Sediment discharge of San Lorenzo River at Big Trees (station 111605000)

Data are in tonnes Water Suspended- Bedload Total sediment year sediment discharge discharge discharge 1973 397,500 13,450 411,000 1974 84,700 10,600 95,300 1975 58,200 5,000 63,700 1976 481 94 576 WE1977 CAN DO510 BETTER7 518 1978 304,400 12,400 316,800 1979 26,200 655 26,850 1980 383,500 3,740 387,300 1981 16,900 n/a ----- Jan.4-6, 1982 853,400 3,320 856,720

ƒ From Nolan and others, 1983 Sediment-Rating Curves As Rigorous Quantitative Baselines For Evaluating Changes in Habitat-Impairing Sediment

Barry Hecht

800 Bancroft Way Berkeley, California 94710 281 Nevada Street Auburn, California 95603 224 Walnut Avenue, Suite E Santa Cruz, California 95060-3836 101 Lucas Valley Road, Suite 229 San Rafael, California 94903

10246 Donner Pass Road, Suite B3 Truckee, CA 96161 Overview

ƒ Why we need new tools of expression and analysis in fluvial-sediment transport ƒ Nature of sediment-rating curves ƒ How we can apply them Bedload and Suspended Sediment

Bedload sediment: ƒ Supported primarily by the bed ƒ Saltates and rolls ƒ Moves much more slowly than the flow ƒ Indicative of bed conditions at the time of sampling

Suspended sediment ƒ Supported mainly by turbulence of flow ƒ Moves in suspension, with the flow ƒ Indicative of sediment delivery conditions throughout the watershed Bedload sediment + Suspended sediment = Total sediment Why new tools?

ƒ Sediment is of increasing importance ƒ Habitat conditions are now often central to resource management ƒ Baselines are needed -- to establish effects or measure restoration ƒ Bedload sampling is now proven and standard (since 1980s) ƒ Sponsorship is now local or at the state scale; quicker and more informed results are needed ƒ Custom or focused inquiries can be done, because sediment sampling is increasingly by scientists or engineers, rather than by technicians ƒ We have new aquatic-habitat and geomorphic questions; focusing on sediment-transport process – and not just the yield – gives biologists new capabilities and advances habitat science. Episodic sedimentation DevilsDevils GulchGulch AlamoAlamo Channel CreekCreek incision sitessites

PilarcitosPilarcitos Geologic CreekCreek differences sitessites

Balance Hydrologics SanSan FrancisquitoFrancisquito Changes Sediment Sampling CreekCreek sitessites over time Locations in the Greater Bay Area Sediment Rating Curve Using Sediment Rating Curves for Baseline Typical Primary Episodic Events of Natural Origin Lagunitas or San Francisquito Watersheds

¾ Major storm or storms ¾ Watershed-scale wildfire ¾ Debris flow entering main channel ¾ Landslide ¾ Drought ¾ Seismic events

In many California watersheds, 30 to 50 percent of the long-term sediment yield is associated with episodic pulse-and-recovery events, commonly constituting 5 to 12 percent of the long-term record. Incorporating Episodicity Devils Gulch, Marin County Quantifying Episodic Response Devils Gulch, Marin County, CA

Watershed Sediment- Remarks condition transport relations

2.5 Normal, or Ib = 0.00061Q Minimal year-to-year variance, despite ‘chronic’ 3- and 5-year events (1978, 1980) preceding monitoring Storm

2.6 Initial recovery Ib = 0.0060Q Interpreted as removal of sediment stored on bed and sub-0.5 bankfull channel, based on field observations 3.6 Late-stage Ib = 0.000015Q Depletion of high-bank storage recovery Normal, or Resumed pre- Followed by very wet year, so other ‘chronic’ event relations late-stage relations obscured. Effects of Incision

• West Alamo and Alamo Creeks, Contra Costa County, California

Effects of channel incision on equations of the sediment rating curves Effects of Rock Type Pilarcitos Watershed and Vicinity

• Franciscan • Hard sandstones • Weather granitics 10000Corinda Los Trancos Cr. at Highway 92 (incising granitics)

Apanolio Cr. at Highway 92 (weathered granitics)

Corte Madera Cr. at Westridge Drive (softer sandstones and shales) 1000 Los Trancos Cr. above Arastradero (lithified sandstones and shales)

Mills Cr. at Higgins Road (lithified sandstones and shales)

100Devils Gulch at Sir Francis Drake Blvd.: chronic condition (Franciscan)

Devils Gulch at Sir Francis Drake Blvd.: episodic condition Influence of (Franciscan) 10 Bedrock Geology 1 Sediment Discharge (tons/day) Discharge Sediment

0.1

0.01 0.1 1 10 100 1000 Instantaneous Stream Flow (cfs)

Effects of geology: comparison of bedload- sediment discharge in the Pilarcitos Creek watershed to other Bay Area streams, water year 2000. Discussion

In recent years, use of informed sediment-rating curves has been increasingly: ƒ Needed, given new habitat and alluvial-corridor priorities ƒ Needed, given new habitat and alluvial- corridor priorities ƒ Useful, given the growing number of curves available ƒ Needed, given new habitat and alluvial- corridor priorities ƒ Useful, given the growing number of curves available ƒ Important, given the need for short- term baselines or immediate answers to management issues ƒ Needed, given new habitat and alluvial- corridor priorities ƒ Useful, given the growing number of curves available ƒ Important, given the need for short-term baselines or immediate answers to management issues ƒ Responsive, given shifts toward state and local support or funding ƒ Needed, given new habitat and alluvial- corridor priorities ƒ Useful, given the growing number of curves available ƒ Important, given the need for short-term baselines or immediate answers to management issues ƒ Responsive, given shifts toward state and local support or funding, and ƒ Timely, given increasing proportion of data collection by experienced scientists with multiple questions. Thinking Like A Geographer

1. Identify processes: What is going on? Is this the whole picture?

2. Identify the full nature of the event or condition

3. How can this work be applied regionally? (Regional allegiance)

4. How can this work be applied culturally?

5. How can I learn from cultural wisdom, and add to it? Recap

To effectively manage, we need more than a sediment yield Recap (cont’d)

Sediment transport can be presented as sediment-rating curves, for both bedload and suspended sediment, which have multiple, critically-needed applications in identifying sediment dynamics. Recap (cont)

By illustrating . . .

ƒ Pre- and post-project changes ƒ Episodic changes in supply and transport ƒ Effects of incision ƒ Differing responses in varying soil and bedrock types

. . . sediment-rating curves can help distinguish responses, transfer learned lessons, and guide an (immigrant) culture toward sounder management.

This is work that bridges the boundaries between biology and hydrology in a way that allows us to understand change over time (1-20 years) and space (from one subwatershed to another), offering the promise of long-term site-specific solutions that lead to sustainable habitat management. Questions? Lagunitas Regional Professional vs. Technical/Specialist-based data collection Scientists/Engineers

ƒ Generally conducting sediment -source, or -effects studies in the same watershed

ƒ Often familiar with the whole watershed

ƒ Can apply results to multiple issues and in multiple venues

ƒ Data collection more site- or condition-specific Technician/Specialists

ƒ Data collection and preservation is more uniform

ƒ Higher level of quality-control

ƒ Often more data on site conditions at time of sampling

Applications ƒ TMDL or load-based regulations

ƒ Navigation or sedimentation management

ƒ Gravel recruitment

ƒ Early warning of bed-habitat improvement or deterioration

ƒ Validation of sampling Table 1. Sediment rating-curve equations for San Francisco Bay Area Creeks

Vaild Suspended-sediment Vaild Range of Bedload-sediment Water Year Range of Source of Data Stream Station curve Flow curve

d Area Flow Watershe (square miles) (tons/day) (cfs) (tons/day) (cfs)

2.63 Devils Gulch at 2.7 1982 chronic sediment conditions 0.000428*Q all ranges Barry Hecht 2.531 Sir Francis Drake Blvd. 1982 episodic sediment conditions 0.006058*Q all ranges Barry Hecht

2.5 Wildcat Creek 7.78 1978-1980 0.01*Q all ranges data by USGS 2.5 3.18 7.78 2004-2006 0.005*Q all ranges 0.000009*Q all ranges Balance Hydrologics, Inc

1.81 Cull Creek 5.79 1981 to 1984 0.75*Q all ranges USDA, 1987

2.01 San Lorenzo Creek 18.00 1981 to 1984 0.1*Q all ranges USDA, 1987

2.140 Alamo Creek, main branch 1998 to 1999 0.0938*Q all ranges Balance Hydrologics, Inc

Coming to www.balancehydro.com soon! 90 8000 Annual average flow Annual peak flow 80 7000

70 6000

60 5000

50 4000 40

Annual Average Flow (cfs) Flow Average Annual 3000

30 Annual Peak Flow (cfs)

2000 20

1000

10 1942-1950 gaged not San Francisquito Creek Francisquito San

0 0 1932 1934 1936 1938 1940 1942 1944 1946 1948 1950 1952 1954 1956 1958 1960 1962 1964 1966 1968 1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 Water Year Figure __. Annual average flow and annual peak flow history: San Francisquito Creek at Stanford Golf Course. This illustrates total runoff for a year as well as the intensity of the largest storm. 25

20 year)

15

10 Annual deposition rate (ac-ft/ rate deposition Annual

5

0 1892 to 1913 1913 to 1929 1929 to 1946 1946 to 1995 1996 to 2000

Searsville Lake annual deposition rates calculated by sequential bathymetric surveys. Volumes of deposition calculated include only deposition below lake level, and exclude deposition in the alluvial margins of the lake; total deposition rates would be significantly higher for the period 1996 through 2000 if margins are included.