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April 4, 2008
Variation in salmonid bed-habitat conditions with sediment yields in
Lagunitas and San Geronimo Creeks
Marin County, CaliforniaBarry Hecht, David Shaw, Jonathan Owens, Mark Woyshner
Balance Hydrologics, Inc.800 Bancroft Way, Suite 101, Berkeley, California, 94710
PO Box 1077, Truckee, California, 94160(510) 704-1000
dshaw@balancehydro.com
and
Eric Austensen Streamline Engineering
2727 Marra RoadOccidental, California, 95465
Overview
Study area and backgroundHydrology during the monitoring
periodThe ThesisThe ApproachFindings
Location
Bed monitoring sites
Location
Balance Hydrologics K4 – San Geronimo Creek Stream Gage
USGS 11460400 and Balance Hydrologics KC
– Lagunitas Creek at
Samual P. Taylor State Park Stream Gage
KB – Below Shafter Bridge
KH – Kelley’s Upper State
Park
Bed monitoring sites
Watershed HydrologyPeak Discharge, 1980 to 2007
Watershed Hydrology
Main Monitoring Program ElementsStudies began in 1979 as a condition of the EIR on raising Peters Dam to increase
storage in Kent Lake
Geomorphic reconnaissance and bed conditions (Balance Hydrologics; Streamline, 1979-present)
Stream and sediment gaging(Balance Hydrologics, 1979-present)
Fisheries investigations and monitoring(various consultants; MMWD; RWQCB staff, 1976-present)
Scour chain studies in spawning areas (Balance Hydrologics, 2002-2006)
The Gestalt
Bed condition surveys and sediment transport data provide information about immediate and long-term changes in watershed and bed habitat conditions.
Relating the two means that bed sedimentation – or improvements in bed conditions – can be monitored more effectively and frequently.
MethodologyBed Census
1. Establish reach morphology(Geomorphic
reconnaissance)
MethodologyBed Census
1. Establish reach morphology
Segment
MethodologyBed Census
1. Establish reach morphology
Segment
Sequence
MethodologyBed Census
1. Establish reach morphology
Sequence
Site
Segment
MethodologyBed Census
1. Establish reach morphology
2. Modified Wolman Pebble count
3. Visual estimate of embeddedness
4. Bed core
MethodologyBed Census
1. Establish reach morphology
2. Modified Wolman Pebble count
3. Visual estimate of embeddedness
4. Bed core5. Annual cross-section
surveys
MethodologySediment Transport
Instantaneous bedload sediment measurements
Instantaneous suspended sediment measurements
Continuous streamflow gaging
2002-2003 pulse and hydrologic context
2002-2003 pulse and hydrologic context
2002-2003 pulse: sediment transport rates
The Gestalt
How is the 2002 sediment pulse reflected by changes in bed conditions?
2002-2003 pulse: mean bed elevation
KB – Below Shafter - Pool
Increase in sand, cobble, organics
2002-2003 pulse: bed cover
KH – Kelley’s Upper - Pool
Increase in sandDecrease in cobbles, bedrock
2002-2003 pulse: embeddedness
KH – Kelly’s Upper - Pool
Slight increase in embeddedness, followed by mild recovery
2002-2003 pulse: mean bed elevation
KH – Kelley’s Upper State Park
Slowed rate of incision
Conclusion Bedload delivery rates and changes in bed conditions are closely
related, as observed during a 2002-3 sediment pulse and recovery along Lagunitas Creek during a series of years with only moderate flows
Conclusion Bedload delivery rates and changes in bed conditions are closely
related, as observed during a 2002-3 sediment pulse and recovery along Lagunitas Creek
The most direct response was measured as changes in the percent of bed area covered with fines (<4 mm) and cobbles.
Conclusion Bedload delivery rates and changes in bed conditions are closely
related, as observed during a 2002-3 sediment pulse and recovery along Lagunitas Creek
The most direct response was measured as changes in the percent of bed area covered with fines (<4 mm) and cobbles.
Embeddedness is less responsive to changes in sediment transport.
Conclusion Bedload delivery rates and changes in bed conditions are closely
related, as observed during a 2002-3 sediment pulse and recovery along Lagunitas Creek
The most direct response was measured as changes in the percent of bed area covered with fines (<4 mm) and cobbles.
Embeddedness is less responsive to changes in sediment transport.
Both bed-condition monitoring or bedload transport monitoring can tell us whether sediment loads are likely to be affecting habitat values.
Conclusion
The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.
Conclusion
The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.
Bedload transport gaging is generally favored if:
Conclusion
The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.
Bedload transport gaging is generally favored if: Sediment-rating curves have been established,
Conclusion
The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.
Bedload transport gaging is generally favored if: Sediment-rating curves have been established, Intra-season or multi-year variability must be tracked, and/or
Conclusion
The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.
Bedload transport gaging is generally favored if: Sediment-rating curves have been established, Intra-season or multi-year variability must be tracked, and/or Where management depends upon clear demonstration of the
sediment source (gage location is key)
Conclusion
The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.
Bedload transport gaging is generally favored if: Sediment-rating curves have been established, Intra-season or multi-year variability must be tracked, and/or Where management depends upon clear demonstration of the
sediment source, among other considerations. Bed-condition monitoring is advantageous when:
Conclusion
The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.
Bedload transport gaging is generally favored if: Sediment-rating curves have been established, Intra-season or multi-year variability must be tracked, and/or Where management depends upon clear demonstration of the
sediment source, among other considerations. Bed-condition monitoring is advantageous when:
Only once-a-year or less frequent monitoring is required or feasible,
Conclusion
The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.
Bedload transport gaging is generally favored if: Sediment-rating curves have been established, Intra-season or multi-year variability must be tracked, and/or Where management depends upon clear demonstration of the
sediment source, among other considerations. Bed-condition monitoring is advantageous when:
Only once-a-year or less frequent monitoring is required or feasible, Minimal migration or downstream mobility of bed segments, and/or
Conclusion
The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.
Bedload transport gaging is generally favored if: Sediment-rating curves have been established, Intra-season or multi-year variability must be tracked, and/or Where management depends upon clear demonstration of the
sediment source Bed-condition monitoring is advantageous when:
Only once-a-year or less frequent monitoring is required or feasible, Minimal migration or downstream mobility of bed segments, and/or Volunteers are available
Questions?
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