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April 4, 2008 Variation in salmonid bed-habitat conditions with sediment yields in Lagunitas and San Geronimo Creeks Marin County, California Barry Hecht,

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Presentation on theme: "April 4, 2008 Variation in salmonid bed-habitat conditions with sediment yields in Lagunitas and San Geronimo Creeks Marin County, California Barry Hecht,"— Presentation transcript:

1 April 4, 2008 Variation in salmonid bed-habitat conditions with sediment yields in Lagunitas and San Geronimo Creeks Marin County, California Barry 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 Road Occidental, California, 95465

2 Overview Study area and background Hydrology during the monitoring period The Thesis The Approach Findings

3 Location Bed monitoring sites

4 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 – Kelleys Upper State Park Bed monitoring sites

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7 Watershed Hydrology Peak Discharge, 1980 to 2007

8 Watershed Hydrology

9 Main Monitoring Program Elements Studies 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)

10 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.

11 Methodology Bed Census 1. 1. Establish reach morphology (Geomorphic reconnaissance)

12 Methodology Bed Census 1. 1. Establish reach morphology Segment

13 Methodology Bed Census 1. 1. Establish reach morphology Segment Sequence

14 Methodology Bed Census 1. 1. Establish reach morphology Sequence Site Segment

15 Methodology Bed Census 1. 1. Establish reach morphology 2. 2. Modified Wolman Pebble count 3. 3. Visual estimate of embeddedness 4. 4. Bed core

16 Methodology Bed Census 1. 1. Establish reach morphology 2. 2. Modified Wolman Pebble count 3. 3. Visual estimate of embeddedness 4. 4. Bed core 5. 5. Annual cross-section surveys

17 Methodology Sediment Transport Instantaneous bedload sediment measurements Instantaneous suspended sediment measurements Continuous streamflow gaging

18 2002-2003 pulse and hydrologic context

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20 2002-2003 pulse: sediment transport rates

21 The Gestalt How is the 2002 sediment pulse reflected by changes in bed conditions?

22 2002-2003 pulse: mean bed elevation KB – Below Shafter - Pool Increase in sand, cobble, organics

23 2002-2003 pulse: bed cover KH – Kelleys Upper - Pool Increase in sand Decrease in cobbles, bedrock

24 2002-2003 pulse: embeddedness KH – Kellys Upper - Pool Slight increase in embeddedness, followed by mild recovery

25 2002-2003 pulse: mean bed elevation KH – Kelleys Upper State Park Slowed rate of incision

26 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

27 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.

28 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.

29 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.

30 Conclusion The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.

31 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:

32 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,

33 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

34 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)

35 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:

36 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,

37 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

38 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

39 Questions?


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