Event Title

Sea Level Rise Vulnerability of San Juan County, Washington

Presentation Abstract

The objective of this study was to attain greater understanding of the areas within San Juan County that are vulnerable to implications of sea level rise. The resulting countywide mapping tool highlights areas potentially at risk to both inundation and bluff recession, for which management strategies can be developed to reduce, avert, and mitigate these SLR impacts. Inundation modeling was paired with bluff recession estimates across two SLR scenarios (moderate, high) and planning horizons (2050, 2100). Inundation mapping was conducted by linking local topography data (LIDAR) to tidal datum and elevations for each scenario and planning horizon. Inundation areas were mapped between MHHW, the highest observed water level, and each of the scenarios and planning horizons. Bluff recession estimates were developed based on a stratified sample of background erosion/change rates from different geomorphic shoretypes in the county (stratified by exposure and orientation). Change rates were measured using historic air photo analysis and digital shoreline analysis systems (DSAS). Historic recession rates were used to project future bluff recession (with accelerated recession rates based on rate of sea level rise), across the two scenarios and planning horizons. Projected bluff recession estimates were buffered from the bluff crest to map vulnerability areas. Roads and structures located within vulnerable areas were highlighted to facilitate adaptation planning. Results identified 19 miles of vulnerable roads (11.1 miles of which were county roads) and over 1,300 vulnerable structures. Together these tools can form the foundation for the development of a SLR adaptation strategy for San Juan County and increase the effectiveness of existing management approaches. In addition, these results can be used to identify additional long-term restoration and conservation targets throughout the County.

Session Title

Session S-04H: Technical Tools to Support Sea Level Rise Adaptation in the Salish Sea

Conference Track

Shorelines

Conference Name

Salish Sea Ecosystem Conference (2014 : Seattle, Wash.)

Document Type

Event

Start Date

1-5-2014 8:30 AM

End Date

1-5-2014 10:00 AM

Location

Room 607

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)

Sea levels--Washington (State)--San Juan County--Maps; Climatic changes--Washington (State)--San Juan County--Maps; Climate change mitigation--Washington (State)--San Juan County--Maps; Beach erosion--Washington (State)--San Juan County--Maps

Geographic Coverage

Salish Sea (B.C. and Wash.); San Juan County (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

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COinS
 
May 1st, 8:30 AM May 1st, 10:00 AM

Sea Level Rise Vulnerability of San Juan County, Washington

Room 607

The objective of this study was to attain greater understanding of the areas within San Juan County that are vulnerable to implications of sea level rise. The resulting countywide mapping tool highlights areas potentially at risk to both inundation and bluff recession, for which management strategies can be developed to reduce, avert, and mitigate these SLR impacts. Inundation modeling was paired with bluff recession estimates across two SLR scenarios (moderate, high) and planning horizons (2050, 2100). Inundation mapping was conducted by linking local topography data (LIDAR) to tidal datum and elevations for each scenario and planning horizon. Inundation areas were mapped between MHHW, the highest observed water level, and each of the scenarios and planning horizons. Bluff recession estimates were developed based on a stratified sample of background erosion/change rates from different geomorphic shoretypes in the county (stratified by exposure and orientation). Change rates were measured using historic air photo analysis and digital shoreline analysis systems (DSAS). Historic recession rates were used to project future bluff recession (with accelerated recession rates based on rate of sea level rise), across the two scenarios and planning horizons. Projected bluff recession estimates were buffered from the bluff crest to map vulnerability areas. Roads and structures located within vulnerable areas were highlighted to facilitate adaptation planning. Results identified 19 miles of vulnerable roads (11.1 miles of which were county roads) and over 1,300 vulnerable structures. Together these tools can form the foundation for the development of a SLR adaptation strategy for San Juan County and increase the effectiveness of existing management approaches. In addition, these results can be used to identify additional long-term restoration and conservation targets throughout the County.