1 / 13

Mallard Island cross-sectional variability: low-flow, moderate-flow, and high-flow events

Mallard Island cross-sectional variability: low-flow, moderate-flow, and high-flow events. Item #2b. SF Bay Sediment Project U.S. Geological Survey Sacramento, CA. Mallard Island Cross-sectional Variability. Item #2b. Validation of sediment load calculation methodology

amity-cain
Download Presentation

Mallard Island cross-sectional variability: low-flow, moderate-flow, and high-flow events

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Mallard Island cross-sectionalvariability: low-flow, moderate-flow, and high-flow events Item #2b SF Bay Sediment ProjectU.S. Geological SurveySacramento, CA

  2. Mallard Island Cross-sectional Variability Item #2b • Validation of sediment load calculation methodology • by McKee et al. (2005) • Low-flow measurement on August 31, 2004 • Freshwater outflow at a minimum (~ 113 cms = 4,000 cfs) • Peak spring tide • Large wind-waves (>1 m) • Moderate-flow measurement on January 4, 2005 • Freshwater outflow moderate (~ 1830 cms = 64,000 cfs) • 2 days after neap tide • No wind-waves • High-flow measurement on January 5, 2006 • Freshwater outflow highest since 1997 (~ 9700 cms = 340,000 cfs) • 3 days after peak spring tide • No wind-waves

  3. Item #2b Protocol • ADCP: Perform discharge measurement, identify five discharge centroids • CTDO profiling: After ADCP measurement, return to five centroids, lower and raise CTDO package through water column at each centroid • Water sampling: Periodically collect water samples for optical sensor calibration, at multiple depths • Compare discharge-weighted SSC with SSC at gagehouse (used for McKee calculation)

  4. Item #2b

  5. Suspended-sediment record at Mallard Island Low-flow, spring tide sampling: 8/31/2004, Q = 3,892 cfs Item #2b

  6. Suspended-sediment record at Mallard Island Moderate-flow, first-flush sampling: 1/4/05, Q = 64,000 cfs Item #2b

  7. Suspended-sediment record at Mallard Island High-flow, first-flush sampling: 1/5/06, Q = 340,000 cfs Item #2b

  8. Comparison of cross-sectional, velocity-weighted SSC and Mallard Island upper SSC Item #2b Bias due to high SSC on north side of channel

  9. Item #2b Reasons to reserve judgment: NASA Pulse at Mallard Island Satellite image taken over SF Bay

  10. Item #2b Reasons to reserve judgment: NASA • NASA-ASTER image March 3, 2000, Q=150,000 cfs • Centroid of sediment pulse seaward of Suisun Bay • 17 days after peak Dayflow, 12 days after peak SSC at Mallard Island • Sediment storage in Honker Bay affecting SSC in Mallard Island X-S

  11. Item #2b Reasons to reserve judgment: models Modeled cross-sectional SSC vs. modeled upper sensor SSC

  12. Item #2b Reasons to reserve judgment: models Daily averages: modeled cross-sectional SSC vs. modeled upper sensor SSC Mean error = 25% McKee (2005) estimate = 30%

  13. Item #2b Next steps • Not enough information to definitively modify McKee’s flux estimates • Are extremes bracketed? I think so… • Need quasi-continuous velocity and SSC data over the duration of a multi-day flood event, across the channel • Two possible approaches • - Deploy multiple instrument packages in channel • - Perform a few cross-sectional surveys everyday for the duration of a 3-5 day flood pulse

More Related