Philip Orton, Doug Wilson, David Jay, Annika Fain Oregon 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

2 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

3 Fraser River estuary, July ‘99

4 Field Measurements R/V Sproul 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

5 Anchor Station Observations, Ebb Tide

6 INVERSEINVERSE ANALYSESANALYSES Inverse Analysis Approach

7 Inverse Analysis: ABS Stage I

8 Inverse Analysis: OBS Stage I

9 Theoretical Responses

10  OBS response coeff.  : ABS response coeff. Inverse Analysis Stage II

11 Response-Modified Acoustic C at 1 m

12 Response-Modified Acoustic C at 1 m

13 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

14 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