Event Title

Tidal marsh as green infrastructure: Evaluating marsh capacity to reverse historical coastal retreat and mitigate future coastal hazards in a Salish Sea estuary

Presentation Abstract

Coastal retreat of up to 1 km since the 1960s in Port Susan Bay has led to loss of tidal marshes that historically buffered coastal overwash of important agricultural lands and dike infrastructure. The associated coastal change rates of 5.0 to 20.0 meters per year are thought to have resulted from multiple factors including emplacement of shoreline armoring that deflected fluvial sediment delivery away from the marshes. In addition, the combined influence of sea level rise and waves that resuspend and redistribute sediments may also have changed. In 2012 restoration of PSB reduced these barriers to sediment transport and research to quantify the recovery of sediment connectivity and the influence of waves today and under projected sea level rise commenced. Initial models indicate that loss of tidal marsh habitat has led to a notable loss of the ecosystem service that marsh contributes to buffering shorelines and coastal communities from wave and coastal storm surge impacts. A network of instrumentation and integrated sediment transport-wave modeling is being used to quantify the sediment budget and physical processes that influence sediment retention and marsh accretion. Using historical reconstructions of the marsh extent, we model the amount of sediment required to recover the lost marshes (green infrastructure) and associated benefit of wave attenuation. These models are run for a range of projected seal level rise and sediment delivery rates likely to be affected by changes in precipitation and runoff to evaluate the importance and value of tidal marsh as green infrastructure to protect coastal lands in Port Susan Bay and similar environments around the Salish Sea and coastal United States.

Session Title

Session S-10G: Green Infrastructure to Achieve Ecosystem Recovery Goals and Natural Hazard Mitigation

Conference Track

Shorelines

Conference Name

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

Document Type

Event

Start Date

2-5-2014 1:30 PM

End Date

2-5-2014 3:00 PM

Location

Room 6E

Contributing Repository

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

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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May 2nd, 1:30 PM May 2nd, 3:00 PM

Tidal marsh as green infrastructure: Evaluating marsh capacity to reverse historical coastal retreat and mitigate future coastal hazards in a Salish Sea estuary

Room 6E

Coastal retreat of up to 1 km since the 1960s in Port Susan Bay has led to loss of tidal marshes that historically buffered coastal overwash of important agricultural lands and dike infrastructure. The associated coastal change rates of 5.0 to 20.0 meters per year are thought to have resulted from multiple factors including emplacement of shoreline armoring that deflected fluvial sediment delivery away from the marshes. In addition, the combined influence of sea level rise and waves that resuspend and redistribute sediments may also have changed. In 2012 restoration of PSB reduced these barriers to sediment transport and research to quantify the recovery of sediment connectivity and the influence of waves today and under projected sea level rise commenced. Initial models indicate that loss of tidal marsh habitat has led to a notable loss of the ecosystem service that marsh contributes to buffering shorelines and coastal communities from wave and coastal storm surge impacts. A network of instrumentation and integrated sediment transport-wave modeling is being used to quantify the sediment budget and physical processes that influence sediment retention and marsh accretion. Using historical reconstructions of the marsh extent, we model the amount of sediment required to recover the lost marshes (green infrastructure) and associated benefit of wave attenuation. These models are run for a range of projected seal level rise and sediment delivery rates likely to be affected by changes in precipitation and runoff to evaluate the importance and value of tidal marsh as green infrastructure to protect coastal lands in Port Susan Bay and similar environments around the Salish Sea and coastal United States.