Proposed Abstract Title

South and Central Puget Sound Flushing Times and Residual Flows

Type of Presentation

Oral

Session Title

General oceanography

Location

2016SSEC

Description

South and Central Puget Sound is a part of the Salish Sea extending south of Edmonds to Oakland Bay in Shelton, Washington. Flushing times for several inlets including Henderson, Budd, Eld, Totten, and Oakland Bay were studied as well as residual flows at several locations. Flushing strongly influences water quality and biological processes. Areas with low flushing time can be sensitive to even small inputs whereas areas with strong flushing can buffer the influences of external inputs.

The flushing times for each of the inlets can be based upon exchanges at the mouth of each inlet (each inlet dyed individually) or based upon exchanges at Tacoma Narrows (when the whole South Puget Sound domain is dyed), or based upon exchanges at Edmonds (when the whole model domain is dyed). While the first approach shows how much of riverine flows and near inlet waters help flush a specific inlet the latter scenarios includes the effects of flushing by water external to Tacoma Narrows or Edmonds.

Flushing time varies seasonally due to changing freshwater contributions that affect net transport and changing tidal prisms. Dye-based flushing time calculations rely on dilution with both riverine and sub tidal flows. Boundary location and conditions are important in estimating flushing times. A calibrated three dimension model was used to simulated dye release. The e-folding time or residence time for South Puget Sound was estimated at 76.5 days. This is higher than the flushing time (46.1 days) estimated previously using a two layer box model

Seaward and landward components of residual flows for each cell and each layer were evaluated. Residual flows at seven different transects were compared with literature. Results provide important physical context for different regions of South and Central Puget Sound. Each inlet functions differently in part due to differences in flushing time.

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South and Central Puget Sound Flushing Times and Residual Flows

2016SSEC

South and Central Puget Sound is a part of the Salish Sea extending south of Edmonds to Oakland Bay in Shelton, Washington. Flushing times for several inlets including Henderson, Budd, Eld, Totten, and Oakland Bay were studied as well as residual flows at several locations. Flushing strongly influences water quality and biological processes. Areas with low flushing time can be sensitive to even small inputs whereas areas with strong flushing can buffer the influences of external inputs.

The flushing times for each of the inlets can be based upon exchanges at the mouth of each inlet (each inlet dyed individually) or based upon exchanges at Tacoma Narrows (when the whole South Puget Sound domain is dyed), or based upon exchanges at Edmonds (when the whole model domain is dyed). While the first approach shows how much of riverine flows and near inlet waters help flush a specific inlet the latter scenarios includes the effects of flushing by water external to Tacoma Narrows or Edmonds.

Flushing time varies seasonally due to changing freshwater contributions that affect net transport and changing tidal prisms. Dye-based flushing time calculations rely on dilution with both riverine and sub tidal flows. Boundary location and conditions are important in estimating flushing times. A calibrated three dimension model was used to simulated dye release. The e-folding time or residence time for South Puget Sound was estimated at 76.5 days. This is higher than the flushing time (46.1 days) estimated previously using a two layer box model

Seaward and landward components of residual flows for each cell and each layer were evaluated. Residual flows at seven different transects were compared with literature. Results provide important physical context for different regions of South and Central Puget Sound. Each inlet functions differently in part due to differences in flushing time.