Type of Presentation

Oral

Session Title

Long term studies reveal the complex dynamics and interconnectivity of the physical, geomorphic, biological systems of Salish Sea shorelines and how these systems interact with social and political systems

Description

Annual and seasonal patterns of sediment transport and morphologic response are examined for a mixed sand and gravel beach in Rich Passage, Puget Sound, WA exposed to wind waves, vessel wakes, and tidal currents. Gravel transport was measured in three intervals at two sites on Point White, Bainbridge Island, WA using Radio Frequency Identification (RFID) Passive Integrated Transponder (PIT) technology and high resolution laser scanning topographic surveys. The measurements are used to examine the relative influence of mechanisms forcing alongshore and cross-shore transport at the two sites, to characterize seasonal and annual sediment transport rates and compare and contrast transport and morphology change patterns under different vessel operating regimes. During the first interval (2006 to 2007) alongshore transport dominated as a result of wind-wave forcing during the storm intervals (winter condition); cross-shore transport resulted primarily from car ferry wake wash and tidal forcing during non-storm intervals (summer condition) (Curtiss et al. 2009). During the second interval (summer of 2012) a new high speed, low wake ferry, Rich Passage 1 (RP1), was tested in-situ for a 6-month interval (Cote et al, 2013). The third interval (2013-2015) encompasses ongoing beach response monitoring after the completion of in-situ testing of RP1.

Alongshore transport rates during the RP1 test interval were larger at both sites compared to similar non-storm intervals in 2006 and 2007, but were lower than rates observed during storm intervals in 2006 and 2013. Transport rates during the non-storm interval in 2013 were similar to baseline rates of transport (2006-2007). Difference maps of beach elevation show cross-shore gravel bar formation and alongshore patterns of northeast oriented shore-oblique gravel bedforms.

The almost ten years of measurements have been essential for comparing the beach response observed during the RP1 test interval in relation to seasonal and inter-annual beach response.

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Patterns of sediment transport and morphologic response on a mixed sand and gravel beach in Rich Passage, Puget Sound

2016SSEC

Annual and seasonal patterns of sediment transport and morphologic response are examined for a mixed sand and gravel beach in Rich Passage, Puget Sound, WA exposed to wind waves, vessel wakes, and tidal currents. Gravel transport was measured in three intervals at two sites on Point White, Bainbridge Island, WA using Radio Frequency Identification (RFID) Passive Integrated Transponder (PIT) technology and high resolution laser scanning topographic surveys. The measurements are used to examine the relative influence of mechanisms forcing alongshore and cross-shore transport at the two sites, to characterize seasonal and annual sediment transport rates and compare and contrast transport and morphology change patterns under different vessel operating regimes. During the first interval (2006 to 2007) alongshore transport dominated as a result of wind-wave forcing during the storm intervals (winter condition); cross-shore transport resulted primarily from car ferry wake wash and tidal forcing during non-storm intervals (summer condition) (Curtiss et al. 2009). During the second interval (summer of 2012) a new high speed, low wake ferry, Rich Passage 1 (RP1), was tested in-situ for a 6-month interval (Cote et al, 2013). The third interval (2013-2015) encompasses ongoing beach response monitoring after the completion of in-situ testing of RP1.

Alongshore transport rates during the RP1 test interval were larger at both sites compared to similar non-storm intervals in 2006 and 2007, but were lower than rates observed during storm intervals in 2006 and 2013. Transport rates during the non-storm interval in 2013 were similar to baseline rates of transport (2006-2007). Difference maps of beach elevation show cross-shore gravel bar formation and alongshore patterns of northeast oriented shore-oblique gravel bedforms.

The almost ten years of measurements have been essential for comparing the beach response observed during the RP1 test interval in relation to seasonal and inter-annual beach response.