Presentation Abstract

The Puget Sound is a complex estuarine system within the Salish Sea, fed by both high salinity water from the Pacific Ocean and freshwater from a number of rivers. The Snohomish River is one of the largest of these inputs, transporting freshwater from the Skykomish and Snoqualmie rivers to Port Gardner Bay off the coast of Everett. At its mouth, the higher density salt water from the Puget Sound intrudes into the freshwater, forming a salt wedge that causes a highly stratified water column which rapidly changes with the tidal cycle. In this highly stratified water column, little mixing occurs between the different layers of the water, resulting in a lack of nutrients near the surface. This study aims to quantify the amount of mixing occurring at this location in relation to tidal patterns and season, and analyze the effect varying levels of mixing have on related chemical properties. This research is being conducted at the Ocean Research College Academy (ORCA), a dual enrollment program through Everett Community College. In cooperation with Gravity Marine Consulting and the Port of Everett, ORCA has moored a SeaBird CTD two meters below the surface and a Nortek Aquadopp Profiler (ADCP) on the seafloor of the Snohomish River. The CTD captures temperature, salinity, chlorophyll, turbidity, and dissolved oxygen measurements at 30-minute intervals. The ADCP measures current speed, direction, and velocity in three dimensions through sound wave scattering. In addition, a chain of DS18B20 temperature sensors has been deployed at .3 meter increments to a depth of two meters in order to profile temperature gradients in the water column. This study will quantitatively define water column mixing in terms of vertical current velocity and sediment concentrations. Various chemical properties will then be correlated with this mixing, providing an overarching view of the water column.

Session Title

Posters: Data & Information Management

Keywords

ADCP, Mixing, Salt Wedge, Turbulence, Tidal Forcing, Snohomish River

Conference Track

SSE18: Posters

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE18-28

Start Date

5-4-2018 11:30 AM

End Date

5-4-2018 1:30 PM

Type of Presentation

Poster

Contributing Repository

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

Geographic Coverage

Salish Sea (B.C. and Wash.)

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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Apr 5th, 11:30 AM Apr 5th, 1:30 PM

The impact of water column mixing in a salt wedge estuary

The Puget Sound is a complex estuarine system within the Salish Sea, fed by both high salinity water from the Pacific Ocean and freshwater from a number of rivers. The Snohomish River is one of the largest of these inputs, transporting freshwater from the Skykomish and Snoqualmie rivers to Port Gardner Bay off the coast of Everett. At its mouth, the higher density salt water from the Puget Sound intrudes into the freshwater, forming a salt wedge that causes a highly stratified water column which rapidly changes with the tidal cycle. In this highly stratified water column, little mixing occurs between the different layers of the water, resulting in a lack of nutrients near the surface. This study aims to quantify the amount of mixing occurring at this location in relation to tidal patterns and season, and analyze the effect varying levels of mixing have on related chemical properties. This research is being conducted at the Ocean Research College Academy (ORCA), a dual enrollment program through Everett Community College. In cooperation with Gravity Marine Consulting and the Port of Everett, ORCA has moored a SeaBird CTD two meters below the surface and a Nortek Aquadopp Profiler (ADCP) on the seafloor of the Snohomish River. The CTD captures temperature, salinity, chlorophyll, turbidity, and dissolved oxygen measurements at 30-minute intervals. The ADCP measures current speed, direction, and velocity in three dimensions through sound wave scattering. In addition, a chain of DS18B20 temperature sensors has been deployed at .3 meter increments to a depth of two meters in order to profile temperature gradients in the water column. This study will quantitatively define water column mixing in terms of vertical current velocity and sediment concentrations. Various chemical properties will then be correlated with this mixing, providing an overarching view of the water column.