Alongshore Transport of Large Woody Debris on the Elwha River Delta
Presentation Abstract
In the Elwha River watershed, large woody debris is being tracked in association with the removal of the Glines Canyon and Elwha Dams. In 2011, 25 logs were tagged on the Elwha River delta east of the river mouth along 2 km of beach on the Strait of Juan de Fuca. Logs greater than 3 meters long and 30 cm in diameter were tagged with 3 cm aluminum disks stamped with an identification number. Two comprehensive surveys of the entire delta were conducted in September 2011 and October 2012. 12 shorter surveys across approximately 700 m of the shoreline were also completed. GPS coordinates from all the log surveys were mapped in a geographic information system. 13 logs were missing from the study area by October 2012, either because they were buried by new sediment or moved out of the study area. One additional log recruited to the beach from a separate study tracking 1,700 logs upstream on the Elwha River. For each log observed more than once, the distance traveled between surveys, the rate in meters per day, and the direction of movement in degrees, was calculated. Of the logs that remained in the study area, the maximum distance traveled was 985 meters in 11 months. The minimum rate of movement was 0 m/day and the maximum was 6.6 m/day. The mean movement for all logs in all surveys was 0.4 m/day. The median direction of all movements was 108 degrees. These data are useful in determining the degree to which large woody debris are stable in the intertidal system, and inform questions regarding their role in protecting the beach from erosion. These data may also be used to assess the utility of large wood as a “soft armoring” shore protection solution along drift cells dominated by alongshore transport.
Session Title
Session S-06F: Elwah River Restoration: Evolution of Habitats and Ecosystems During a Dam Removal Project
Conference Track
Restoration
Conference Name
Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)
Document Type
Event
Start Date
1-5-2014 5:00 PM
End Date
1-5-2014 6:30 PM
Location
Room 6C
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Coarse woody debris--Washington (State)--Elwha River Watershed; Shore protection--Washington (State)--Elwha River Watershed
Geographic Coverage
Salish Sea (B.C. and Wash.); Elwha River Watershed (Wash.)
Rights
This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.
Type
Text
Language
English
Format
application/pdf
Alongshore Transport of Large Woody Debris on the Elwha River Delta
Room 6C
In the Elwha River watershed, large woody debris is being tracked in association with the removal of the Glines Canyon and Elwha Dams. In 2011, 25 logs were tagged on the Elwha River delta east of the river mouth along 2 km of beach on the Strait of Juan de Fuca. Logs greater than 3 meters long and 30 cm in diameter were tagged with 3 cm aluminum disks stamped with an identification number. Two comprehensive surveys of the entire delta were conducted in September 2011 and October 2012. 12 shorter surveys across approximately 700 m of the shoreline were also completed. GPS coordinates from all the log surveys were mapped in a geographic information system. 13 logs were missing from the study area by October 2012, either because they were buried by new sediment or moved out of the study area. One additional log recruited to the beach from a separate study tracking 1,700 logs upstream on the Elwha River. For each log observed more than once, the distance traveled between surveys, the rate in meters per day, and the direction of movement in degrees, was calculated. Of the logs that remained in the study area, the maximum distance traveled was 985 meters in 11 months. The minimum rate of movement was 0 m/day and the maximum was 6.6 m/day. The mean movement for all logs in all surveys was 0.4 m/day. The median direction of all movements was 108 degrees. These data are useful in determining the degree to which large woody debris are stable in the intertidal system, and inform questions regarding their role in protecting the beach from erosion. These data may also be used to assess the utility of large wood as a “soft armoring” shore protection solution along drift cells dominated by alongshore transport.
