Modeling the regional wave climate of northern Puget Sound across the Strait of Juan de Fuca and Whidbey Basin using the open-source hydrodynamic software Delft3D. The objective is to assess changes in wave energy and impacts to substrates, habitats and infrastructure along shorelines with regional projections of sea-level rise, winds and atmospheric pressure patterns. Expected outputs including a modeling tool for broad community use, modeled and mapped GIS layers of projected wave heights, inundation patterns and impacts, and relative vulnerability indices intend to inform decision makers with important tools to guide climate change adaptation.

For more information, please contact Eric Grossman

This study is developing quantitative metrics of the structural properties of dominant salt marsh species to include in hydrodynamic models. One objective is to develop “rapid assessment protocols” (RAPs) to map vegetation distribution, biomass, plant metrics (shoot density, shoot length/width) and structural properties (rigidity/elasticity) using new side-on photography and digital image analyses techniques and remote sensing. A second objective is to assess the extent that salt marsh habitat attenuates wave energy and sediment through modeling the transformation of waves as they reach shore and measurements of waves to validate the models. Port Susan Bay was selected to address nearly 1-km of marsh retreat since the 1960s that is suspected to have led to greater inundation during coastal storm surges and to inform the performance of the 2012 PSB estuary restoration led by The Nature Conservancy.

For more information, please contact Eric Grossman

The significant rerouting of ~70% of the N Fork Skagit River flow and sediment through a new distributary channel provides insight to (1) the instability and hazards of the river due to excess sedimentation and (2) extensive impacts to important salmon rearing habitats (tidal marsh, marsh channels, eelgrass) and food-resources. The team is studying the rates of bedload movement and delta fan progradation through the new “avulsion” channel and out across the tidal flats, which range 1-2 m per day and the impacts the sediment is having on eelgrass habitats and benthic invertebrate biomass and diversity. This research helps to quantify the affects that sediment re-routing has on downstream (nearshore) habitats important to salmon recovery and informs decision makers of the need to more strategically sequence restoration across floodplains and estuaries in order to achieve mutual benefits for flood reduction (reduce sedimentation in the lower rivers and estuary channels that cause grater flood risk) and salmon recovery (reduce impacts to eelgrass while ensuring sediment transport to ailing tidal marshes vulnerable to sea-level rise.

For more information, please contact Eric Grossman