Presentation Abstract

Beaches constitute more than 50% of Puget Sound’s 4000 km shoreline. More than a quarter are armored or buried under fill and many others have been impacted indirectly by changes to adjacent shorelines and to sediment transport regimes. Restoring these beaches typically involves removing bulkheads and groins, excavating historic fill, replacing lost sediment, and replumbing tidal inlets and stream mouths. We often emphasize process-based restoration, but for beaches, what does this mean? Geomorphic processes operating on beaches include erosion, deposition, overwash, sediment supply and transport, stream flow, and shoreline migration. These physical processes in turn impact ecosystems by shaping the distribution of habitats and dictating disturbance patterns. Process-based restoration means allowing sediment to move, flooding to occur, and landforms to migrate, all of which can impact existing ecosystems and threaten the human landscape, adding significantly to project complexity and risk. Successful restoration requires understanding basic beach behavior, but it also involves awareness of the different spatial and temporal scales at which processes occur and recognizing that beach systems are inherently dynamic. Ultimately, we recognize that the goal should be to restore processes, not to create static landscapes, something that will become increasingly relevant in an era of rapidly rising sea levels. We will look at beach projects from around the Salish Sea and examine geomorphic factors that influence their performance. While some of these are fairly site-specific design issues, others are related to the complex challenges of restoring dynamic features in landscapes that continue to evolve over time. The lessons inform not only how we build projects, but what we monitor and how we define restoration in 21st century coastal systems.

Session Title

Challenges and Solutions for Shoreline Armor Removal and Design of Soft Shore Protection: Part I

Keywords

Restoration, Puget Sound Beach

Conference Track

SSE1: Habitat Restoration and Protection

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE1-314

Start Date

4-4-2018 1:45 PM

End Date

4-4-2018 2:00 PM

Type of Presentation

Oral

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and 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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Apr 4th, 1:45 PM Apr 4th, 2:00 PM

Geomorphic challenges to restoring Puget Sound beaches

Beaches constitute more than 50% of Puget Sound’s 4000 km shoreline. More than a quarter are armored or buried under fill and many others have been impacted indirectly by changes to adjacent shorelines and to sediment transport regimes. Restoring these beaches typically involves removing bulkheads and groins, excavating historic fill, replacing lost sediment, and replumbing tidal inlets and stream mouths. We often emphasize process-based restoration, but for beaches, what does this mean? Geomorphic processes operating on beaches include erosion, deposition, overwash, sediment supply and transport, stream flow, and shoreline migration. These physical processes in turn impact ecosystems by shaping the distribution of habitats and dictating disturbance patterns. Process-based restoration means allowing sediment to move, flooding to occur, and landforms to migrate, all of which can impact existing ecosystems and threaten the human landscape, adding significantly to project complexity and risk. Successful restoration requires understanding basic beach behavior, but it also involves awareness of the different spatial and temporal scales at which processes occur and recognizing that beach systems are inherently dynamic. Ultimately, we recognize that the goal should be to restore processes, not to create static landscapes, something that will become increasingly relevant in an era of rapidly rising sea levels. We will look at beach projects from around the Salish Sea and examine geomorphic factors that influence their performance. While some of these are fairly site-specific design issues, others are related to the complex challenges of restoring dynamic features in landscapes that continue to evolve over time. The lessons inform not only how we build projects, but what we monitor and how we define restoration in 21st century coastal systems.