Event Title

The living dike initiative

Presentation Abstract

SNC Lavalin and West Coast Environmental Law (WCEL) are leading an initiative to explore and define the implementation of a coastal flood protection system that both protects and maintains or enhances coastal and aquatic ecosystems. The purpose of the presentation is to summarize available experience and provide a preliminary technical basis to define how this objective might be realized. This “Living Dike” concept is intended as a best practice measure to meet this balanced objective and to build ongoing resilience capacity while sea levels rise in a changing climate. It is well known that coastal wetlands and marshes provide protection against storm surge and related wave effects when severe storms come ashore. Studies have also shown that salt marshes in front of coastal sea dikes can reduce the nearshore wave heights by as much as 40 percent. This reduction of the sea state in front of a dike reduces the required crest elevation and volumes of material in the dike, lowering the total cost of the dike by at least 30 percent and maximizes the time life of existing coastal structures. In most cases, existing investigations and studies consider the relative merits of wetlands and marshes for a more or less static sea level, which may include an allowance for future sea level rise. They generally do not consider the implications of the immediate loss of existing ecological services, when the future higher solution is built, or the implications of depleted ecological services, while sea levels slowly rise to reach the target elevation. The intent of the Living Dike concept is to provide a means to minimize those losses while still meeting relevant flood safety standards. The extensive engagement process being undertaken to extend benefits into coastal communities will be summarized.

Session Title

Estuarine Climate Change Adaptation

Keywords

Living dike, Salt marsh, Flooding, Sea level rise

Conference Track

SSE5: Climate Change: Impacts, Adaptation, and Research

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE5-284

Start Date

6-4-2018 11:00 AM

End Date

6-4-2018 11:15 AM

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 6th, 11:00 AM Apr 6th, 11:15 AM

The living dike initiative

SNC Lavalin and West Coast Environmental Law (WCEL) are leading an initiative to explore and define the implementation of a coastal flood protection system that both protects and maintains or enhances coastal and aquatic ecosystems. The purpose of the presentation is to summarize available experience and provide a preliminary technical basis to define how this objective might be realized. This “Living Dike” concept is intended as a best practice measure to meet this balanced objective and to build ongoing resilience capacity while sea levels rise in a changing climate. It is well known that coastal wetlands and marshes provide protection against storm surge and related wave effects when severe storms come ashore. Studies have also shown that salt marshes in front of coastal sea dikes can reduce the nearshore wave heights by as much as 40 percent. This reduction of the sea state in front of a dike reduces the required crest elevation and volumes of material in the dike, lowering the total cost of the dike by at least 30 percent and maximizes the time life of existing coastal structures. In most cases, existing investigations and studies consider the relative merits of wetlands and marshes for a more or less static sea level, which may include an allowance for future sea level rise. They generally do not consider the implications of the immediate loss of existing ecological services, when the future higher solution is built, or the implications of depleted ecological services, while sea levels slowly rise to reach the target elevation. The intent of the Living Dike concept is to provide a means to minimize those losses while still meeting relevant flood safety standards. The extensive engagement process being undertaken to extend benefits into coastal communities will be summarized.