Road crossings at rivers and streams can create barriers to the movement of migratory fish when they are improperly designed or constructed. Washington State is home to several threatened species of salmon and trout, including bull trout, and recovery plans for these fish include repairing or replacing culverts that currently block their passage. The state is currently looking to replace approximately 1,000 culverts at an estimated cost of $2.45 billion. As engineers re-design these culverts, which typically have a service life of 50-100 years, it will be important to consider how changing climate conditions will impact streams in the region. Climate change is projected to increase peak streamflows, and therefore widen stream channels, [...]
Summary
Road crossings at rivers and streams can create barriers to the movement of migratory fish when they are improperly designed or constructed. Washington State is home to several threatened species of salmon and trout, including bull trout, and recovery plans for these fish include repairing or replacing culverts that currently block their passage. The state is currently looking to replace approximately 1,000 culverts at an estimated cost of $2.45 billion. As engineers re-design these culverts, which typically have a service life of 50-100 years, it will be important to consider how changing climate conditions will impact streams in the region. Climate change is projected to increase peak streamflows, and therefore widen stream channels, across much of Washington State over the course of the 21st century. Incorporating these climate change considerations into culvert removal and redesign will be key to ensuring the long-term resilience of those capital investments and the success of stream habitat restoration efforts.
The goal of this project is to support climate-resilient design for culvert and fish habitat restoration projects in Washington. Through collaboration with the Washington Department of Fish and Wildlife (WDFW), researchers will develop an interactive website that will provide the best available science on projections of future stream discharges and channel width for the state. These projections will be provided at the site level, and will also include estimates of the probability that a given culvert will fail to meet the design standard for fish passage during its service life. While WDFW has developed an internal tool to support climate-resilient culvert design, the tool needs to be updated to reflect the latest science. The purpose of this project is to address those issues and increase the utility and accessibility of the existing web tool. The final, publicly-available website will support engineers, landscape architects, restoration ecologists, and others involved in the design of culverts and stream restoration projects in Washington State.
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Purpose
The purpose of this project is to create a user-centered website that allows engineers and restoration ecologists to obtain probabilistic climate change information for salmon habitat restoration and culvert construction projects. Site-level information on hydrology and geomorphology is essential for culvert design and salmon habitat restoration plans. Numerous studies show that climate change will increase peak stream flows, thereby widening stream channels over much of Washington State. As a result, culverts that are not designed for future flows are at risk of failing over their lifetime. WDFW recently developed an intranet site for climate-smart culvert design that provides site-level projections of future changes in streamflow and channel width, while the Climate Impacts Group (CIG) has piloted an approach for estimating the probability of exceeding culvert design specifications over a structure’s expected service life. New climate projections are also available for the region, but have not been incorporated into WDFW’s intranet site. The purpose of this project is to develop a user-centered web tool, based on the best available science, that provides design-relevant climate change information for salmon habitat restoration and culvert construction projects. The proposed work will focus on the four following tasks: 1. Convene prospective users to guide the development of an internet-based tool for climate-smart culvert design that is both intuitive and functional. 2. Incorporate CIG’s approach to estimating the probability of exceeding culvert design specifications into WDFWs internet site. 3. Support salmon habitat restoration ecologists to design for future conditions by developing projections of future changes in extreme flows (e.g., 10- and 200-year flood) for incorporation into the web tool. 4. Increase the quality of WDFW’s channel width projections by updating to the most current climate projections and updating the outdated land cover layer.
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(1) Objectives/Justification: Climate change is projected to significantly alter streamflow in much of the Pacific Northwest. Our objective is to support climate-resilient design in culvert and habitat restoration projects. Building on past collaborations, we will work with engineers and restoration ecologists to design an online tool that provides up-to-date site-level projections of changes in stream discharge and channel width caused by climate change. (2) Background: WDFW is the state agency in Washington that has regulatory authority over culvert construction. WDFW has an internal-only site that agency staff can use to obtain site-level projections of future changes in stream discharge and channel width, and CIG has piloted a probabilistic approach to evaluating culvert design. We are proposing to combine these tools to avoid confusion, work with prospective users to improve usability, and update the results with new climate and hydrologic modeling. (3) Procedures/Method: WDFW has staff and resources to develop new internet site. See Wilhere et al. (2017a, 2017b) for a description of methods used to obtain projected future changes in stream discharge and channel widths. We will use the MACA downscaled climate projections (Abatzoglou and Brown 2012); the hydrologic modeling approach will build on the Integrated Scenarios for the Future Northwest Environment project (Mote et al. 2014). (4) Expected Products and Information/Technology Transfer: Product: A publicly-accessible online tool that will enable a user to click on a point on a map and in return get projected changes in channel width and stream discharges, with the option to estimate the probability that a culvert will fail to meet design specifications. Technology Transfer: We will work with prospective users throughout the project to test usability and information clarity. In addition to regular collaboration with prospective users, we will increase awareness of the tool through conference presentations and webinars. (5) Personnel/Cooperators/Partners. PI: Guillaume Mauger, Climate Impacts group Co-PI: George Wilhere, Senior Research Scientist, WDFW Cooperators: WDFW IT staff, WDFW climate coordinator, WDFW research scientists Partners: The following partners will support the design of the tool: Jeff Hugdahl, WDFW; Kirsten Harma, Chehalis Basin Lead Entity; Lara Whitely Binder, King County; Larry Wasserman, Swinomish Tribe; Jon Riedel and Carol MacIlroy, Skagit Climate Science Consortium (SC2); and Davia Palmeri, Oregon Department of Fish and Wildlife (ODFW).