming sediment load. The CSR Tool provides a resource for river-restoration practitioners to utilize process-based design techniques that can promote more reliable and sustainable designs for dynamic fluvial systems

Dense Nuclear Matter Equation of State from Heavy-Ion Collisions

The nuclear equation of state (EOS) is at the center of numerous theoretical and experimental efforts in nuclear physics. With advances in microscopic theories for nuclear interactions, the availability of experiments probing nuclear matter under conditions not reached before, endeavors to develop sophisticated and reliable transport simulations to interpret these experiments, and the advent of multi-messenger astronomy, the next decade will bring new opportunities for determining the nuclear matter EOS, elucidating its dependence on density, temperature, and isospin asymmetry. Among controlled terrestrial experiments, collisions of heavy nuclei at intermediate beam energies (from a few tens of MeV/nucleon to about 25 GeV/nucleon in the fixed-target frame) probe the widest ranges of baryon density and temperature, enabling studies of nuclear matter from a few tenths to about 5 times the nuclear saturation density and for temperatures from a few to well above a hundred MeV, respectively. Collisions of neutron-rich isotopes further bring the opportunity to probe effects due to the isospin asymmetry. However, capitalizing on the enormous scientific effort aimed at uncovering the dense nuclear matter EOS, both at RHIC and at FRIB as well as at other international facilities, depends on the continued development of state-of-the-art hadronic transport simulations. This white paper highlights the role that heavy-ion collision experiments and hadronic transport simulations play in understanding strong interactions in dense nuclear matter, with an emphasis on how these efforts can be used together with microscopic approaches and neutron star studies to uncover the nuclear EOS

Dense nuclear matter equation of state from heavy-ion collisions

International audienceThe nuclear equation of state (EOS) is at the center of numerous theoretical and experimental efforts in nuclear physics. With advances in microscopic theories for nuclear interactions, the availability of experiments probing nuclear matter under conditions not reached before, endeavors to develop sophisticated and reliable transport simulations to interpret these experiments, and the advent of multi-messenger astronomy, the next decade will bring new opportunities for determining the nuclear matter EOS, elucidating its dependence on density, temperature, and isospin asymmetry. Among controlled terrestrial experiments, collisions of heavy nuclei at intermediate beam energies (from a few tens of MeV/nucleon to about 25 GeV/nucleon in the fixed-target frame) probe the widest ranges of baryon density and temperature, enabling studies of nuclear matter from a few tenths to about 5 times the nuclear saturation density and for temperatures from a few to well above a hundred MeV, respectively. Collisions of neutron-rich isotopes further bring the opportunity to probe effects due to the isospin asymmetry. However, capitalizing on the enormous scientific effort aimed at uncovering the dense nuclear matter EOS, both at RHIC and at FRIB as well as at other international facilities, depends on the continued development of state-of-the-art hadronic transport simulations. This white paper highlights the essential role that heavy-ion collision experiments and hadronic transport simulations play in understanding strong interactions in dense nuclear matter, with an emphasis on how these efforts can be used together with microscopic approaches and neutron star studies to uncover the nuclear EOS