Philip Orton, Doug Wilson, David Jay, Annika FainOregon Graduate Institute, Environmental Science & Engineering

Funded by The National Science Foundation LMER project

Sediment analyses by Denise Reed at U. New Orleans

High-resolution sediment dynamics in a salt-wedge

estuary

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Summary

• Inverse analysis: optical and acoustical SPM

• Several advantages– detection of wide range of sediment sizes– concentrations by settling velocity (Ws) classes– high-resolution compared to tidal timescales

• Fraser River estuary - erosion thresholds, resuspension mechanisms

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Fraser River estuary, July ‘99

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Field Measurements

• R/V Sproul - 1999 anchor stations

– ABS: 300 kHz BB-ADCP, t=20 sec

– OBS: CTD-OBS profiles, t=30 min

– Concentration (C), t=2 hrs

– Settling rate (Ws), t=2 hrs

– Zooplankton, primary productivity, etc

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Anchor Station Observations, Ebb Tide

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INVERSE

ANALYSES

Inverse Analysis Approach

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Inverse Analysis: ABS Stage I

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Inverse Analysis: OBS Stage I

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Theoretical Responses

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OBS response coeff. : ABS response coeff.

Inverse Analysis Stage II

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Response-Modified Acoustic C at 1 m

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Response-Modified Acoustic C at 1 m

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Future Analyses

• Wealth of data from the Columbia River estuary and the Fraser River estuary

• Multi-frequency acoustics

• For 2000, LISST particle size observations

• Modify approach to include advection

• Sensitivity analyses are critical

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Fraser 1999 Conclusions

• Joint acoustic/optic approach invaluable due to wide range of sediment types

• IA allows us to... – study sediment erosion, transport by Ws-class– achieve resolution not available with

conventional sediment monitoring tools