Streaming Media
Presentation Abstract
The Washington State Department of Ecology performed an erosion hazard assessment for the coast of Clallam County, WA, from Cape Flattery to Diamond Point as part of a project for hazard mitigation planning funded by the Washington State Military Department Emergency Management Division. This shoreline receives among the highest wave energy for the Salish Sea and its rugged and remote coastline creates challenges for shoreline change assessments outside of developed areas. NAIP imagery from multiple years was compared to determine if an erosion risk was present based on vegetation line retreat. Oblique shoreline photos were used to help resolve imagery where shadows or image quality distorted the coast. Other signs of erosion such as vegetation loss on the bluff face or apparent undercutting of the bluff were also noted. Each reach was assigned a designation that best describes the vegetation line trend and erosion risk in the area with categories including: change is less than noise level, accreting, human-induced change, or erosion hazard area. In locations where erosion was detected from the imagery, a change rate averaged over approximately ten years was calculated based on the position change of the vegetation lines. Areas where signs of erosion were detected but the shoreline or vegetation line was indiscernible due to image quality or thick tree cover were also considered erosion hazard areas, and noted as a potential risk even if change rates could not be calculated. The results of the hazard assessment are available in an interactive web map which includes the designation, change rates for erosion hazard areas, and additional information that was observed from the imagery. This map is available to the public and can aid in coastal planning and risk assessments at local or regional levels.
Session Title
Poster Session 3: Land - Water Connections
Conference Track
SSE14: Posters
Conference Name
Salish Sea Ecosystem Conference (2022 : Online)
Document Type
Event
SSEC Identifier
SSE-posters-461
Start Date
27-4-2022 4:00 PM
End Date
27-4-2022 4:30 PM
Type of Presentation
Poster
Genre/Form
conference proceedings; presentations (communicative events); posters
Subjects – Topical (LCSH)
Coast changes--Washington (State)--Clallam County; Beach erosion--Washington (State)--Clallam County; Shore protection--Washington (State)--Clallam County
Geographic Coverage
Clallam County (Wash.)
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.
Type
Text
Language
English
Format
application/pdf
Included in
Fresh Water Studies Commons, Marine Biology Commons, Natural Resources and Conservation Commons
Coastal erosion hazard assessment results along Clallam County, WA
The Washington State Department of Ecology performed an erosion hazard assessment for the coast of Clallam County, WA, from Cape Flattery to Diamond Point as part of a project for hazard mitigation planning funded by the Washington State Military Department Emergency Management Division. This shoreline receives among the highest wave energy for the Salish Sea and its rugged and remote coastline creates challenges for shoreline change assessments outside of developed areas. NAIP imagery from multiple years was compared to determine if an erosion risk was present based on vegetation line retreat. Oblique shoreline photos were used to help resolve imagery where shadows or image quality distorted the coast. Other signs of erosion such as vegetation loss on the bluff face or apparent undercutting of the bluff were also noted. Each reach was assigned a designation that best describes the vegetation line trend and erosion risk in the area with categories including: change is less than noise level, accreting, human-induced change, or erosion hazard area. In locations where erosion was detected from the imagery, a change rate averaged over approximately ten years was calculated based on the position change of the vegetation lines. Areas where signs of erosion were detected but the shoreline or vegetation line was indiscernible due to image quality or thick tree cover were also considered erosion hazard areas, and noted as a potential risk even if change rates could not be calculated. The results of the hazard assessment are available in an interactive web map which includes the designation, change rates for erosion hazard areas, and additional information that was observed from the imagery. This map is available to the public and can aid in coastal planning and risk assessments at local or regional levels.
