Location
Construction & Engineering Hall, Oregon State University
Start Date
27-6-2013 2:10 PM
End Date
27-6-2013 2:30 PM
Description
Over the past decade, stream simulation has become the standard for culvert design in Washington State and in many other states and countries. Stream simulation culverts are based on the assumption that the geologic and hydraulic conditions in natural channels define passage requirements for migrating fish in a given stream and that water crossing structures that imitate these conditions can then achieve those same passage requirements. In early stages of development during the late 1990s, the design method contained various assumptions about how to effectively imitate the channel environment, such as the relationship between the culvert width and the natural channel width. In 2003, a preliminary effectiveness study was done on 19 culverts to explore the veracity of these assumptions. This study expands the initial effort to 50 culverts and includes refined methods and analysis comparing hydraulic characteristics based on cross sections, profile variation, and bed texture between each culvert and its paired reference reach situated in an adjacent section of the natural channel of each stream. Taken as a group, these culverts simulate bed texture, 100-year recurrence interval flood velocity and 2-year flood width, but do not simulate thalweg complexity or other hydraulic metrics. Culvert span, relative to the bank full width of the stream, does not by itself determine whether the culvert simulates the reference reach. Of the 50 culverts, many of which experienced record floods, only one experienced significant bed degradation.
Concurrent Sessions A: Passage Effectiveness Monitoring in Small Streams II - An Evaluation of the Stream Simulation Culvert Design Method in Washington State
Construction & Engineering Hall, Oregon State University
Over the past decade, stream simulation has become the standard for culvert design in Washington State and in many other states and countries. Stream simulation culverts are based on the assumption that the geologic and hydraulic conditions in natural channels define passage requirements for migrating fish in a given stream and that water crossing structures that imitate these conditions can then achieve those same passage requirements. In early stages of development during the late 1990s, the design method contained various assumptions about how to effectively imitate the channel environment, such as the relationship between the culvert width and the natural channel width. In 2003, a preliminary effectiveness study was done on 19 culverts to explore the veracity of these assumptions. This study expands the initial effort to 50 culverts and includes refined methods and analysis comparing hydraulic characteristics based on cross sections, profile variation, and bed texture between each culvert and its paired reference reach situated in an adjacent section of the natural channel of each stream. Taken as a group, these culverts simulate bed texture, 100-year recurrence interval flood velocity and 2-year flood width, but do not simulate thalweg complexity or other hydraulic metrics. Culvert span, relative to the bank full width of the stream, does not by itself determine whether the culvert simulates the reference reach. Of the 50 culverts, many of which experienced record floods, only one experienced significant bed degradation.
Comments
Robert Barnard: For the last 17 years I have been an environmental engineer with the Washington Dept. of Fish and Wildlife specializing in the design of water crossings and fish passage facilities as well as river and estuarine restoration. I am the principle author of WDFW’s Water Crossing Design Guidelines, 2013, and 2 papers on culvert effectiveness.