|
The beaches of Rich Passage are unique in their sediment characteristics, hydrodynamics, and morphologic response. Extensive physical and biological field studies were conducted in Phases 1 and 2 of this study to develop an understanding of these processes, to establish baseline conditions and to provide calibration and validation for the numerical models described in Phase 2 - Report 2. These field studies are documented in: |
|
The physical and biological data collection program includes the following: Beach profile monitoring Sediment sampling Beach observations and photography Wind, wave and current monitoring Bulkhead inventory Gravel transport studies (link) Biological studies Noise monitoring |
|
The beach response to the existing conditions in the study area is dominated by the wake climate in the summer and the wind-wave climate in the winter. An extensive wake climate analysis was undertaken to quantify and distinguish wakes produced by the various vessels that transit Rich Passage. Whereas the present wake climate is dominated by WSF car ferry wakes, POFF wakes dominated the wake climate during previous WSF Chinook-class operations, accounting for more than 50 percent of the wakes that arrived at the shoreline. In addition, the energy level of these wakes was significantly greater than either WSF car ferries or other vessels at the time. |
|
The beaches in Rich Passage fluctuate in volume from season to season. Quarterly beach profiles, ground-based photographs, and observations acquired since 2005 indicated that many sites have recovered from erosion induced by WSF POFF operations. The beaches exhibited a minor, to insignificant, response to the trial wakes of research vessel Spirit in 2005. Sediment transport processes on these beaches was investigated in this phase of the study using gravel tracers. |
|
Historically, many of the shoreline impacts from POFF operations have been related to bulkhead structures. The general condition and position of bulkheads along the shorelines of the Seattle to Bremerton ferry route were surveyed during this phase of the study to provide a baseline condition and to assess the vulnerability of structures to overtopping from wake and wind-wave events. It was found that many bulkheads within the study area were poorly designed and/or constructed. In spite of this, the majority of these structures are able to function adequately throughout most of the year and only incur minor damage during extreme winter storm events and overtopping at extreme high water levels. |
|
Biological studies were designed to characterize the nearshore habitat and biological community on the beaches along Rich Passage and to compare conditions within the study area to greater Puget Sound. A survey was conducted in summer 2006 to determine substrate composition and grain size, percent cover and abundance of macrophytes, epibenthic macro invertebrates and benthic infauna. The 2006 data collection also included reconnaissance surveys to determine the presence and extent of bull kelp on Point White and eelgrass throughout Rich Passage. In general, the biological community differed by site between January 2005 and September 2006, although the general species composition was similar among all sites. |
|
Back to Home Page |
