Location

UMass Amherst

Event Website

http://fishpassage.ecs.umass.edu/Conference2012/

Start Date

5-6-2012 1:50 PM

End Date

5-6-2012 2:10 PM

Description

Selection of culvert width is driven by project objectives, site characteristics and stream type and while not the only consideration, significantly guides culvert bed and bank design. In stable channels, almost all standard guidelines recommend a width that varies from bankfull width or larger and many vary the guideline by entrenchment ratio. In streams that are unstable, sizing a culvert to be a bit larger or smaller than the creek width may be a design need as it comes to equilibrium conditions. Once the bankfull width is determined, a selection of culvert width larger than bankfull results in the need to include stable banks to maintain the width to depth ratio of the stream. Within the design process, this may result in a larger culvert than anticipated due to the size of rocks necessary to maintain stable banks. Throughout the process of width selection, preventing low flow fish passage issues, problematic aufeis formation and sediment deposition is paramount and may result in selection of a smaller or larger culvert than originally desired. Low flow channels in the bed also need to be stable, and the ratio of the low flow channel to channel width can be maintained by structures such as boulder clusters or rock bands within the channel bed. In consideration of culvert width, the purpose of streambanks should be fully evaluated. For instance, are the streambanks necessary for fish habitat or can rock clusters or other roughness features perform the same function? Is there a need to provide other ecological functions such as animal passage along the banks or would a floodplain culvert accomplish the same need? These questions and more must be answered and no one standard can fit all situations.

Comments

William (Bill) Rice is a hydrologist and engineer for Region 7, U.S. Fish and Wildlife Service in Anchorage, Alaska. For the past eight years, he has conducted geomorphic and habitat assessments while designing and constructing over 70 fish passage and stream restoration projects. Bill also conducts a popular 2-day fish passage workshop across Alaska, and participates on national fish passage initiatives. He has a Bachelor's of Science degree in Geology and Geological Engineering from the Colorado School of Mines and Masters of Science degree in Watershed Science from Colorado State University.

Share

COinS
 
Jun 5th, 1:50 PM Jun 5th, 2:10 PM

Session C2 - Bed and Bank Design Considerations When Selecting Culvert Width

UMass Amherst

Selection of culvert width is driven by project objectives, site characteristics and stream type and while not the only consideration, significantly guides culvert bed and bank design. In stable channels, almost all standard guidelines recommend a width that varies from bankfull width or larger and many vary the guideline by entrenchment ratio. In streams that are unstable, sizing a culvert to be a bit larger or smaller than the creek width may be a design need as it comes to equilibrium conditions. Once the bankfull width is determined, a selection of culvert width larger than bankfull results in the need to include stable banks to maintain the width to depth ratio of the stream. Within the design process, this may result in a larger culvert than anticipated due to the size of rocks necessary to maintain stable banks. Throughout the process of width selection, preventing low flow fish passage issues, problematic aufeis formation and sediment deposition is paramount and may result in selection of a smaller or larger culvert than originally desired. Low flow channels in the bed also need to be stable, and the ratio of the low flow channel to channel width can be maintained by structures such as boulder clusters or rock bands within the channel bed. In consideration of culvert width, the purpose of streambanks should be fully evaluated. For instance, are the streambanks necessary for fish habitat or can rock clusters or other roughness features perform the same function? Is there a need to provide other ecological functions such as animal passage along the banks or would a floodplain culvert accomplish the same need? These questions and more must be answered and no one standard can fit all situations.

http://scholarworks.umass.edu/fishpassage_conference/2012/June5/26