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San Joaquin River Bedload Sampling summary. January 4 and 5, 2011 April 1 and 2, 2011 Ledger Island. Purpose of Bedload Sampling at Ledger Island. Contribute to understanding mobility thresholds of different grain sizes ( sand gravel )
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San Joaquin River Bedload Sampling summary January 4 and 5, 2011 April 1 and 2, 2011 Ledger Island
Purpose of Bedload Sampling at Ledger Island • Contribute to understanding mobility thresholds of different grain sizes (sandgravel) • Estimate sand transport rates in Reach 1A to evaluate fine sediment budget, will inform future fine sediment management for spawning and rearing habitat • Estimate coarse sediment transport rates in Reach 1A to inform future spawning gravel augmentation needs
January 4-5 and April 1-2 Friant Dam Flood Control Releases 8,060 cfs 8,090 cfs 4,690 cfs 7,000 cfs
Sample Processing • Bedload discharge < 2mm • Bedload discharge <8mm • Bedload discharge between 2mm and 8mm • Bedload discharge >8mm • Total bedload discharge
Sample Analysis • 4 passes at 4,690 cfs • 1 pass at 5,200 cfs • 1 pass at 5,800 cfs • 4 passes at 7,000 cfs • 5 passes at 8,090 cfs • 5 passes at 8,060 cfs • 4 passes at 4,000 cfs and 6,000 cfs averaged into two samples • 5 passes at 8,090 cfs and 8,060 cfs averaged into two samples
Bedload Transport Data >2mm Largest grain in transport =115 mm at 8,060 cfs
Next Steps • Prepare short tech memo summarizing methods and results • Send bedload data to SJRRP (Erin?) for distribution to Program technical staff and consultants • Technical discussion of additional sampling needs • Sampling location • Target flows • Considerations for RA/TAC Recommendations