U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2007–5254

Sources, Dispersal, and Fate of Fine Sediment Supplied to 

Coastal California
COVER

Turbid sediment plumes along the California coast near Gaviota following storms of February 1998. Picture 

by Mark Defeo and used by permission.
Sources, Dispersal, and Fate of Fine 

Sediment Supplied to Coastal California

By Katherine L. Farnsworth and Jonathan A. Warrick

Scientific Investigations Report 2007–5254

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

For product and ordering information:

World Wide Web: http://www.usgs.gov/pubprod

Telephone: 1-888-ASK-USGS

For more information on the USGS--the Federal source for science about the Earth, its natural and living resources, 

natural hazards, and the environment:

World Wide Web: http://www.usgs.gov

Telephone: 1-888-ASK-USGS

Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Farnsworth, K.L., Warrick, J.A., 2007, Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California: 

U.S. Geological Survey Scientific Investigations Report 2007–5254, 77 p.
iii

Contents

Executive Summary.......................................................................................................................................1

Introduction.....................................................................................................................................................2

What Is Fine Sediment?................................................................................................................................2

Sources of Fine Sediment.............................................................................................................................3

Fluvial Sources......................................................................................................................................3

Rating Curves................................................................................................................................3

Fine-Sediment Fraction...............................................................................................................5

Error Calculations ........................................................................................................................6

Original Measurement and Reporting.............................................................................6

Sediment-Discharge Rating Curve ..................................................................................6

Extrapolation of Loess Rating Curve................................................................................6

Fine-Sediment-Fraction/Discharge Relation..................................................................7

Extrapolation of Fine-Sediment-Fraction/Discharge Relation ....................................7

Calculation of Sediment Load....................................................................................................7

Extrapolation to Unmonitored Watersheds .............................................................................7

River-Sediment Discharge .........................................................................................................8

Cliff and Bluff Sources .......................................................................................................................12

Summary...............................................................................................................................................14

Dispersal of Fine Sediment.........................................................................................................................16

Introduction..........................................................................................................................................16

Previous Investigations......................................................................................................................16

Research Questions ...........................................................................................................................20

Techniques...........................................................................................................................................20

Results. ..................................................................................................................................................21

Eel River.......................................................................................................................................21

Salinas River...............................................................................................................................21

Santa Clara River.......................................................................................................................26

Summary...............................................................................................................................................26

Fate and Accumulation of Fine Sediment................................................................................................26

Introduction..........................................................................................................................................26

Techniques...........................................................................................................................................29

Grain Size on the California Continental Shelf...............................................................................31

Fine-Sediment-Accumulation Rates................................................................................................31

Summary...............................................................................................................................................37

Conclusions...................................................................................................................................................37

Acknowledgments.......................................................................................................................................37

References Cited..........................................................................................................................................37

Appendix A. Grain-Size Information .........................................................................................................42

Appendix B. Sediment-Discharge Rating Curves for All Stations .......................................................43

Appendix C. Fine-Sediment-Fraction/Discharge Curves for All Stations...........................................70

Appendix D. Fine-Sediment Contributions to Coastal California from Coastal Cliffs and Bluffs ....76
iv

Figures

1. Outline map of California coast, showing locations of watersheds used in 

this study ........................................................................................................................................4

2. Suspended-sediment concentration versus discharge for the Santa Clara River............5

4. Fine-sediment fraction of suspended sediment versus discharge (Q) for the Santa 

Clara River......................................................................................................................................6

3. Grain-size distribution at three different discharges (Q) for the Santa Clara River..........6

5. Annual time series of fine-sediment flux from three largest river-sediment sources to 

the California coast ......................................................................................................................7

6. Sediment yield of global rivers, showing how yield increases as watershed area 

decreases ......................................................................................................................................8

7. Steps involved in extrapolation of regional average sediment yields to unmonitored 

watersheds, using mean yield from South Coast region rivers as an example.................8

8. Average annual fine-sediment flux from California coastal rivers, excluding input from 

San Francisco Bay......................................................................................................................10

10. Annual hydrographs for the Salinas River in 1938, and the Mississippi River in 1960....11

9. Regional distribution of annual fine-sediment flux from California coastal rivers ..........11

11. Outline map of California, showing percentages of historical record needed to account 

for 90 percent of total sediment load from coastal rivers....................................................12

12. Logarithmic bar charts showing influence of El Niño-Southern Oscillation (ENSO) and 

Pacific Decadal Oscillation (PDO) on discharge from several California rivers..............13

14. Outline map of southern California coast, showing proportions of fine-sediment flux 

from river sources and cliff and bluff erosion........................................................................15

13. Outline map of southern California coast, showing annual fine-sediment flux due to cliff 

and bluff erosion .........................................................................................................................15

15. California coast, showing turbid plumes offshore after a winter storm event.................16

16. Logarithmic plot of suspended-sediment concentration versus inplace and disaggregated inorganic grain size (DIGS) of sediment particles captured in the Eel River plume 

during a flood event....................................................................................................................16

17. Eel River-Humboldt Bay area, showing locations of turbid buoyant plume during storm 

event and poststorm flood deposit ..........................................................................................17

19. Fan and others’ model for fine-sediment transport offshore of the Eel River, constructed from integrated results of STRATAFORM project..................................................18

18. Eel River area, showing magnitude and direction of suspended-sediment transport 

along seabed offshore of river mouth during two storm events in winter 1996–97.........18

20. Model for fine-sediment-dispersal pathways during flood-event discharge from the 

Santa Clara River........................................................................................................................19

21. Time series of flood-layer thickness (in centimeters) in the Santa Barbara Channel 

offshore of the Santa Clara River after massive flood in January–February 1969 ..........19

22. Distribution of p,p′-dichlorodiphenyldichloroethylene (p,p’-DDE) on the continental 

shelf offshore of the Palos Verdes peninsula, plotted as integrated mass per unit area 

from sediment cores in upper 1 m of seabed.........................................................................19

23. Drainage areas of the Eel River, the Salinas River, and the Santa Clara River, showing 

locations of National Oceanic and Atmospheric Administration’s National Data Buoy 

Center buoys and U.S. Geological Survey gaging stations used in calculations ............20

24. Rose diagrams of wind direction and windspeed generated from hourly data during 

period 1982–2005 at National Oceanic and Atmospheric Administration’s National Data 

Buoy Center buoy 46022 near the Eel River............................................................................22
v

26. Bar charts showing fine-sediment-resuspension potential on the Eel River shelf, 

expressed as percentage of time when bottom-wave orbital velocity is higher than 0.2 

m/s, versus water depth ............................................................................................................23

25. Average river discharge, average significant wave height, average dominant wave 

period, and bottom-wave orbital velocity at water depths of 20, 40, 60, 80, and 100 m for 

all discharge events (n=70) of Q>500 m3/s from the Eel River.............................................23

27. Rose diagrams of wind direction and windspeed generated from hourly data during 

period 1987–2005 at National Oceanic and Atmospheric Administration’s National Data 

Buoy Center buoy 46042 near the Salinas River and Monterey Bay..................................24

29. Bar charts showing fine-sediment-resuspension potential off the Salinas River in 

Monterey Bay, expressed as percentage of time when bottom-wave orbital velocity is 

higher than 0.2 m/s, versus water depth.................................................................................25

28. Average river discharge, average significant wave height, average dominant wave 

period, and bottom-wave orbital velocity at water depths of 20, 40, 60, 80, and 100 m for 

all discharge events (n=21) of Q>100 m3/s from the Salinas River .....................................25

30. Rose diagrams of wind direction and windspeed generated from hourly data during 

period 1994–2004 at National Oceanic and Atmospheric Administration’s National Data 

Buoy Center buoy 46053 near the Santa Clara River............................................................27

32. Bar charts showing fine-sediment-resuspension potential off the Santa Clara River, 

expressed as percentage of time when bottom-wave orbital velocity is higher than 0.2 

m/s, versus water depth ............................................................................................................28

31. Average river discharge, average significant wave height, average dominant wave 

period, and bottom-wave orbital velocity at water depths of 20, 40, 60, 80, and 100 m for 

all discharge events (n=18) of Q>25 m3/s from the Santa Clara River................................28

33. Monterey Bay area, showing location of midshelf mud belt ..............................................29

34. Generalized stratigraphic profile of sediment accumulation in mud belt offshore of the 

Eel River........................................................................................................................................29

35. Outline map of California coast, showing distribution of sea-floor-sediment-sampling 

sites in regions 1 through 7 .......................................................................................................30

36. Outline map of California coast, showing distribution of fine-sediment content from 

sea-floor-sediment-sampling sites in usSEABED .................................................................32

37. Outline maps of California coast in areas of the Eel River shelf, Monterey Bay, and 

offshore of the Santa Clara River, showing distribution of fine-sediment content from 

sea-floor-sediment-sampling sites in usSEABED database................................................33

38. Water depth versus sea-floor-sediment grain size offshore of the Eel River shelf, 

Monterey Bay, and offshore of the Santa Clara River..........................................................34

39. Outline maps of California coast in area of the Eel River shelf, showing distribution of 

fine-sediment content from sea-floor-sediment-sampling sites in 

usSEABED database ..................................................................................................................35

40. Regional modern and Holocene sediment-accumulation rates on the California 

Continental Shelf in regions 1 through 7.................................................................................36

B1. Example of loess rating-curve weighting function ...............................................................43

B2. Loess rating curves of suspended-sediment concentration versus discharge for 

watersheds used in this study..................................................................................................44

C1. Loess rating curves of fine-sediment content versus discharge for watersheds used in 

this study, with ±2σ deviations shown for reference ...........................................................70
vi

Tables

1. U.S. Geological Survey gaging stations used in this study, listed from 

north to south ................................................................................................................................3

2. Regional mean annual fine-grained sediment loads from California 

coastal watersheds......................................................................................................................8

3. Mean annual sediment loads for California coastal rivers ...................................................9

4. Annual fine-sediment contribution from cliff/bluff erosion in central and southern 

California in comparison with fluvial sources........................................................................14

5. Regional sediment accumulation rates on the California continental shelf.....................34

A1. Wentworth-Krumbein scale of sediment-size classification.......................................................42

B1. Weighting factors (α values) of loess sediment-discharge rating curves for 

all the U.S. Geological Survey gaging stations used in this study, listed from 

north to south ..............................................................................................................................43

C1. Weighting factors (α values) of loess fine-sediment-fraction/discharge rating curves 

for all the U.S. Geological Survey gaging stations used in this study, listed from 

north to south ..............................................................................................................................70

D1. Fine-sediment input from cliffs and bluffs into various sections of the 

California coast...........................................................................................................................76
Executive Summary

We have investigated the sources, dispersal, and fate of 

fine sediment supplied to California coastal waters in a partnership between the U.S. Geological Survey (USGS) and the 

California Sediment Management Workgroup (CSMW). The 

purpose of this study was to document the rates and characteristics of these processes so that the State can better manage its 

coastal resources, including sediment. In this study, we made 

the following observations:

•	 Rivers dominate the supply of fine sediment to the 

California coastal waters, with an average annual flux 

of 34 megatonnes (Mt).

•	 Cliff and bluff erosion in central and southern California is a source of fine sediment, with a delivery 

rate of approximately 10 percent of river loads. In the 

southern most part of the State, however, where riversediment loads are low, cliff and bluff erosion represent 

approximately 40 percent of the total fine-sediment 

flux.

•	 Temporal variation in the sources of fine sediment is 

high. River floods and bluff erosion are episodic and 

dominated by winter storms, which supply most sediment flux to the coast. The magnitude of winter storms 

is generally related to the El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) 

climate cycles.

•	 The three rivers that dominate fine-sediment flux to the 

California coast are the Eel, Salinas, and Santa Clara 

Rivers. Because the sediment delivery from these and 

all other California coastal watersheds is episodic, 

individual rivers discharge most of their annual loads 

over the course of only a few days per year.

•	 Spatial variation in river-sediment discharge is high and 

generally related to such watershed characteristics as 

geology, precipitation, and drainage area. For example, 

the Transverse Range of southern California represents only 9 percent of the watershed-drainage area 

but 18 percent of the fine-sediment flux, a function of 

the young sedimentary bedrock and active tectonics 

of this region. The urban rivers of southern California 

were observed to discharge sediment at rates consistent 

with those of the surrounding Transverse Range rivers, 

which share the same geologic setting.

•	 Direct observations of fine-sediment dispersal have 

been limited to the river-mouth settings of the Eel and 

Santa Clara Rivers, where sediment has been observed 

to settle quickly from buoyant plumes and be transported along the seabed during periods of storm waves.

•	 After heavy loading of fine sediment onto the continental shelf during river floods, there is increasing evidence that fluid-mud gravity flows occur within a layer 

10 to 50 cm above the seabed and efficiently transport 

fine sediment offshore.

•	 All along the California coast, the timing of river discharge and coastal winds and waves from storm events 

are strongly coherent; however, of large wave events 

with the potential for resuspending and transporting 

fine sediment occur during periods without significant 

rainfall and therefore no significant river discharge.

•	 Although fine sediment dominates the midshelf mud 

belts offshore of California river mouths, these mud 

belts are not the dominant sink of fine sediment, much 

of which is deposited across the entire continental 

shelf, including the inner shelf, and offshelf into deeper 

water depths.

•	 Accumulation rates of fine sediment, which can exceed 

several millimeters per year, are generally highest near 

river sources of sediment and along the inner shelf and 

midshelf.

•	 Sediment-accumulation rates, as summarized from 

both long-term and recent investigations of continental-shelf geochronology, are generally consistent 

across California except in southern California, where 

recently the sediment-accumulation rate has been tenfold greater than the long-term rate, possibly as a result 

of increased river discharge, wastewater outfall inputs, 

or other anthropogenic sources.

Thus, fine sediment is a natural and dynamic element of 

the California coastal system because of large, natural sediment sources and dynamic transport processes.

Sources, Dispersal, and Fate of Fine Sediment Supplied to 

Coastal California

By Katherine L. Farnsworth and Jonathan A. Warrick
2 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

Introduction

The California Sediment Management Workgroup 

(CSMW) was established in 1999 to formulate regional 

approaches to protecting, enhancing, and restoring California’s coastal beaches and watersheds. The CSMW is a State 

and Federal partnership created to integrate ongoing work on 

multiple scales by many government agencies. The present study was funded through an agreement between the 

U.S. Geological Survey (USGS) and the CSMW to increase 

knowledge of the flux and fate of fine sediment delivered to 

the coastal ocean. The coastal delivery, dispersal, and fate of 

terrestrially derived fine sediment is important to characterize because (1) turbidity and sedimentation may affect marine 

biota, (2) the pathways and residence times of fine sediment in 

coastal waters are poorly understood, and (3) natural processes 

of sediment dispersal may be used as a model for the fate of 

human-introduced sediment in the coastal ocean.

Typically, four stages of sediment dispersal are evident on 

the continental shelf (Wright and Nittrouer, 1995): (1) initial 

supply, (2) initial deposition, (3) resuspension and transport, 

and (4) final deposition and long-term net accumulation. 

Much fine sediment is delivered to California coastal waters 

from such natural sources as rivers and bluffs; however, little 

is known about the amounts and timing of fine-sediment 

discharge, largely because of the attention focused on quantifying the delivery and transport of coarser (that is, sand size) 

material (for example, Inman and Jenkins, 1999; Warrick and 

Milliman, 2003; Willis and Griggs, 2003), particularly in relation to the stability of shorelines. Furthermore, little work has 

been conducted to evaluate the dispersal and fate of sediment 

along the entire California coastal margin.

The goal of this study is to fill these informational gaps 

through new calculations and a synthesis of existing data and 

results. We have used a sediment-budget technique throughout, 

with an emphasis on calculating the rates of sediment transport 

and flux of various portions of the sediment budget. Sediment 

budgets for coastal California have commonly been calculated 

on a littoral-cell basis, focusing on the coarser material that 

remains close to shore (for example, Willis and Griggs, 2003). 

However, the fine sediment delivered to the coastal ocean is 

not constrained to these littoral cells because it is more easily 

kept in suspension and transported long distances in buoyant 

freshwater plumes or far offshore along the seabed. Therefore, 

coastal fine-sediment budgets require a regional basis for 

proper analysis.

The following report is organized by the three main elements of fine-sediment for California coastal waters: sources, 

dispersal, and fate. After a brief discussion of fine-sediment 

properties, we discuss these three main elements in separate 

sections. In a final section we present our results with respect 

to a fine-sediment budget and identify future research needs.

What Is Fine Sediment?

Fine sediment is commonly defined by a particle-size 

threshold which, though somewhat arbitrary, approximately 

differentiates between particles that undergo suspendedload transport and those that undergo mixed bedload and 

suspended-sediment transport (McCave and Syvitski, 1991). 

Although various classification schemes exist, particle-size 

thresholds in all these schemes agree within a factor of 2. 

Here we use the Wentworth classification scheme because of 

its general acceptance across the geosciences (Boggs, 1987; 

McCave and Syvitski, 1991; Komar, 1998). In this scheme, 

fine sediment includes all particles with grain sizes smaller 

than 0.0625 mm in diameter, whereas sand ranges in grain size 

from 0.0625 to 2 mm (see app. A).

Fine sediment includes both silt and clay. Although the 

distinction between silt and clay is defined by a particle-size 

threshold of 0.002 mm, the silt- and clay-size particles typically have diverse physiochemical properties (Hillel, 1982). 

Thus, clay-size particles are generally dominated by clay minerals, which are the weathering products of primary, or sourcerock, minerals. Characteristics of clay minerals include their 

ability to exchange cations on the particle surface because of a 

negative charge, and their ability to absorb water. These properties are strongly influenced by the specific clay mineralogy 

and, thus, the source rock, weathering environment, and extent 

of weathering (Hillel, 1982). In contrast, silt-size particles are 

typically dominated by fragments of the source rocks without 

mineral alteration. Silt-size particles, however, have a much 

greater surface area per unit mass than sand and may be coated 

with clay-size particles, resulting in similar characteristics 

to clay (Hillel, 1982). For the purposes of this study, siltand clay-size particles have generally not been divided into 

separate size classes, owing to a lack of information regarding 

these distinctions in the data available.

Fine sediment has several other characteristics relevant 

to its transport and fate in the California coastal ocean. First, 

as discussed in further detail below, fine sediment commonly 

flocculates in seawater, a process that both increases the bulk 

particle size and enhances rates of vertical settling (Hill and 

others, 2000; Curran and others, 2002). Once deposited on the 

seabed, fine sediment may be ingested by benthic fauna and 

excreted as fecal pellets, packaging these small particles into 

larger, sand-size aggregates and altering their transport properties (Wheatcroft and Butman, 1997; Drake and others, 2002). 

Fine-sediment particles may also have materials adhering to 

their surfaces, allowing for dating by using radiometric tracers, or providing a means for nutrient and pollutant transport. 

These qualities can aid in the evaluation of sediment-transport 

pathways and sediment-accumulation rates, as discussed 

below, and may also lead to effects that are beneficial to the 

greater ecosystem of the California Current. For example, 

fine sediment on the continental shelf, originally derived from 

rivers, provides the dominant source of nutrient iron to phytoplankton in the California Current, which, in turn, provides 
Sources of Fine Sediment 3

the dominant source of primary production to this system 

(Johnson and others, 1999; Bruland and others, 2001; Buck 

and others, 2007). Finally, fine sediment is highly efficient at 

scattering light in suspension, causing turbidity and attenuating sunlight within seawater (Kirk, 1996). This may disrupt 

feeding or other life-history functions or marine biota (Anchor 

Environmental CA L.P., 2003), although this characteristic 

also allows for efficient measurement of suspended-sediment 

concentration with optical sensors. Together, these characteristics make fine sediment a dynamic and important constituent 

of the California coastal ocean.

Sources of Fine Sediment

Fluvial Sources

We calculated sediment input from rivers by using USGS 

stream-discharge records, which allow for a determination of 

the total suspended-sediment discharge from California coastal 

watersheds, as well as of the fine-sediment fraction. This study 

used multidecadal records from 25 coastal rivers (fig. 1; table 

1). Because of this, we used extrapolation techniques to estimate the fine-sediment flux from unmonitored areas or those 

with insufficient sediment data. Although some rivers (e.g., 

Santa Maria River) have extensive discharge records, they 

were not evaluated due to insufficient suspended-sediment 

concentration or grain-size information. An estimation of the 

inherent errors in calculating river-sediment load is discussed 

in detail below. We note that none of the rivers that drain into 

San Francisco Bay (including the Sacramento and San Joaquin 

Rivers and numerous smaller streams) have been considered in 

these estimates. Fine-sediment contributions from San Francisco Bay to the ocean are not accurately known, and no rigorous monitoring program has been conducted to measure fluxes 

through the Golden Gate. San Francisco Bay acts to modify 

the amount and timing of the sediment discharge from the Sacramento and San Joaquin Rivers and other streams draining 

into the bay. As an estuary, the bay allows transport of water 

and sediment both into and out through the Golden Gate during times of flood and ebb tides, respectively. Schoelhamer 

and others (2005) estimated an annual average net export of 

approximately 4 Mt of fine sediment out of the bay to the 

coastal ocean as a result of material delivered from rivers and 

streams, as well as eroded from the bay floor. Although this 

estimate is the best available at present, we note that it was 

calculated on the basis of accretion and erosion rates throughout the expanse of the estuary, not from direct measurements 

of suspended-sediment concentrations in the water passing 

through the Golden Gate.

Rating Curves

The USGS operates numerous gaging stations throughout 

California that measure river stage (height above a referenced 

datum), which is then converted to river discharge by using a 

stage-discharge rating curve, constructed from coincident measurements of both stage and discharge at a given station. Data 

are then reported as average daily flow rates and published 

in annual water-year (Oct. 1–Sept. 30) summaries, as well as 

online (URL http://waterdata.usgs.gov/nwis/). Operation and 

maintenance of the stream gages are standardized, as described 

by Rantz (1982). Although many U.S. rivers have been monitored for water discharge for a century or more, sediment-discharge data are relatively few and limited in scope. Also, many 

river-discharge stations have been removed and the coverage 

of small rivers reduced in recent years (Rantz, 1982).

Table 1. U.S. Geological Survey gaging stations used in this 

study, listed from north to south.

[USGS, U.S. Geological Survey]

Watershed

(fig. 1)

USGS

gaging

station

Length

of record

(yr)

Drainage

area

(km2

)

Smith River 11532500 73 1,590

Supply Creek 11530020 6 40

Trinity River 11530000 77 7,390

Klamath River 11523000 77 21,950

Redwood Creek 11482500 53 720

Mad River 11481000 57 1,260

Eel River 11477000 92 8,060

Russian River 11467000 65 3,470

Pine Creek 11460170 3 20

Pescadero Creek 11162500 53 120

San Lorenzo River 11160500 68 270

Salinas River 11152500 75 10,760

Carmel River 11143250 42 640

San Jose Creek 11120510 25 20

Ventura River 11118500 75 490

Santa Clara River 11114000 57 4,130

Calleguas Creek 11106550 23 640

Santa Ana River 11078000 80 4,400

San Juan Creek 11046550 16 300

San Mateo River 11046370 22 340

Santa Margarita River 11046000 74 1,920

San Luis Rey River 11042000 68 1,440

San Dieguito River 11030500 6 880

San Diego River 11022500 67 980

Tijuana River 11013500 46 4,390
4 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

0 50 100 KILOMETERS

Smith River

Trinity River

Klamath River

Redwood Creek

Mad River

Eel River

Russian River

Pine Creek

Pescadero Creek

San Lorenzo River

Salinas River

Carmel River

Santa Maria River

San Jose Creek

Ventura River

Santa Clara River

Calleguas Creek

Santa Ana River

San Juan Creek

San Mateo River

Santa Margarita River

San Luis Rey River

San Dieguito River

San Diego River Tijuana River

Figure 1. Outline map of California coast, showing locations of watersheds used in this study. Sediment loads from monitored 

watersheds (blue areas), for which both suspended-sediment-concentration and discharge data are available, were used to calculate 

watershed and regional rating curves; sediment loads from watersheds with insufficient data (green areas) were calculated from 

regional rating curves.
Sources of Fine Sediment 5

Suspended-sediment data are collected as flow-weighted, 

depth-integrated samples across a stream section and compiled 

into a single value (Guy and Norman, 1970). In contrast to 

water discharge, which is continuously or nearly continuously 

measured from stage-discharge recorders, suspended-sediment 

concentration is typically measured manually at fixed time 

intervals or during flood events. In the absence of these continuous sediment-discharge data, empirical relations, such as 

rating curves, have been used to estimate river-sediment loads; 

these curves describe the average relation between water-discharge rate and suspended-sediment concentration at a given 

station.

Numerous methods are available for quantifying 

sediment-discharge relations (Campbell and Bauder, 1940; 

Walling, 1977; Ferguson, 1987; Asselman, 2000). The 

sediment-discharge rating curves calculated for this study 

were constructed by a localized regression (“loess”) curvefitting technique, originally proposed by Cleveland (1979), 

that allows for a locally weighted polynomial regression to 

be calculated around each data point. As shown by Hicks 

and others (2000) and Warrick and others (2004a), this 

approach works well for small, steep rivers, such as those in 

California. At each point, a low-degree polynomial is fitted 

to a surrounding data subset (the subset window) by using a 

weighted-least-squares method, giving more weight to points 

near the center of the data subset and less weight to those on 

the subset margins. Further details of this method are provided 

in appendix B. Loess rating curves were calculated for each 

California coastal watershed on the basis of average-dailydischarge (Q) and suspended-sediment concentration (C) 

data from the USGS database (URL http://co.water.usgs.gov/

sediment/stationanchor.cfm). Residuals were analyzed for 

assurance of nonsystematic distributions in the estimation. 

Examples of loess rating curves and residual analyses for the 

Santa Clara River (fig. 1) are plotted in figure 2, and all the 

calculated loess rating curves and residual analyses are plotted 

in appendix B. A summary of error calculations from these 

data is included below.

Fine-Sediment Fraction

The amount and grain size of sediment transported by a 

river depend on the velocity and total discharge rate and the 

supply of sediment available to the river. In most rivers, suspended sediment makes up most (commonly >80 percent) of 

the total sediment load (Walling and Webb, 1981; Hadley and 

others, 1985). As river discharge increases, suspended-sediment concentration also commonly increases, and the grainsize distribution may also change (fig. 3). This distribution 

may become either coarser or finer with increasing discharge, 

depending on watershed and channel characteristics (Walling 

and Moorehead, 1989).

To account for the changing grain-size characteristics 

of rivers, we calculated the fine-sediment fraction of the total 

suspended-sediment load over a wide range of discharges for 

each river. Data were obtained from the USGS National Water 

Information System (NWIS)’s Water Quality section (URL 

http://waterdata.usgs.gov/nwis/). The temporal variation in 

grain-size distribution was quite large, especially for southern 

arid rivers. To account for this variation and to be able to apply 

grain-size distributions across a wide discharge range, a loess 

rating curve was used to relate the fine-sediment fraction of 

the suspended-sediment load to discharge. An example of a 

grain-size/discharge relation is plotted in figure 4, and all the 

fine-sediment-fraction/discharge curves are plotted in appendix C.

0

1

2

3

4

5

6

-4 -2 0 2 4

-3

-2

-1

0

1

2

3

A

LOGARITHM OF DISCHARGE

B

LOGARITHM OF SUSPENDED-SEDIMENT

CONCENTRATION RESIDUAL

Figure 2. Suspended-sediment concentration versus discharge 

for the Santa Clara River (fig. 1). A, Loess rating curve (red), with 

±2σ deviations (purple) shown for reference. B, Residuals of 

data points in figure 2A. Data from U.S. Geological Survey gaging 

station 11114000 (see fig. 23C for location). See appendix B for rest 

of calculated loess rating curves.
6 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

Q = 10 m3/s

0

20

40

60

80

100

<0.065.0625-.125.125-.25.25-.5.5-1

1-2

>2

GRAIN SIZE, IN MILLIMETERS

PROPORTION OF TOTAL 

SUSPENDED SEDIMENT, 

IN PERCENT

Q = 175 m3/s

<0.065.0625-.125.125-.25.25-.5.5-1

1-2

>2

Q = 730 m3/s

<0.065.0625-.125.125-.25.25-.5.5-1

1-2

>2

Figure 3. Grain-size distribution at three different discharges (Q) for the Santa Clara River (fig. 1), showing how suspended 

sediment varies with discharge. Data from U.S. Geological Survey gaging station 11114000 (see fig. 23C for location).

0 500 1,000 1,500 2,000 2,500

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

DISCHARGE, IN CUBIC METERS PER SECOND

FINE-SEDIMENT FRACTION 

OF SUSPENDED SEDIMENT

Figure 4. Fine-sediment fraction of suspended sediment versus 

discharge (Q) for the Santa Clara River (fig. 1), showing how 

suspended sediment varies with discharge, as shown in figure 3. 

Data from U.S. Geological Survey gaging station 11114000 (see fig. 

23C for location).

Error Calculations

Errors are inherent in all the calculations to determine the 

sediment delivery from rivers to the coastal ocean; the estimated accuracy of rating curves ranges from 30 to 50 percent 

(Komar, 1996; Willis and Griggs, 2003). For this study, we 

considered five types of errors to estimate the total error in calculating annual sediment delivery, as summarized below. Once 

determined, the sum of the squares of all errors was calculated 

to provide an envelope of confidence around annual estimates 

(Taylor, 1997).

Original Measurement and Reporting

Error in the original measurements stems from depthintegrated sampling methods based on the discharges estimated from stage-discharge rating curves. Yu (2000) stated 

that the average relative error of these curves is approximately 

8 percent, but some error is also present in the depth-integrated 

sampling method. Accordingly, we estimated a total measurement error of 10 percent (Guy and Norman, 1970; Wass and 

Leeks, 1999) for both of these errors together.

Sediment-Discharge Rating Curve

Error associated with the sediment-discharge rating 

curves was calculated at the same time as the loess rating 

curve for each river. Because the loess rating curve is calculated by using weighted local regression, the error for each 

estimate was calculated by using the standard error of estimate. This error was then associated with that portion of the 

loess rating curve and applied to estimates calculated from the 

sediment-discharge rating curve.

Extrapolation of Loess Rating Curve

Sediment-discharge rating curves were calculated by 

using the range of discharges represented by the sampling. 

However, it was common for there to be days when the discharge was higher or lower than values contained in the loess 

rating curve. Therefore, the loess rating curve was extrapolated 

by using the mean of the last five maximum/minimum values 

sampled. We estimate that an error of 10 percent was associated with this extrapolation, mostly from the extrapolation to 

higher values.
Sources of Fine Sediment 7

Fine-Sediment-Fraction/Discharge Relation

The error associated with accounting for the fine-sediment fraction was calculated in the same manner as for the 

sediment-discharge rating curve. The standard estimated error 

was calculated for the loess rating curve; this error was then 

applied to each of the estimates of daily sediment discharge.

Extrapolation of Fine-Sediment-Fraction/Discharge 

Relation

The fine-sediment-fraction/discharge relation was similar 

to the sediment-discharge rating curve in that discharges were 

larger or smaller than those used in calculating their relation. 

Therefore, we used the same extrapolation method in this relation as in the sediment-discharge rating curve. An error of 10 

percent was applied to measurements extrapolated to higher or 

lower values.

Calculation of Sediment Load

Daily sediment loads were calculated for each of the 

rivers in this study. Daily fine-sediment fluxes were calculated 

by using daily discharges, sediment-discharge rating curves, 

and fine-sediment-fraction/discharge relations. Daily sediment 

loads were then summed within each water year (Oct.–Sept.) 

to determine total annual sediment loads (fig. 5). Errors in 

these estimates were also calculated, allowing for determination of both a lower and an upper bound to annual sediment 

loads (table 3). Once these values were determined, fine-sediment yields were calculated and extrapolated to unmonitored 

watersheds, as discussed below.

Extrapolation to Unmonitored Watersheds

The region draining directly into the California coastal 

ocean (excluding San Francisco Bay and its tributaries) 

encompasses an area of slightly less than 100,000 km2, of 

which monitored watersheds account for 79 percent and 

unmonitored watersheds the remaining 21 percent (fig. 1). 

To extrapolate estimated sediment loads from monitored to 

unmonitored watersheds, we used sediment yield, defined as 

the average annual sediment load per unit area of watershed, 

equivalent to an average erosion rate (in millimeters per year).

For this study, we calculated sediment yields for monitored watersheds only on the basis of uncontrolled-watershed 

area (that is, the area downstream from any dams), assuming 

that negligible sediment passes through the dams, an assumption consistent with the coarse-sediment results of Willis and 

Griggs (2003). Although fine sediment would be more likely 

to pass through reservoirs than would sand-size sediment, 

owing to slower settling velocities, most structures built on 

the coastal watersheds in this study area are large enough to 

eliminate fine-sediment discharge. We then calculated regional 

sediment loads by extrapolating estimated sediment yields 

from monitored to neighboring unmonitored watersheds. Five 

regions of similar sediment yield were defined on the basis 

of similar geology and land use (Inman and others, 1998): 

(1) North Coastal Range rivers (49 percent of total land area; 

north of San Francisco Bay); (2) South Coastal Range rivers 

(22 percent of total land area; south of San Francisco Bay and 

north of the Santa Ynez River); (3) Transverse Range rivers 

(9 percent of total land area; from the Santa Ynez River to 

Malibu Creek); (4) Urban rivers (5 percent of total land area; 

south of Malibu Creek through Los Angeles to the Santa Ana 

River); and (5) Peninsular Range rivers (15 percent of total 

land area; from the Santa Ana River to the Tijuana River).

Measured sediment yields from each watershed were then 

used to estimate a mean regional sediment yield. One important issue to be taken into account when using an extrapolation 

of sediment yield from monitored to unmonitored watersheds 

is the well-described inverse relation between sediment yield 

and watershed area (fig. 6; Milliman and Syvitski, 1992). This 

issue is relevant because most unmonitored watersheds are the 

smallest along the California coast. To account for this condition, only the small monitored watersheds in each region were 

used to estimate regional sediment yields. A mean sediment 

yield was calculated for each region, along with estimates of 

upper and lower bounds (fig. 7A). These regional mean sediment yields were then applied to unmonitored watersheds to 

estimate the regional fine-sediment fluxes (fig. 7B). ANNUAL FINE-SEDIMENT LOAD , IN MEGATONNES

0

20

40

60

80

Eel River

0

5

10

15

20

Salinas River

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

0

10

20

30

40

Santa Clara River

WATER YEAR

Figure 5. Annual time series of fine-sediment flux from three 

largest river-sediment sources to the California coast (fig. 

1). Annual discharge from each of these rivers varies widely, 

regardless of sediment load.
8 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

Step 1: Regional sediment yields for small monitored watersheds are determined

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0 500 1,000

AREA OF UNDAMMED WATERSHED, IN SQUARE KILOMETERS

SEDIMENT YIELD, IN CENTIMETERS PER YEAR

Mean

A

Step 2: Regional means are then applied to unmonitored watersheds

Santa Cruz coastal creeks (watershed area, 200 km2)

High 0.047 94,000 150,400

Mean 0.030 60,000 96,000

Low 0.015 30,000 48,000

Sediment yield

(cm/yr)

Volume

(m3

/yr)

Mass

(t/yr)

B

DRAINAGE AREA, IN SQUARE KILOMETERS

SEDIMENT YIELD, IN TONNES PER 

SQUARE KILOMETER PER YEAR

106 101 102 103 104 105 107

102 106 105 104 103 101

>3000 m

1000-3000 m

500-1000 m

<500 m

EXPLANATION

Relief:

Figure 6. Sediment yield of global rivers, showing how yield 

increases as watershed area decreases. Curves are fitted for 

various watershed reliefs. After Milliman and Syvitski (1992).

Figure 7. Steps involved in extrapolation of regional average 

sediment yields (A) to unmonitored watersheds (B), using mean 

yield from South Coast region rivers (fig. 1) as an example. 

Uncertainty envelope in figure 7A is indicated by high and low 

estimates (gray areas).

Table 2. Regional mean annual fine-grained sediment loads from California coastal watersheds.

[All values in tonnes]

Region/cell Monitored

rivers

Unmonitored

rivers

Total

supply

North Coast region:

Input (t)

Proportion (percent)

13,667,000

72

5,320,000

28

18,987,000

South Coast region:

Input (t)

Proportion (percent)

2,146,000

38

3,502,000

62

5,648,000

Transverse Ranges:

Input (t)

Proportion (percent)

2,989,000

48

3,217,000

52

6,206,000

Urban rivers:

Input (t)

Proportion (percent)

140,000

6

2,221,000

94

2,361,000

Peninsular Ranges:

Input (t)

Proportion (percent)

288,000

71

116,000

29

404,000

River-Sediment Discharge

Overall, we calculate that an average of 34 Mt (range, 

15–60 Mt) of fine sediment is discharged by rivers to California coastal waters each year, excluding sediment from San 

Francisco Bay (fig. 8; table 2), on the basis of available discharge data for monitored watersheds (table 3), together with 

extrapolation to neighboring unmonitored watersheds (table2). 

Note that these values vary both spatially and temporally. The 

Eel River dominates the fine-sediment flux from all of coastal 

California with approximately 9 Mt/yr, or more than 25 
Sources of Fine Sediment 

9

Table 3. Mean annual sediment loads for California coastal rivers.[USGS, U.S. Geological Survey. Lower and upper bounds of fine-sediment load are based on error estimates]Watershed(fig. 1)

USGS

gagingstation

Length

of record (yr)

Drainage 

area (km2)

Lower

bound (t)

Mean annual

fine-sediment

load (t)

Upper

bound (t)

Total

suspendedsediment load (t)

Smith River 11532500 73 1,590 135,800 206,700 277,700 389,500

Supply Creek 11530020 6 40 1,200 4,100 7,000 9,700Trinity River 11530000 77 7,390 444,000 1,779,400 3,114,900 3,186,400Klamath River 11523000 77 21,950 741,100 1,211,800 1,682,400 1,761,700Redwood Creek 11482500 53 720 309,500 623,700 961,600 816,100Mad River 11481000 57 1,260 767,700 1,328,900 1,890,200 1,921,600Eel River 11477000 92 8,060 4,915,800 9,485,600 14,055,300 11,798,600Russian River 11467000 65 3,470 466,500 804,300 1,142,200 897,000Pine Creek 11460170 3 20 3,500 5,400 11,000 6,400Pescadero Creek 11162500 53 120 21,300 30,100 40,100 42,900San Lorenzo River 11160500 68 270 72,000 183,300 294,600 284,700Salinas River 11152500 75 10,760 851,000 1,752,500 2,654,100 2,211,200Carmel River 11143250 42 640 71,300 179,800 296,700 393,900San Jose Creek 11120510 25 20 – – 10,600 23,800 14,400Ventura River 11118500 75 490 – – 197,000 401,500 274,400Santa Clara River 11114000 57 4,130 283,100 2,152,200 4,021,200 3,092,100Calleguas Creek 11106550 23 640 435,500 628,700 822,000 883,900Santa Ana River 11078000 80 4,400 – – 140,500 305,600 237,000San Juan Creek 11046550 16 300 13,000 70,400 127,700 98,100San Mateo River 11046370 22 340 700 2,100 3,700 2,700

Santa Margarita River 11046000 74 1,920 27,600 66,500 109,000 79,800

San Luis Rey River 11042000 68 1,440 – – 20,800 58,000 46,000San Dieguito River 11030500 6 880 1,100 1,900 2,700 2,000San Diego River 11022500 67 980 11,300 16,000 21,500 16,500Tijuana River 11013500 46 4,390 – – 110,100 322,900 148,300
10 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

=1.5 Mt/yr

0 250 500 Km

Figure 8. Average annual fine-sediment flux from California coastal rivers (blue areas, 

monitored watersheds; green areas, unmonitored watersheds; see fig. 1 for locations), 

excluding input from San Francisco Bay, which is estimated at 4 Mt/yr. Size of arrows is 

proportional to total fine-sediment flux; black reference arrow corresponds to a value of 

1.5 Mt/yr. See tables 2 and 3 for details.

percent of the average total sediment flux from all of coastal 

California (fig. 8). North Coastal Range rivers dominate this 

fine-sediment flux, with greater than 50 percent originating 

from these watersheds, a rate approximately equivalent to this 

region’s proportion of the total coastal drainage area (fig. 9). 

The second-largest regional fine-sediment load is from the 

Transverse Range, with the Santa Clara River dominating the 

region (figs. 8, 9), which produces a disproportional amount 

of sediment (18 percent of load from only 9 percent of area), 

owing to its geology, land use, and tectonics (see Scott and 

Williams, 1978; Inman and Jenkins, 1999). The third-largest 

regional fine-sediment load is from South Coastal Range 

rivers, with the Salinas River dominating the region (fig. 9). 

Regional sediment discharge from Peninsular Range rivers is 

comparatively small with respect to the rest of the State, at an 

average rate of 0.4 Mt/yr (figs. 8, 9).

Urban rivers have sediment yields that are the second 

highest of the five regions and slightly less than Transverse 

Range rivers (fig. 9). An equivalent annual sediment yield 

should be expected for these regions, however, owing to their 

similar geologic settings (Scott and Williams, 1978; Inman 

and Jenkins, 1999). Thus, our results suggest a possibly slight 

decrease in annual sediment yield due to urbanization or other 

watershed differences. Urbanization in southern California has 

been shown to change the dominant areas of erosion within 

a watershed (Trimble, 1997). Another effect of urbanization 

may include increased stormwater runoff, which can decrease 

suspended-sediment concentrations (Warrick and Rubin, 

2007).

Sediment delivery from these coastal watersheds is 

extremely episodic. We see sharply rising and falling hydrographs during and after storms, mainly owing to the rapid routing of stormwater through the watersheds (fig. 10), resulting in 

episodic delivery of suspended sediment to the coastal ocean, 

and the delivery of much of the annual sediment load from 

these rivers within only a few days. For example, most rivers 

in southern California deliver 90 percent of the long-term 

fine-sediment load during less than 1 percent of the year (that 

is, in less than 4 days per year on average; fig. 11). Significant 

sediment discharge from central and northern California rivers, 

though still episodic, occurs over slightly longer periods (fig. 

11).

The number and magnitude of storm events during the 

year drives the transport and delivery of sediment from these 

rivers. The interannual variation in this “storminess” is driven 

by large-scale climatic forcings, which, in turn, can cause 

orders-of-magnitude variations in year-to-year fine-sediment 

fluxes (fig. 5). The El Niño/Southern Oscillation (ENSO) 

plays a key role in river flooding within southern California 

(Andrews and others, 2004). Recently, the 
Sources of Fine Sediment 11

North Coastal

Range

South Coastal

Range

Transverse 

Range

Urban rivers

Peninsular Range

North

Coastal

Range

Transverse

Range

Urban rivers

Peninsular Range

Load Area 

North Coastal Range 57 49 1.16

South Coastal Range 17 22 0.77

Transverse Range 18 9 2.00

Urban rivers 7 5 1.40

Peninsular Range 1 15 0.07

Region

Percentage of

total load

Percentage of

total area Load/area ratio

19

5.7

6.2

2.4

0.4

Total fine-sediment

load (Mt)

South Coastal

Range

Figure 9. Regional distribution of annual fine-sediment flux from California coastal rivers (fig. 1). 

Transverse Range rivers (Santa Barbara region) discharge a disproportionate amount of sediment 

from local watersheds, mostly owing to regional geology, whereas Peninsular Range rivers 

discharge much less sediment than would be predicted on the basis of watershed area alone.

0

2

4

8

51 101 151 201 251 301 351

DAILY SEDIMENT LOAD,

IN MEGATONNES

Salinas River

Mississippi River

6

10

1 51 101 151 201 251 301 351

DAY OF WATER YEAR

Figure 10. Annual hydrographs for the Salinas River (fig. 1) in 1938, which has a drainage area of 

about 11,000 km2, and the Mississippi River in 1960, which has a drainage area of about 3.3 million km2. 

Smaller rivers, especially those draining steep watersheds, have very steep rising and falling limbs on 

hydrographs, as shown by major flood event over the course of a few days on the Salinas River, whereas 

the Mississippi River has a much more protracted flood events, owing to its large drainage area. Water 

year is defined as October 1 through September 30.
12 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

influence of the Pacific Decadal Oscillation (PDO), an ENSOlike atmospheric/oceanic phenomenon in the North Pacific 

Ocean, has also been observed to be important to California 

river discharge (Mantua and others, 2002). These two largescale climatic phenomena, ENSO and PDO, are significantly 

correlated with annual discharge from California coastal rivers 

(fig. 12). When the warm phases of these phenomena occur, 

discharge from the rivers of southern and central California 

increases. The opposite is true in the Pacific Northwest, where 

the cool phases of ENSO and PDO result in greater river discharge (Mantua and Hare, 2002). Northern California appears 

to lie within the transition zone between the warm-phase 

region in the south and the cool-phase region in the north and 

thus shows an almost-equal importance of both the warm and 

cool phases (fig. 12).

Cliff and Bluff Sources

Many factors influence the delivery of fine sediment 

from coastal cliffs and bluffs, including, but not limited to, 

sea-level rise, degree of consolidation of the material, hardness 

of the material, wave climate in the area, protective barriers 

(natural or anthropogenic), tidal range, and ground-water flow. 

Approximately 72 percent of the California coastline consists 

of cliffs and bluffs (Patsch and Griggs, 2007), some of which 

are fronted by beaches and others not. Long-term rates of 

seacliff erosion are difficult to constrain, owing to wide spatial 

variation and the episodicity of seacliff failure (Komar, 1996). 

This variation, together with the size of the study area (fig. 1), 

adds to the complexity of estimation for this sediment source.

0 50 100 KILOMETERS

5-10

2-5

1-2

0-1

Percentage of

historical record 

EXPLANATION

Figure 11. Outline map of California, showing percentages of historical record needed to account for 

90 percent of total sediment load from coastal rivers. All the watersheds mentioned in this study are 

event driven, but sediment load from southern California rivers is extremely episodic because of the 

semi-arid environment.
Sources of Fine Sediment 13

Fine-sediment inputs from cliff and bluff erosion for this 

study were calculated on the basis of the work of Patsch and 

Griggs (2007), whose estimates of the volumetric erosion rate 

(VIC) were calculated by using the equation

VIC = cliff length × cliff height × 

cliff-erosion rate × grain-size fraction.

Patsch and Griggs calculated the contribution of sand-size 

material from cliff erosion, using estimated percentages of 

sand in the cliff and bluff material. Here we were interested 

in the fine-sediment fraction, and so we used an estimated 

percentage of fine sediment in the material instead, defined 

to be 100 percent minus the percentage of sand, assuming a 

negligible amount of grain sizes larger than sand (for example, 

gravel and cobbles).

Cliffs along the California coastline are commonly made 

up of multiple rock types. For example, bedrock is commonly capped with an alluvial deposit, whereby the equation 

becomes

VIC = (length × erosion rate × rock1 × %mud1) + 

(length × erosion rate × rock2 × %mud2)

= length × erosion rate × [(rock1 × %mud1) + 

(rock2 × %mud2)],

where rock1 and rock2 are the vertical heights of bedrock and 

alluvial deposits, respectively, and %mud1 and %mud2 are the 

percentages of these two rock types that are fine grained. The 

erosion rates used here were based on the locally determined 

long-term cliff-retreat rates calculated by Patsch and Griggs 

(2007). We note, however, that cliff retreat commonly occurs 

episodically and not always annually.

10 1 0.1 0.01 10 1 0.1 0.01 0.001

Tijuana River

San Luis Rey River

Santa Ana River

Santa Clara River

Salinas River

Russian River

Eel River

AVERAGE ANNUAL DISCHARGE, IN CUBIC KILOMETERS

A B

Figure 12. Logarithmic bar charts showing influence of El Niño-Southern Oscillation (ENSO) (A) and Pacific Decadal Oscillation (PDO) 

(B) on discharge from several California rivers (see fig. 1 for locations). Warm phases of ENSO and PDO shown with orange bars, and 

cool phases shown with blue bars. Discharge from rivers in southern California is strongly influenced by warm phases of both ENSO and 

PDO, whereas that from rivers in northern California is equally influenced by both warm and cool phases.
14 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

Using this framework, we calculated the annual contribution of fine sediment from cliffs and bluffs only for the region 

south of San Francisco Bay. Data coverage on grain size, erosion rate, and the heights of cliffs and bluffs in northern California is unavailable, and so we excluded this region from our 

analysis. Annual southern California cliff and bluff sedimentsupply rates range from approximately 0 to 400,000 m3

/yr (see 

app. D). Using a dry bulk density of 1,600 kg/m3 (Griggs and 

Hein, 1980) these sediment-supply rates are equivalent to a 

sediment load of approximately 0 to 660,00 Mt/yr, for a total 

sediment load of 1.3 Mt/yr (fig. 13). The largest input is from 

the Urban rivers region (Los Angeles area), owing to high 

erosion rates (~0.3 m/yr) and high mud content in the bedrock 

(fig. 13). Lower sediment-supply rates (120,000–190,000 

m3/yr) are observed in the South Coastal Range, Transverse 

Range (Santa Barbara), and Peninsular Range (San Diego) 

regions (fig. 13). Negligible fine sediment is supplied from the 

relatively pure eolian sand dunes of southern Monterey Bay 

(part of the South Coastal Range), which are rapidly eroding 

(0.5–1.5 m/yr; Thorton and others, 2006), but have little fine 

sediment.

Cliff and bluff sediment inputs account for anywhere 

from 0 to 36 percent of the regional fine-sediment supply, 

suggesting that bluffs are generally a secondary contributor 

of fine sediment to the California coastal ocean (fig. 14; table 

4), except for the Peninsular Range (San Diego region), which 

contributes 36 percent of the total fine-sediment flux of from 

cliff and bluff erosion. The Big Sur coastline (part of the South 

Coastal Range) may also contribute significant amounts of fine 

sediment from cliffs; however, even-fewer data are available 

from this region for estimating sediment load.

These results are based on regional rather than local characteristics of the cliffs and bluffs. If more precise values of the 

sediment load from cliffs and bluffs are desired for the coast, 

systematic analyses of the grain size of the material making up 

the cliffs and bluffs are needed. In addition, localized determination of the ease of erosion (hardness, degree of consolidation, presence or absence of internal weaknesses) and local 

processes (wave energy, storm frequency, protective barriers, 

ground-water flow, and so on) would improve our understanding of cliff-retreat rates (Benumof and Griggs, 1999; Young 

and Ashford, 2006) and sediment delivery to the coastal ocean.

Summary

Much fine sediment is delivered to the California coastal 

ocean from both rivers and coastal cliff and bluff erosion. 

Rivers dominate this sediment delivery with inputs ranging 

from 70 to 95 percent of regional fine-sediment budgets (fig. 

14). The largest sediment inputs are from the Eel, Salinas, and 

Santa Clara Rivers (fig. 1), which together discharge an average of approximately 13 Mt/yr (fig. 8; table 3), dominating 

their respective physiographic regions and accounting for 30 

to 50 percent of regional fine-sediment-budget inputs.

The fine-sediment inputs presented here need to be 

considered within the context of the episodicity of sediment 

delivery to the California coastal ocean. All California coastal 

rivers discharge episodically, with large proportions of their 

annual sediment loads delivered over the course of only a 

few winter days (fig. 11), and with wet winters dominating 

long-term sediment loading (fig. 10). Coastal cliff and bluff 

erosion is also episodic, mostly occurring during infrequent 

storm events (Storlazzi and Griggs, 2000). Owing to the small 

watershed areas and proximity to the coast, these storm events 

may occur simultaneously, resulting in the delivery of large 

amounts of material concurrently from both river sources and 

coastal cliff and bluff erosion. Acquisition of additional data 

on grain sizes and cliff-erosion rates, along with additional 

suspended-sediment monitoring during storm events, will 

allow a more accurate estimate of the sources of sediment 

delivered to the California coastal ocean.

Table 4. Annual fine-sediment contribution from cliff/bluff erosion in central and southern California in comparison with fluvial 

sources.

Region/cell Rivers Cliffs/bluffs Total supply

South Coast/Santa Cruz:

Input (t)

Proportion (percent)

2,188,000

92

195,000

8

2,383,000

Southern Monterey Bay:

Input (t)

Proportion (percent)

1,753,000

100

– –

– –

1,753,000

Transverse Range:

Input (t)

Proportion (percent)

5,335,000

95

307,000

5

5,642,000

Urban Rivers:

Input (t)

Proportion (percent)

2,809,000

6

658,000

94

3,467,000

Peninsular Range:

Input (t)

Proportion (percent)

404,000

64

224,000

36

628,000
Sources of Fine Sediment 15

South Coast / Santa Cruz

South Coast / South Monterey Bay

Transverse Range

Urban rivers

Peninsular Range

0 50 100 KILOMETERS

 = 0.4 Mt/yr

Negligible

South Coast/Santa Cruz

South Coast/Southern Monterey Bay

Transverse Range

Urban Rivers

Peninsular Range

0 50 100 KILOMETERS ffulB/ffilC laivulF

= 6.5 M t/yr

 Figure 13. Outline map of southern California coast, showing 

annual fine-sediment flux due to cliff and bluff erosion. Size of 

arrows is proportional to total fine-sediment flux; black reference 

arrow corresponds to a value of 0.4 Mt/yr. See table 4 for details.

Figure 14. Outline map of southern California coast, showing 

proportions of fine-sediment flux from river sources (gray sectors) 

and cliff and bluff erosion (black sectors). Size of circles is 

proportional to total fine-sediment flux; black reference circle 

corresponds to a value of 6.5 Mt/yr. See table 4 for details.
16 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

1 10 100 1,000

DIAMETER, IN MICROMETERS

SUSPENDED-SEDIMENT

CONCENTRATION, IN PERCENT

0.1

1

10

100

In place

DIGS

Figure 15. California coast, showing turbid plumes offshore 

after a winter storm event. National Aeronautics and Space 

Administration MODIS Aqua satellite image, taken January 12, 

2005.

Figure 16. Logarithmic plot of suspended-sediment 

concentration versus inplace and disaggregated inorganic 

grain size (DIGS) of sediment particles captured in the Eel River 

plume (fig. 1) during a flood event (from Geyer and others, 2004). 

Difference between inplace and DIGS data reflects effect of 

flocculation on particle size. Inplace flocs are broken apart during 

laboratory grain-size analysis.

Dispersal of Fine Sediment

Introduction

After sediment is introduced into coastal waters, it undergoes intervals of deposition, resuspension, and transport until 

it is ultimately deposited where it will no longer be disturbed 

(Wright and Nittrouer, 1995). At this point, the sediment 

becomes part of the geologic record (Drake, 1999). During 

this transit from source to sink, the pathways of dispersal are 

dominantly controlled by sediment-input rates, the physicaloceanographic regime, and the geometries of the margin.

In the previous section, we discussed fine-sediment 

supply to the California coast, and in this section we discuss 

sediment-dispersal processes before final deposition. First, we 

review the current understanding of coastal dispersal of fine 

sediment, with emphasis on research conducted offshore of the 

California coast. Most of this work has focused on the dispersal of river sediment because rivers are the dominant sediment 

source along this coastal margin and cliff and bluff failure 

events are difficult to observe. We then provide data and 

analysis to examine the potential for fine-sediment transport 

after river-discharge events along the California coast. A key 

element of these analyses is whether river sediment is delivered to the coast under unique oceanographic conditions that 

could affect the transport and dispersal of this material. If so, 

the transport of river-flood sediment may not be applicable to 

other fine-sediment-transport events. Alternatively, if river-discharge events are not unique oceanographically, then studies 

of the transport and dispersal of flood-derived sediment may 

be applicable to other fine-sediment sources.

Previous Investigations

As material is introduced into the coastal ocean from 

rivers, it is exposed to the saline waters of the ocean. Because 

freshwater is less dense than seawater, river water will 

typically enter the ocean as a buoyant plume (Wright and 

Nittrouer, 1995; Geyer and others, 2000). These buoyant 

plumes, which are commonly quite turbid, owing to fine sediment in suspension, have been observed to extend tens of kilometers from the California shoreline (fig. 15). However, mass 

balances of the sediment in these plumes suggest that, though 

turbid, the buoyant plumes offshore of the California coast 

rapidly lose sediment within kilometers of the river mouths 

(Geyer and others, 2000; Mertes and Warrick, 2001; Warrick 

and others, 2004b).

The rapidity of sediment loss from buoyant plumes is 

partly related to enhancement of settling rates due to flocculation of fine sediment (Geyer and others, 2004). The resulting 

flocs have low densities because of their large amounts of void 

space, and are considerably larger than the individual grain 

sizes within the floc (fig. 16). The resulting floc diameters are 

large enough to counteract the lower densities, resulting in 
Dispersal of Fine Sediment 17

Eel River

Humboldt

Bay

EXPLANATION

Tripod

Buoy

124.5° 124.3° 124.1°

41.0°

40.9°

40.8°

40.7°

40.6°

0 10 20 KILOMETERS

Figure 17. Eel River-Humboldt Bay area (fig. 1), showing 

locations of turbid buoyant plume during storm event (lightgray area) and poststorm flood deposit (dark-gray area; from 

Traykovski and others, 2000). A clear spatial discrepancy exists 

between plume, which occurs inshore of 40-m isobath, and 

deposit, which is centered between 60- and 90-m isobaths. 

Dots and triangles represent tripods and buoys instrumented to 

measure sediment-transport rates.

higher settling velocities (~1 mm/s) than those of individual 

particles (Hill and others, 2000). Laboratory investigations 

suggest that fine sediment in exceptional concentrations (>1 

g/L) may result in even higher rates of settling (~10 mm/s) 

due to convective instabilities (McCool and Parsons, 2004). 

Furthermore, a freshwater-sediment mixture with suspendedsediment concentrations higher than 40 g/L will be negatively 

buoyant in California coastal waters (Mulder and Syvitski, 

1995; Warrick and Milliman, 2003). Although California 

coastal rivers in flood stage commonly produce suspendedsediment concentrations higher than these reported thresholds 

(Warrick and Milliman, 2003), no field evidence exists to 

directly indicate the presence of negatively buoyant plumes. 

Once sediment settles from the buoyant plume, it will continue 

to settle through the water column toward the seabed, where it 

may be deposited or transported in suspension.

Thus, much of the fine sediment discharged to the 

California coast from rivers settles near the river mouths. A 

well-studied example is the Eel River shelf (fig. 1), where fine 

sediment is delivered to the ocean in a buoyant plume that 

hugs the shoreline as it is transported northward (Geyer and 

others, 2000; Pullen and Allen, 2000) resulting in considerable 

initial deposition of fine sediment shoreward of the 40-m isobath north of the river mouth (fig. 17). Much of this sediment 

is eventually transported offshore, however, to the midshelf 

mud belt that lies between the 60- and 90-m isobaths (fig. 17). 

This flux of sediment occurs by both resuspension and advection and by fluid-mud gravity flows along the seabed (Ogston 

and others, 2000; Traykovski and others, 2000), which result 

from overloading of suspended sediment in the bottom boundary layer and plunge offshore because of the combined effects 

of negative buoyancy and suspension by bottom-wave orbital 

velocities (Traykovski and others, 2000; Scully and others, 

2002; Harris and others, 2005; Wright and Friedrichs, 2006). 

Thus, fine-sediment transport on the Eel River shelf is greatly 

enhanced after river supply of sediment (fig. 18; Ogston and 

others, 2000), and sediment introduced to this margin may be 

moved over successive storm events as nearshore deposits of 

fine sediment are resuspended and transported offshore (fig. 

19; Fan and others, 2004).

Fine-sediment dispersal has been studied in only a few 

other California river-margin settings. Sediment dispersal 

from the Santa Clara River (fig. 1) was examined by satellite 

observation and ship-based sampling by Warrick and others 

(2004b). These results suggest that approximately 90 percent 

of the fine sediment is rapidly removed from the buoyant 

plume within 1 km of the river mouth during storm discharge 

(fig. 20). We note that the Santa Clara River discharges suspended sediment at much higher concentrations than the Eel 

River, possibly resulting in the enhanced settling rates discussed above. Seabed coring by Drake (1972) after the largest 

recorded storm discharges in the history of the Santa Clara 

River (~40 Mt during winter 1968–69) showed that most fine 

sediment was emplaced near the river mouth in deposits more 

than 15 cm thick (fig. 21). During the next year, however, this 

sediment continued to be transported seaward, as evidenced by 

a shift in the position of the sediment deposit. This observation indicates that the fine sediment discharged from the Santa 

Clara River may be resuspended and transported for many 

months after a discharge event, much like on the Eel River 

shelf.

An example of a study of fine-sediment transport in 

which the sediment source is not a river is the Palos Verdes 

margin (fig. 1), where effluent and landslide-derived sediment 

have mixed to create recent shelf deposits (Lee and Wiberg, 

2002). Movement of this effluent-derived sediment is important because it is contaminated with DDT-degradation products (fig. 22). Fine-sediment dispersal from the wastewater 

outfall is influenced by resuspension by waves and ambient 

currents (Noble and others, 2002; Sherwood and others, 2002; 

Wiberg and Harris, 2002; Wiberg and others, 2002). Resuspension of this material occurs an average of 10 times per 
18 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

Flooding and

initial plume fallout

Fluid mud

formation Continuing storm

resuspension and deposition

Flooding and

initial plume fallout

Storm resuspension and bypassing

Erosion

A

B

Figure 19. Fan and others’ (2004) model for fine-sediment transport offshore of the Eel River (fig. 

1), constructed from integrated results of STRATAFORM project (Nittrouer, 1999). Two transport 

regimes are identified: a high-concentration regime (A) that prevails during and immediately 

after flood events which introduce exceptional amounts of fine sediment, and a poststorm 

low-concentration regime (B) that prevails when shelf is no longer receiving flood-sediment 

input. During low-concentration regime, storm conditions resuspend sediment and transport it 

offshore, displacing flood deposit farther offshore.

A

0 10 20 KILOMETERS

0.5 g/cm/s

B

Figure 18. Eel River area (fig. 1), showing magnitude and direction of 

suspended-sediment transport along seabed offshore of river mouth during 

two storm events (D, fig. 18A; E, fig. 18B) in winter 1996–97 (after Ogston and 

others, 2000). Measurements were made at approximately 60-m water depth, and 

suspended-sediment transport was calculated as an integrated flux within 1.2 m 

above seabed. In both events, sediment transport during medium wave events 

peaked at 4-m wave height, although event E followed a river discharge with a 

peak flow of more than 11,000 m3

/s.
Dispersal of Fine Sediment 19

 s

Wind stress

Currents Mixing Settling

(~50 percent per day)

Turbid 

freshwater

Rapid sediment settling 

(>90 percent of 

sediment)

Freshwater 

hypopycnal plume

Nepheloid 

layer

Offshelf 

transport

River 

discharge

~1 km

Potential 

fluid mud and 

flood deposit 

NOT TO SCALE

A

B

C

Flood Sediment 

Thickness (cm)

>15 

10-15

5-10

2-5

1-2

<1 (P)

Absent (A)

SCR

SCR

SCR

EXPLANATION

Figure 20. Model for fine-sediment-dispersal pathways during flood-event discharge from the 

Santa Clara River (fig. 1; after Warrick and others, 2004a).

Figure 21. Time series of flood-layer thickness (in centimeters) in 

the Santa Barbara Channel offshore of the Santa Clara River (SCR; 

see fig. 1 for location) after massive flood in January–February 

1969 (after Drake, 1972). A, March–April 1969. B, May–August 

1969. C, February–June 1970. Dots, box cores. A, flood layer 

absent; P, flood layer present.

118° 25’ 118° 20’

33° 45’

33° 40’

10 2 3 4 5 KILOMETERS

Figure 22. Distribution of p,p′-dichlorodiphenyldichloroethylene 

(p,p′-DDE, a DDT-degradation product) on the continental shelf 

offshore of the Palos Verdes peninsula (from Lee and others, 2002), 

plotted as integrated mass per unit area from sediment cores in 

upper 1 m of seabed (squares). Whites Point outfalls were dominant 

source of p,p′-DDE.
20 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

46022

11477000

A

B

C

11152500

11114000

46042

46053

0 30 KILOMETERS 15

0 15 30 KILOMETERS

0 15 30 KILOMETERS

Figure 23. Drainage areas of the Eel River (A), the Salinas 

River (B), and the Santa Clara River (fig. 1), showing locations of 

National Oceanic and Atmospheric Administration’s National Data 

Buoy Center buoys (diamonds) and U.S. Geological Survey gaging 

stations (squares) used in calculations.

year at 60-m water depth and 3 times per year at 90-m water 

depth (Wiberg and others, 2002). The transport direction of 

this sediment, which is strongly influenced by the dominantly 

northwestward currents along this part of the continental shelf, 

results in deposition of contaminated sediment to the northwest of the outfall (fig. 22; Lee and others, 2002; Noble and 

others, 2002). This example of a nonriver setting reveals the 

effect of wave resuspension and ambient currents on fine-sediment dispersal on the California coastal margin.

Lastly, evidence exists that fine sediment can be resuspended and transported by ocean processes, such as internal 

bores related to tidal currents (for example, Noble and Xu, 

2003). These processes appear to be focused on the continental shelf slope break, however, where internal tidal bores can 

shoal. Understanding of these processes across the California 

coastal margin is incomplete, largely owing to their nonlinearity and limited observations.

Research Questions

River sediment is clearly delivered to California coastal 

waters during winter storms, and so it is relevant to examine 

whether these storms impart unique environmental forcings 

on the coastal waters that cause sediment transport at rates 

or water depths not observed at other times of the year. Here 

we examine whether the oceanographic conditions that occur 

during river-flood events are unique in comparison with the 

rest of the year. We analyze the three largest California coastal 

rivers with respect to sediment discharge: the Eel, Salinas, and 

Santa Clara Rivers (fig. 1), all of which coincidentally have 

National Oceanic and Atmospheric Administration (NOAA) 

weather buoys offshore of their mouths.

Techniques

We compared river-discharge data from USGS river 

gauges and oceanographic data from nearby NOAA National 

Data Buoy Center (NDBC) buoys (fig. 23) for the Eel, Salinas, 

and Santa Clara Rivers (fig. 1) to evaluate the characteristics of 

storm-discharge periods relative to the rest of the year. Hourly 

river-discharge, wind, and wave data were obtained and 

compared for all three regions. Discharge events were identified for each river on the basis of instantaneous river-discharge 
Dispersal of Fine Sediment 21

measurements exceeding a threshold value, defined from the 

long-term discharge record at each gauge and encompassing 

all historical flood events on each river. This threshold value is 

equal to the rate at which more than 75 percent of the historical water discharge and 95 percent of the historical sediment 

discharge occurred. Threshold values of 500, 100, and 25 m3/s 

were determined for the Eel, Salinas, and Santa Clara Rivers, 

respectively. Periods when instantaneous discharge (that is, 

15-minute discharge records) exceeded these thresholds were 

identified, and the 48 hours before and after the peak discharge 

were considered the “prestorm” and “poststorm” periods. 

These 48-hour periods were conservatively long storm periods 

for a single event, given that the river discharge abated within 

hours after peak discharge and that longer periods could 

include multiple events from different storms. Event time 

series were compared for each system, and the mean and variance of these event time series were calculated for discharge, 

significant wave height (Hmo), and dominant wave period 

(Tdom). From these wave data, bottom-wave orbital velocities 

were calculated for the seabed at 20-m increments from 20- to 

100-m water depth, based on linear wave theory (Dyer, 1986). 

These wave orbital velocities were compared with the critical 

threshold of particle entrainment (ucr). A conservative ucr value 

of 20 cm/s was used for fine sediment, based on the grain 

size of very fine sand (0.125 mm), to account for the minor 

cohesiveness of recently deposited fine sediment (Harris and 

Wiberg, 1997).

Results

Although geographic differences exist between the various systems, strong coupling is observed between river discharge, wind stress and direction, and wave climate at all sites. 

Below we detail the results by region from north to south, 

beginning with the Eel River (fig. 1).

Eel River

The Eel River discharges, on average, nearly 9.5 Mt of 

fine sediment annually to the coastal ocean. The initial fate 

of the sediment contained in this surface plume depends on 

surface currents set up by the wind before discharge (Pullen 

and Allen, 2000). On the Eel River shelf (fig. 1), the wind 

is generally from the north throughout the year; however, at 

significant times during the winter months the wind is from 

the south (figs. 24A, 24B). Immediately before and after times 

of peak discharge, winds are commonly strong and from the 

south (figs. 24C, 24D), setting up northward-moving surface 

currents that direct the river plume to the north, as discussed 

above (see fig. 17). After peak discharges, winds may be from 

the north and direct the tail end of the surface plume to the 

south (Pullen and Allen, 2000).

The sediment that is deposited on the seabed is then 

subjected to reworking by waves and currents. The influence 

of waves was examined to determine the potential for sediment resuspension and transport. Large discharge events (>500 

m3

/s) on the Eel River coincided with significant increases in 

wave height and relatively stable wave periods (fig. 25). As 

river discharge decreased, wave height concurrently decreased. 

These patterns result in slightly higher bottom-wave orbital 

velocities during peak discharge. Thus, during large discharge 

events, conditions in the receiving waters for the Eel River 

shelf are energetic. This temporal connection leads to bottomwave orbital velocities higher than the 20-cm/s threshold out 

to water depths of 80 to 100 m (fig. 25).

This energy regime is not unique, however, to times of 

large river discharge (fig. 26). On the Eel River shelf, bottomwave orbital velocities exceed the 20-cm/s threshold approximately 30 percent of the time at 60-m water depth, only partly 

accountable for by times of large discharge events (fig. 26A). 

Thus, the rest of the fall and winter seasons provide plenty of 

opportunities when bottom-wave orbital velocities are high 

enough to resuspend fine sediment (fig. 26B). In the shallower 

waters (<60 m deep) of this energetic shelf, even the summer 

months allow for resuspension and transport of fine sediment.

Salinas River

The Salinas River (fig. 1) discharges, on average, nearly 

2 Mt of fine sediment annually into Monterey Bay. Although 

this embayment is a different environment from that of the 

open Eel River shelf, similar forcings occur. Over the course 

of the year, dominant wind directions are from the northwest, 

with winter winds sometimes from the east-northeast (lighter) 

and south-southeast (stronger winds) (figs. 27A, 27B). Before 

river-flood discharge, however, winds are from a host of directions, although the strongest and most common winds are from 

the southeast. After river-flood events, winds are generally 

from the northwest (figs. 27C, 27D).

Any sediment initially deposited on the shelf offshore of 

the Salinas River mouth (fig. 1) is then subjected to reworking by waves and currents. Once again, patterns different from 

those on the Eel River shelf were observed. Wave heights peak 

before the arrival of river discharge and continue to fall over 

the course of the next 48 hours (fig. 28), although wave period 

varies little. Calculated bottom-wave orbital velocities show 

similar patterns to those of wave heights, with higher wave 

orbital velocities before peak discharge and falling during and 

after floods, leading to a decrease in sediment-resuspension 

potential during these flood events, reaching a maximum just 

before the influx of large amounts of sediment accompanying 

the peak discharge. This resuspension of fine sediment occurs 

to deeper than 60 m during the entire flood event (fig. 28D).

As on the Eel River shelf (fig. 1), wave energies high 

enough to resuspend material are not limited to flood events 

(fig. 29A). Sediment-resuspension potential is small during 

large river-discharge events and larger at other periods, though 

mostly during the energetic winter months (fig. 29B).
22 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

NORTH

SOUTH

WEST EAST

3%

6%

9%

12%

15%

Calms: 1.42% NORTH

SOUTH

WEST EAST

2%

4%

6%

8%

10%

(knots)

>= 22

17 - 21

11 - 17

7 - 11

4 - 7

1 - 4

NORTH

SOUTH

WEST EAST

4%

8%

12%

16%

20%

Calms: 0.17%

NORTH

SOUTH

WEST EAST

2%

4%

6%

8%

10%

Calms: 0.35%

A B

C D

EXPLANATION

Windspeed

Figure 24. Rose diagrams of wind direction and windspeed generated from hourly data during period 1982–2005 

at National Oceanic and Atmospheric Administration’s National Data Buoy Center buoy 46022 (fig. 23A) near the 

Eel River (fig. 1). A, All hourly data. B, Winter (Dec.–Feb.) hourly data. C, Hourly data for 48 hours before peak flow. 

D, Hourly data for 48 hours after peak flow.
Dispersal of Fine Sediment 23

0

2000

4000

3

4

5

11

12

13

14

-50 -40 -30 -20 -100 10 20 30 40 50 

0

0.5

1

1.5

TIME FROM PEAK DISCHARGE, IN HOURS

20m

60m

100m

AVERAGE 

Q, 

IN CUBIC METERS

PER SECOND

AVERAGE Hmo, 

IN METERS

AVERAGE Tdom,

IN SECONDS

Uwave,

IN METERS 

PER SECOND

80m

40m

Figure 25. Average river discharge (Q), average significant wave height (Hmo), average dominant wave 

period (Tdom), and bottom-wave orbital velocity (Uwave) at water depths of 20, 40, 60, 80, and 100 m for all 

discharge events (n=70) of Q>500 m3

/s from the Eel River (fig. 1). Solid curves, event-averaged values; dotdashed curves, ±2σ deviations. Below Uwave=0.2 m/s (gray area), resuspension of fine sediment is unlikely.

0

10

20

30

40

50

60

70

80

20 40 60 80 100

WATER DEPTH, IN METERS

20 40 60 80 100

WATER DEPTH, IN METERS

BOTTOM-SEDIMENT-RESUSPENSION POTENTIAL, 

IN PERCENTAGE OF TIME WHEN BOTTOM-WAVE ORBITAL

VELOCITY IS HIGHER THAN 0.2 METERS PER SECOND

A B

Winter

Spring

Summer

Autumn

EXPLANATION

Figure 26. Bar charts showing fine-sediment-resuspension potential on the Eel River shelf (fig. 1), expressed as 

percentage of time when bottom-wave orbital velocity (Uwave) is higher than 0.2 m/s, versus water depth. A, Finesediment-resuspension potential for nonflood periods (purple) and flood events (brown), defined as periods within 48 

hours before and after peak flow. B, Fine-sediment-resuspension potential during winter (Dec.–Feb.), spring (Mar.–

May), summer (June–Aug.), and autumn (Sept.–Nov.). Note that in shallower water, Uwave values are high enough to 

resuspend sediment year round, whereas in deeper water Uwave values are large enough almost exclusively in winter.
24 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

NORTH

SOUTH

WEST EAST

4%

8%

12%

16%

20%

Windspeed

(knots)

>= 22

17 - 21

11 - 17

7 - 11

4 - 7

1 - 4

Calms: 1.68%

NORTH

SOUTH

WEST EAST

2%

4%

6%

8%

10%

Calms: 1.18%

NORTH

SOUTH

WEST EAST

2%

4%

6%

8%

10%

Calms: 1.71%

NORTH

SOUTH

WEST EAST

3%

6%

9%

12%

15%

Calms: 1.41%

A B

C D

EXPLANATION

Figure 27. Rose diagrams of wind direction and windspeed generated from hourly data during period 1987–2005 

at National Oceanic and Atmospheric Administration’s National Data Buoy Center buoy 46042 (fig. 23B) near the 

Salinas River and Monterey Bay (fig. 1). A, All hourly data. B, Winter (Dec.–Feb.) hourly data. C, Hourly data for 48 

hours before peak flow. D, Hourly data for 48 hours after peak flow.
Dispersal of Fine Sediment 25

Figure 28. Average river discharge (Q), average significant wave height (Hmo), average dominant wave 

period (Tdom), and bottom-wave orbital velocity (Uwave) at water depths of 20, 40, 60, 80, and 100 m for 

all discharge events (n=21) of Q>100 m3

/s from the Salinas River (fig. 1). Solid curves, event-averaged 

values; dot-dashed curves, ±2σ deviations. Below Uwave=0.2 m/s (gray area), resuspension of fine 

sediment is unlikely.

0

10

20

30

40

50

60

70

80

90

20 40 60 80 100

WATER DEPTH, IN METERS

20 40 60 80 100

WATER DEPTH, IN METERS

BOTTOM-SEDIMENT-RESUSPENSION POTENTIAL, 

IN PERCENTAGE OF TIME WHEN BOTTOM-WAVE ORBITAL

VELOCITY IS HIGHER THAN 0.2 METERS PER SECOND

A B

Winter

Spring

Summer

Autumn

EXPLANATION

Figure 29. Bar charts showing fine-sediment-resuspension potential off the Salinas River in Monterey Bay (fig. 1), expressed 

as percentage of time when bottom-wave orbital velocity (Uwave) is higher than 0.2 m/s, versus water depth. A, Finesediment-resuspension potential for nonflood periods (purple) and flood events (brown), defined as periods within 48 hours 

before and after peak flow. B, Fine-sediment-resuspension potential during winter (Dec.–Feb.), spring (Mar.–May), summer 

(June–Aug.), and autumn (Sept.–Nov.). Note that in shallower water, Uwave values are high enough to resuspend sediment 

year round, whereas in deeper water Uwave values are large enough almost exclusively in winter.

0

200

400

600

2

3

4

10

12

14

16

0

0.5

1

20m

60m

100m

TIME FROM PEAK DISCHARGE, IN HOURS

AVERAGE 

Q, 

IN CUBIC METERS

PER SECOND

AVERAGE Hmo, 

IN METERS

AVERAGE Tdom,

IN SECONDS

Uwave,

IN METERS 

PER SECOND

40m

80m

-50 -40 -30 -20 -10 0 10 20 30 40 50 
26 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

sediment may be resuspended and transported occurs almost 

entirely when river discharge is low. Thus, although most 

investigations of sediment transport and dispersal offshore of 

California have been in river-dominated settings, river floods 

by themselves have no unique sediment-transport forcings 

with respect to waves. We suggest that observations of the 

dispersal of fine sediment from rivers, especially transport 

along the seabed, may be applicable to the dispersal of sediment from other sources along the coast (for example, bluff 

erosion and sewer outfalls). This sediment transport will be 

influenced by the gradient in wave energy along the California 

coast, which is generally strongest in the north and weakest in 

the south. Local seabed topography, wave climate, currents, 

and sediment sources will greatly influence sediment transport 

in these coastal settings.

Fate and Accumulation of Fine 

Sediment

Introduction

Deposition, burial, and long-term accumulation of fine 

sediment mark the final stage of dispersal of sediment to the 

continental margin (Wright and Nittrouer, 1995). Sediment 

accumulates across the continental shelf and commonly into 

deeper parts of the ocean, as dictated by sediment sources, 

oceanographic processes, and coastal morphology. In coastal 

settings with an adequate supply of fine sediment, a sand-mud 

transition may occur over a narrow depth range (McCave, 

1972; Stanley and others, 1983; George and others, 2006). 

The depth of this sand-mud transition is primarily related to 

wave height but also to sediment source and shelf geometry. 

Offshore of the sand-mud transition, fine sediment may accumulate within a region commonly called the midshelf mud belt 

(fig. 33). Midshelf mud belts have several distinguishing characteristics: high accumulation rates of fine sediment, elongate 

shape in the alongshore direction, and low slopes. Along the 

west coast of North America, mud belts have been described 

offshore of the Columbia, Eel, and Russian Rivers (Griggs and 

Hein, 1980; Nittrouer and Sternberg, 1981; Drake and Cacchione, 1985; Wheatcroft and others, 1997) and surrounding 

Monterey Bay (Edwards, 2002; Eittreim and others, 2002a).

Although midshelf mud belts are prevalent offshore of 

many Western U.S. rivers, the following two points should 

also be considered: (1) sand can also accumulate in these mud 

belts, and (2) mud belts are not the only sites of fine-sediment 

accumulation. An example of interbedding of sand and fine 

sediment in the mud belt offshore of the Eel River (fig. 1) was 

described by Fan and others (2004), as illustrated in figure 

34. Clay-rich beds are deposited after river-flood-influenced 

transport events (or the “high-concentration regime”), whereas 

sand-rich beds are deposited after nonflood events (or the 

“low-concentration regime”).

Santa Clara River

The Santa Clara River (fig. 1) provides yet another 

example of how physical forcings may control the dispersal 

of sediment from rivers on the California coast. The Santa 

Clara River discharges, on average, approximately 2 Mt of fine 

sediment annually, more than 90 percent of which is delivered 

over the course of just a few days a year. In the Santa Barbara Channel region near the mouth of the Santa Clara River, 

winds are dominantly from the west throughout the year (fig. 

30A). During the winter, winds from east to east-southeast are 

commonly strong and associated with storm events (fig. 30B). 

The days before peak discharge are characterized by winds 

from the east-southeast (fig. 30C), immediately followed by 

winds from the west (fig. 30D). Thus, the Santa Clara River is 

unusual in that local winds are oriented east-west, and strong 

winds are from the west (that is, from upcoast) after river 

events.

Wave energies in the Santa Clara River mouth (fig. 1) 

are not as high as those off either the Salinas or Eel River 

(fig. 31). However, the significant wave height changes little 

during river events, whereas a depression is observed in the 

dominant wave period just before peak discharge (fig. 31), 

possibly owing to winds from the southeast and locally generated waves. Because of these patterns, bottom-wave orbital 

velocities peak within 15 hours of peak discharge (fig. 31), 

although this peak in bottom-wave orbital velocities does not 

extend to the same water depths offshore of the Eel or Salinas 

River systems, owing to the lower significant wave heights. 

Little sediment resuspension is observed offshore of the Santa 

Clara River deeper than 60 m during flood events (fig. 31).

Sediment-resuspension potential on the Santa Clara 

River shelf (fig. 1) due to high wave orbital velocities is much 

smaller than in the Eel and Salinas systems because of lower 

wave heights. Sediment-resuspension potential can be greater, 

however, during periods of insignificant river discharge, similar to the Eel and Salinas Rivers. Such periods of enhanced 

sediment-resuspension potential are most common in the 

winter and rarely affect water depths below 60 m (fig. 32).

Summary

The dispersal of fine sediment discharged onto the California continental shelf appears to occur in multiple resuspension-transport events that may continue over a period of weeks 

to more than a year. These resuspension/transport events occur 

dominantly during periods of large waves, which provide 

bottom-wave orbital velocities high enough to resuspend fine 

sediment from the seabed. Observations of sediment dispersal 

from river systems suggest that after somewhat brief advection 

in a buoyant plume (~hours), suspended-sediment transport 

along the seabed is the most important process for transporting fine sediment across the shelf. Although coherent temporal patterns exist in winds, waves, and river discharge, the 

potential to suspend and transport fine sediment during river 

floods is not unique to these events. Rather, periods when fine 
Dispersal of Fine Sediment 27

NORTH

SOUTH

WEST EAST

3%

6%

9%

12%

15%

Calms: 1.23%

NORTH

SOUTH

WEST EAST

2%

4%

6%

8%

10%

Calms: 1.68%

NORTH

SOUTH

WEST EAST

3%

6%

9%

12%

15%

Calms: 0.71%

NORTH

SOUTH

WEST EAST

3%

6%

9%

12%

15%

Calms: 0.29%

A B

C D

Windspeed

(knots)

>= 22

17 - 21

11 - 17

7 - 11

4 - 7

1 - 4

EXPLANATION

Figure 30. Rose diagrams of wind direction and windspeed generated from hourly data during period 1994–2004 at 

National Oceanic and Atmospheric Administration’s National Data Buoy Center buoy 46053 (fig. 23C) near the Santa 

Clara River (fig. 1). A, All hourly data. B, Winter (Dec.–Feb.) hourly data. C, Hourly data for 48 hours before peak flow. 

D, Hourly data for 48 hours after peak flow.
28 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

0

100

200

1

2

3

5

10

15

-50 -40 -30 -20 -10 0 10 20 30 40 50 

0

0.5

1

TIME FROM PEAK DISCHARGE, IN HOURS

20m

60m

100m

AVERAGE 

Q, 

IN CUBIC METERS

PER SECOND

AVERAGE Hmo, 

IN METERS

AVERAGE Tdom,

IN SECONDS

Uwave,

IN METERS 

PER SECOND

80m

40m

Figure 31. Average river discharge (Q), average significant wave height (Hmo), average 

dominant wave period (Tdom), and bottom-wave orbital velocity (Uwave) at water depths of 20, 

40, 60, 80, and 100 m for all discharge events (n=18) of Q>25 m3

/s from the Santa Clara River (fig. 

1). Solid curves, event-averaged values; dot-dashed curves, ±2σ deviations. Below Uwave=0.2 

m/s (gray area), resuspension of fine sediment is unlikely.

0

10

20

30

40

50

20 40 60 80 100

WATER DEPTH, IN METERS

20 40 60 80 100

WATER DEPTH, IN METERS

BOTTOM-SEDIMENT-RESUSPENSION POTENTIAL, 

IN PERCENTAGE OF TIME WHEN BOTTOM-WAVE ORBITAL

VELOCITY IS HIGHER THAN 0.2 METERS PER SECOND

A B

Winter

Spring

Summer

Autumn

EXPLANATION

Figure 32. Bar charts showing fine-sediment-resuspension potential off the Santa Clara River (fig. 1), expressed as 

percentage of time when bottom-wave orbital velocity (Uwave) is higher than 0.2 m/s, versus water depth. A, Fine-sedimentresuspension potential for nonflood periods (purple) and flood events (brown), defined as periods within 48 hours before and 

after peak flow. B, Fine-sediment-resuspension potential during winter (Dec.–Feb.), spring (Mar.–May), summer (June–

Aug.), and autumn (Sept.–Nov.). Note that in shallower water, Uwave values are high enough to resuspend sediment year 

round, whereas in deeper water Uwave values are large enough almost exclusively in winter.
Fate and Accumulation of Fine Sediment 29

Ample evidence exists that midshelf mud belts are not 

the only sites of fine-sediment deposition. For example, the 

Eel River mud belt has been estimated to receive only 20–25 

percent of the total fine-sediment discharge from the Eel River 

(fig. 1; Wheatcroft and others, 1997). The remaining fine sediment is either transported past the shelf break to the slope or 

through the Eel Canyon, or deposited on the Inner continental 

shelf. Crockett and Nittrouer (2004) estimated the inner-shelf 

deposition (defined as 20–55-m water depth) of fine sediment 

from the Eel River at 6–13 percent of the total fine-sediment 

load of the river. The total sedimentation rate on the inner 

shelf was estimated at 13 to 33 mm/yr since 1964, within 

which approximately 10 percent is fine sediment that occurs in 

both thin flood deposits and mixed into the sand (Crockett and 

Nittrouer, 2004). Thus, a mass balance of fine sediment for 

the Eel River margin suggests that approximately 10 percent 

accumulates on the inner shelf (<55-m water depth; Crockett 

and Nittrouer, 2004), approximately 20 percent on the midshelf and outer shelf (50–150-m water depth; Sommerfield and 

Nittrouer, 1999), and approximately 20 percent on the upper 

continental slope (150–600-m water depth; Alexander and 

Simoneau, 1999). The remaining approximately 50 percent of 

sediment load is likely transported down the Eel Canyon (Mullenbach and others, 2004) onto the Eel Fan or offshore of the 

upper continental slope.

In this section, we present a thorough analysis of grainsize distributions and sediment-accumulation rates on the 

California continental shelf. The purpose is to describe where 

fine sediment accumulates, how its location varies along the 

coast, and why such variation occurs. As described below, we 

used existing data from the USGS usSEABED database (URL 

http://walrus.wr.usgs.gov/usseabed/) and other published 

reports to describe the patterns of fine-sediment accumulation. 

Two tasks were addressed: (1) mapping and analysis of finesediment distributions offshore of California and (2) synthesis 

of published fine-sediment-accumulation rates in the study 

area (fig. 1).

Techniques

The grain size of the seabed was characterized by using 

physical and virtual (photographic and video) samples from 

seabed cores and grab samples summarized in the usSEABED 

database (Reid and others, 2006), which provides integrated 

numeric data based on existing small and large marine 

research efforts. This database includes surficial and subbottom numeric information on grain size, composition, and 

applied properties obtained from core logs, sample descriptions, photographs, and videos, as well as the more standard 

numeric data from laboratory analyses.

Here we use grain-size data from physical samples of the 

seabed surface contained in the usSEABED database. Two 

general types of seabed samples were used in our analyses: 

those with only verbal descriptions and those with laboratory 

grain-size analyses. Although laboratory data exist for many of 

the samples, exclusive use of these data would exclude nearly 

a third of the California coastline (fig. 35). Thus, for mapping 

purposes, we included both sample types, although for statistical analyses we only used the laboratory analyses. Grain-size 

information from verbal descriptions has been extracted (or 

“parsed”) by using fuzzy-set theory, as explained by Reid and 

others (2006).

Sediment-accumulation data, which have been synthesized from available published records, were derived from 

either sediment cores or seismic-reflection surveys. Here 

Moss Landing

Salinas R.

Monterey

Pajaro R.

Santa Cruz

San Lorenzo R.

122°15’ 122° 121°45’

37°

36° 45’

Figure 33. Monterey Bay area (fig. 1), showing location of 

midshelf mud belt (from Eittreim and others, 2000).

Deposits of 

low-concentration 

regime

Deposits of 

high-concentration 

regime

Deposits of 

low-concentration 

regime

Multiple-event, reverse-graded,

bioturbated sand bed

Upward-fining, sand-rich storm beds

Multiple-event, reverse-graded,

bioturbated sand bed

Unsorted, clay-rich 

storm beds, flood debris

Multiple-event, reverse-graded,

bioturbated sand bed

Upward-fining, sand-rich storm beds

Figure 34. Generalized stratigraphic profile of sediment 

accumulation in mud belt offshore of the Eel River (fig. 1; from Fan 

and others, 2004). Beds of clay-rich sediment alternate with sandy 

beds, representing deposition after flood (high-concentration 

regime) and nonflood (low-concentration regime) events.
30 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

Numeric data, parsed from descriptive information

Derived data, extracted from laboratory analyses

EXPLANATION

Data Type

1

2

3

4

5

6 7

0 50 100 KILOMETERS

Figure 35. Outline map of California coast, showing distribution of sea-floor-sediment-sampling sites (dots; Reid and 

others, 2006) in regions 1 through 7. Dots, data types: yellow, numeric data parsed from descriptive information; red, 

derived data extracted from laboratory analyses.
Fate and Accumulation of Fine Sediment 31

we define “recent” (<100 yr) accumulation rates to be those 

derived largely from isotopic profiles of 210Pb and (or) 137Cs 

within sediment profiles, according to the techniques summarized by Nittrouer and others (1979) and Sommerfield and 

Nittrouer (1999). The “long term” (>1,000 yr) sediment-accumulation rates presented here are from either seismic profiles 

of the continental shelf, which use a strong basement reflector as the Holocene transgressive surface, or from 14C dating 

of samples from within sediment cores (Schwalbach and 

Gorsline, 1985). Data have been summarized into three shelf 

regions on the basis of the water depth of the sample—inner 

shelf (<50-m depth), midshelf (50–100 m depth), and outer 

shelf (>100-m depth)—and into seven physiographic regions 

along the State (fig. 35).

Grain Size on the California Continental Shelf

Data on more than 19,200 grain-size samples from the 

seabed surface offshore of California are available in the 

usSEABED database, of which more than 7,650 records 

contain laboratory grain-size information (fig. 35). Fine sediment occurs throughout the sampled regions (1–7, fig. 35) but 

generally dominates the midshelf, especially offshore of major 

coastal rivers (fig. 36). The inner shelf generally has much-less 

fine sediment for most of California except in southern California, as discussed below. The continental shelf offshore of 

San Francisco Bay is notably devoid of fine sediment (fig. 36), 

whereas the interior of the bay is dominated by it. Below we 

present three examples from the continental shelf immediately 

offshore of the three rivers with the greatest sediment supply, 

the Eel, Salinas, and Santa Clara Rivers.

The grain size of sediment offshore of the Eel River 

(fig. 1) clearly reveals a transition from dominantly sand on 

the inner shelf to dominantly fine sediment on the midshelf 

to outer shelf (fig. 37A). The midshelf mud belt, which was 

the focus of the large research program STRATAFORM 

(Nittrouer, 1999), is observable to the north of the river mouth 

(fig. 37A), and fine sediment is present on much of the outer 

shelf and continental slope offshore of the mud belt. These 

grain-size relations with water depth can be observed in a statistical summary of the samples (fig. 38A). Sediment inshore 

of 50-m water depth is dominated by sand-size and coarser 

particles (fig. 38A). Below 50-m water depth, the seabed is 

much more likely to be dominated by fine sediment, except 

largely on the narrow, canyon-dominated shelves south of the 

river mouth (fig. 37A).

The continental shelf of Monterey Bay, which receives 

sediment inputs from the Salinas River and numerous small 

coastal rivers, displays similar sediment grain-size patterns 

to the Eel River shelf (figs. 1, 37B). The inner parts of the 

Monterey Bay shelf are dominated by sand, whereas a distinct 

fine-sediment region is present in the midshelf (fig. 37B), 

except in the southern most part of Monterey Bay, where the 

shelf is dominated by sand (fig. 37B). The outer shelf and 

upper continental slope have little fine sediment, in contrast to 

the muddy slope off the Eel River. These patterns are consistent with the interpretations by Eittreim and others (2002b), 

as illustrated in figure 33. Summarized by water depth, sand 

and coarser sediment dominates the sea floor inshore of 40-m 

water depth, whereas fine- sediment dominates the regions 

between 40- and 110-m water depth (fig. 38B). Below approximately 110-m water depth, the sediment is much coarser (fig. 

38B).

The Santa Barbara Channel and Santa Monica Bay lie 

offshore of the Santa Clara River and several other small rivers 

in southern California (figs. 1, 37C). The grain-size distributions of this region differ considerably from those in northern 

and central California, as discussed above. Fine sediment is 

observed to dominate the seabed throughout the region, but 

little depth control is observed in these data (figs. 37C, 38C). 

Unlike the other systems discussed above, fine sediment is 

observed to dominate some of the samples from above 30-m 

water depth (fig. 38C). Sand-dominated regions of the shelf 

occur on the southern Ventura shelf, near Point Conception, 

and around the offshore islands. Southern California has no 

clear and consistent sand-mud transition (fig. 37C), likely 

because of variations in wave energy, sediment sources, currents, and shelf morphology.

An important characteristic of all three regions is that 

fine sediment is present in most seabed samples, even from 

the shallowest depths (fig. 38), a result consistent with the 

observations of Crockett and Nittrouer (2004) and suggesting 

that although relatively distinct sand-mud transitions can occur 

on the continental shelf, significant amounts of fine sediment 

lie inshore of these transitions. This characteristic appears to 

be especially important in southern California, where wave 

energy is significantly smaller than in northern California and 

where more fine sediment has been measured on the inner 

shelf (fig. 38C). Local variations in grain size may be related 

to temporal changes in the sediment deposited by either burial, 

erosion, or winnowing, as observed in grain-size samples from 

the Eel River shelf (fig. 37A). Assessment of the three years 

with the greatest amount of sampling indicates that seabed 

samples collected in 1998 contained less fine sediment than in 

1995 or 1997 (fig. 39), consistent with the conceptual model 

of Fan and others (2004), as illustrated in figure 34, and with 

the sampling results of Drake (1972), as illustrated in figure 

21, suggesting that the grain size of the seabed can be dynamic 

and respond to external forcing of river inputs and ocean 

conditions.

Fine-Sediment-Accumulation Rates

Sediment that is deposited on the continental shelf and 

buried by subsequent deposition forms the geologic record that 

can be evaluated for such characteristics as accumulation rates. 

Rates of fine-sediment accumulation offshore California have 

been estimated by using both isotopic records within sediment 

cores and seismic-reflection data, as plotted in figure 40 and 

summarized in table 5. For this summary, we divided 
32 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

0 50 100 KILOMETERS

0 - 10

10 - 20

20 - 30

30 - 40

40 - 50

50 - 60

60 - 70

70 - 80

80 - 90

90 - 100

EXPLANATION

Fine grained sediment content

(volume percent)

Area of

figure

37 A

Area of

figure

37 B

Area of

figure

37 C

Figure 36. Outline map of California coast, showing distribution of fine-sediment content from sea-floor-sedimentsampling sites (dots) in usSEABED.
Fate and Accumulation of Fine Sediment 33

0 25 50 KILOMETERS

0 - 10

10 - 20

20 - 30

30 - 40

40 - 50

50 - 60

60 - 70

70 - 80

80 - 90

90 - 100

Fine sediment content

(volume percent)

A EXPLANATION

Figure 37. Outline maps of California coast (fig. 1) in areas of the 

Eel River shelf (A), Monterey Bay (B), and offshore of the Santa 

Clara River (C), showing distribution of fine-sediment content from 

sea-floor-sediment-sampling sites (dots) in usSEABED database 

(Reid and others, 2006).

0 25 50 KILOMETERS

B

0 25 50 KILOMETERS

C

California into seven regions that represent the sites of major 

studies. The most thorough investigations have been on the 

Eel River shelf (region 1, fig. 35) and in the Santa Monica Bay 

(region 6), whereas the other regions have received only localized or no investigations (table 5).

Sediment-accumulation rates are generally highest on the 

inner shelf (<50-m water depth) and decrease with depth, most 

obviously on the Eel River shelf and in Santa Monica Bay 

(regions 1 and 6, respectively, fig. 35), although this result is 

consistent across all regions (fig. 40). The highest sedimentaccumulation rates anywhere on the shelf were observed 

offshore of the Eel River (region 1), which also receives the 

greatest sediment input of the study area (fig. 40). Sedimentaccumulation rates on the Russian River shelf and in Monterey 

Bay (regions 2 and 3, respectively) are significantly lower 

(fig. 40). Elevated rates are also observed in Santa Monica 

Bay (region 6), which are partly related to sediment inputs 

from Transverse Range rivers and the thick accumulation of 

fine sediment in the vicinity of the wastewater outfalls in this 

region (Alexander and Venherm, 2003).

The long-term (>1,000 yr) sediment-accumulation rates 

are generally consistent with recent (<100 yr) rates (fig. 40; 

table 5). Long-term rates should be expected to be somewhat lower than recent rates, owing to infrequent periods of 

accumulation hiatuses and (or) erosion, as discussed by Sadler 

(1999) and Sommerfield (2006). This discrepancy is greatest 

in Santa Monica Bay (region 6), where long-term sedimentaccumulation rates are 5 to 10 times lower than recent rates 

(fig. 40). Although the higher sediment-accumulation rates 

measured during recent years may be related to increases 

in fluvial discharge during the past 100 years (for example, 

Sommerfield and others, 2002), wastewater-outfall inputs 

(especially in some of the samples from Santa Monica Bay), 

or other anthropogenic sources, the longer-term records may 

be stratigraphically incomplete, as described by Sommerfield 

(2006), producing different sediment-accumulation rates over 

different measurement periods. We note that our results for 

Santa Monica Bay (region 6) differ from those of Sommerfield 

(2006), owing to our focus on the shelf and his focus on the 

deeper basins that receive much less sediment.
34 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

0 20 40 60 80 100

0-10

30-40

20-30

10-20

100-110

90-100

80-90

70-80

60-70

50-60

40-50

110-120

0 20 40 60 80 100 0 20 40 60 80 100

A B C

FINE-SEDIMENT CONTENT, IN VOLUME PERCENT

WATER DEPTH, IN METERS

Figure 38. Water depth versus sea-floor-sediment grain size offshore of the Eel River shelf (A), Monterey Bay (B), and offshore of the 

Santa Clara River (C) (figs. 1, 37). Boxes enclose 50 percent of grain-size data within each 10-m depth interval, with median shown as a 

vertical bar within each box. Vertical bars extending from horizontal lines to either side of box indicate maximum and minimum values 

within dataset that fall within an acceptable range, defined as 1.5 times interquartile distance; circles, outliers. Data extracted from 

laboratory analyses reported in usSEABED database (Reid and others, 2006).

Table 5. Regional sediment accumulation rates on the California continental shelf.

[All values in millimeters per year. ND, no data]

Region

(fig. 35)

Inner shelf

(<50-m depth)

Midshelf

(50–100-m depth)

Outer shelf

(>100-m depth)

Long-term

rate

1 13–33(1) 4.2–8(2,3) 1.5–6.4(2,3) 1–5(4)

2 ND 3.7–4.8(2) 1.5–2.4(2,5) ND

3 ND 1–3.9(6) ND 2.2–3.5(7,8,9)

4 ND ND ND ND

5 ND ND 0.5–0.9(10) 0.6–1.2(10,13)

6 1.8–9.7(11) 1–6(11) 0.9–4.9(11) 0.15–0.9(12,13)

7 ND 1–2(14) ND ~3(15)

Notes: 1Crockett and Nittrouer (2004), 2Wheatcroft and Sommerfield (2005), 3Sommerfield and Nittrouer (1999), 4Sommerfield, and others (2002), 5

Demirpolat (1999), 6Lewis and others (2002), 7Greene (1977), 8Mullins and others (1985), 9Chin and others (1988), 10Schwalbach and Gorsline (1985), 11Alexander and Venherm (2003), 12Sommerfield and Lee (2003), 13Sommerfield and Lee (2004), 14Lee and others (2002), 15Hampton and others (2002).
Fate and Accumulation of Fine Sediment 35

A

B

C

0 - 10

10 - 20

20 - 30

30 - 40

40 - 50

50 - 60

60 - 70

70 - 80

80 - 90

90 - 100

Fine-sediment content

(volume percent)

EXPLANATION

Figure 39. Outline maps of California coast (fig. 1) in area of the 

Eel River shelf, showing distribution of fine-sediment content from 

sea-floor-sediment-sampling sites (dots) in usSEABED database 

(Reid and others, 2006) Dynamic characteristic of shelf is evident 

in changes in sediment composition in 1995 (A), 1997 (B), and 1998 

(C). Contour interval, 100 m.
36 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

Figure 40. Regional modern and Holocene sediment-accumulation rates on the California continental shelf in regions 1 through 7 

(fig. 35). ND, no data. See table 5 for data sources.

1 2 3 4 5 6 7

1

2

3

4

5

6

7

8

9

10

0

SEDIMENT-ACCUMULATION RATE, 

IN MILLIMETERS PER YEAR

NDNDNDNDNDNDNDNDNDNDNDND

REGION

Inner shelfMid shelfOuter shelfLong-term rate

13 - 33

EXPLANATION
References Cited 37

Summary

Fine sediment is deposited on the seabed along the 

California coast and forms thick (maximum of tens of meters) 

deposits on the continental shelf (table 5). Fine sediment typically dominates the seabed offshore of large river-sediment 

sources and in midshelf water depths; however, significant 

amounts of fine sediment are observed along the inner shelf, 

where it can represent a significant portion of the fine-sediment budget (for example, ~10 percent of Eel River discharge; 

Crockett and Nittrouer, 2004), especially in southern California, where fine sediment is not subject to strong depth control, 

presumably owing to the lower wave energy of this region.

Sediment-accumulation rates appear to be highest offshore 

of large river-sediment sources, such as the Eel River, and 

consistently higher in shallower water depths. Long-term 

sediment-accumulation rates are generally consistent with 

recent accumulation rates except in southern California, where 

a tenfold discrepancy exists.

Conclusions

The results of this study suggest that large amounts of 

fine sediment are supplied to California coastal waters and 

that the source of this sediment is dominantly coastal rivers. 

Significant spatial and temporal variation exists in the supplies 

of sediment, which are related to the geographic province of 

the watersheds and the intensity of winter storms, respectively. 

The dispersal of sediment occurs primarily as suspended transport related to bottom-wave orbital velocities. This transport 

may be enhanced by downslope gravity flows of fluid mud 

when sufficient amounts of suspended sediment are available. 

Fine sediment has been observed to be initially deposited 

and resuspended during storms over a progression of events 

before final deposition and burial. In fact, most periods when 

waves are able to resuspend fine sediment on the continental 

shelf occur outside of times of river-flood events. Although 

midshelf mud belts are a conspicuous feature of fine-sediment 

accumulation, we note that significant amounts of fine sediment are also deposited and retained on the shelf both inshore 

and offshore of these mud belts. Inner-shelf accumulation of 

sediment appears to be greater in southern California than in 

central or northern California, owing to differences in wave 

climate and, possibly, shelf morphology.

Acknowledgments

This project was supported by the USGS Coastal and 

Marine Geology Program and the California Resources 

Agency under a Coastal Impact Assistance Program grant 

for the California Sediment Master Plan (California Sediment Management Workshop, 2006) being formulated by 

the CSMW and the California Department of Boating and 

Waterways (DBW). The manuscript was prepared with input 

from CSMW personnel but does not necessarily represent the 

official position of member agencies. We thank Patrick Barnard (USGS), Amy Draut (USGS), Clif Davenport (CSMW), 

Mark Johnsson (California Coastal Commission), Homa Lee 

(USGS), Jane Reid (USGS), Arthur Shak (USACE), and Kim 

Sterrett (DBW) for their reviews of the manuscript.

References Cited

Alexander, C.R., and Simoneau, A.M., 1999, Spatial variability in sedimentary processes on the Eel continental slope: 

Marine Geology, v. 154, no. 1–4, p. 243–254.

Alexander, C.R., and Venherm, C., 2003, Modern sedimentary processes in the Santa Monica, California continental 

margin; sediment accumulation, mixing and budget: Marine 

Environmental Research, v. 56, no. 1–2, p. 177–204.

Anchor Environmental CA L.P., 2003, Literature review of 

effects of resuspended sediments due to dredging operations: Los Angeles, Contaminated Sediment Task Force, 87 

p.

Andrews, E.D., Antweiler, R.C., Neiman, P.J., and Ralph, 

F.M., 2004, Influence of ENSO on flood frequency along 

the California coast: Journal of Climate, v. 17, p. 337–348.

Asselman, N.E.M., 2000, Fitting and interpretation of sediment rating curves: Journal of Hydrology, v. 234, no. 3–4, p. 

228–248.

Benumof, B.T., and Griggs, G.B., 1999, The relationships 

between seacliff erosion rates, cliff material properties, and 

physical processes, San Diego, California: Shore and Beach, 

v. 67, no. 4, p. 29–41.

Boggs, S., 1987, Principles of sedimentology and stratigraphy: 

New York, Macmillan, 784 p.

Bruland, K.W., Rue, E.L., and Smith, G.J., 2001, Iron and 

macronutrients in California coastal upwelling regimes; 

implications for diatom blooms: Limnology and Oceanography, v. 46, no. 7, p. 1661–1674.

Buck, K.N., Lohan, M.C., Berger, C.J.M., and Bruland, K.W., 

2007, Dissolved iron speciation in two distinct river plumes 

and an estuary; Implications for riverine iron supply: Limnology and Oceanography, v. 52, no. 2, p. 843–855.

California Department of Boating and Waterways and California Coastal Conservancy, 2002, California beach restoration 

study: Sacramento, California Department of Boating and 

Waterways, 280 p.
38 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

California Coastal Sediment Management Workgroup, 2006, 

Sediment Master Plan Status Report: URL http://www.dbw.

ca.gov/csmw/PDF/SMPSR_status_report.pdf.

Campbell, F.B., and Bauder, H.A., 1940, A rating-curve 

method for determining silt-discharge of streams: Eos 

(American Geophysical Union Transactions), v. 21, p. 

603–607.

Chin, J.L., Clifton, H.E., and Mullins, H.T., 1988, Seismic 

stratigraphy and late Quaternary shelf history, south-central 

Monterey Bay, California: Marine Geology, v. 81, no. 1–4, 

p. 137–157.

Cleveland, W.S., 1979, Robust locally weighted regression and 

smoothing scatterplots: American Statistical Association 

Journal, v. 74, no. 368, p. 829–836.

Crockett, J.S., and Nittrouer, C.A., 2004, The sandy inner 

shelf as a repository for muddy sediment; an example from 

Northern California: Continental Shelf Research, v. 24, no. 

1, p. 55–73.

Curran, K.J., Hill, P.S., and Milligan, T.G., 2002, Fine-grained 

suspended sediment dynamics in the Eel River flood plume: 

Continental Shelf Research, v. 22, no. 17, p. 2537–2550.

Demirpolat, S., 1991, Surface and near-surface sediments from 

the continental shelf off the Russian River, northern California: Marine Geology, v. 99, no. 1–2, p. 163–173.

Drake, D.E., 1972, Distribution and transport of suspended 

matter, Santa Barbara Channel, California: Los Angeles, 

University of Southern California, Ph.D. thesis, 358 p.

Drake, D.E., 1999, Temporal and spatial variability of the 

sediment grain-size distribution on the Eel Shelf; the flood 

layer of 1995: Marine Geology, v. 154, no. 1–4, p. 169–182.

Drake, D.E., and Cacchione, D.A., 1985, Seasonal variation in 

sediment transport on the Russian River shelf, California: 

Continental Shelf Research, v. 4, no. 5, p. 495–514.

Drake, D.E., Eganhouse, R.P., and McArthur, W., 2002, 

Physical and chemical effects of grain aggregates on the 

Palos Verdes margin, southern California: Continental Shelf 

Research, v. 22, no. 6–7, p. 967–986.

Dyer, K.R., 1986, Coastal and estuarine sediment dynamics: 

New York, John Wiley and Sons, 342 p.

Edwards, B.D., 2002, Variations in sediment texture on the 

northern Monterey Bay National Marine Sanctuary continental shelf: Marine Geology, v. 181, no. 1–3, p. 83–100.

Eittreim, S.L., Anima, R., and Stevenson, A.J., 2002a, 

Seafloor geology of the Monterey Bay area continental 

shelf: Marine Geology, v. 181, no. 1–3, p. 3–34.

Eittreim, S.L., Edwards, B.D., and Anima, R.J., 2000, Midshelf mudbelt in northern Monterey Bay [abs.]: Eos (American Geophysical Union Transactions), v. 81, p. 682.

Eittreim, S.L., Xu, J.P., Noble, M., and Edwards, B.D., 2002b, 

Towards a sediment budget for the Santa Cruz shelf: Marine 

Geology, v. 181, no. 1–3, p. 235–248.

Fan, S., Swift, D.J.P., Traykovski, P., Bentley, S., Borgeld, 

J.C., Reed, C.W., and Niedoroda, A.W., 2004, River flooding, storm resuspension, and event stratigraphy on the 

northern California shelf; observations compared with simulations: Marine Geology, v. 210, no. 1–4, p. 17–41.

Ferguson, R.I., 1987, Accuracy and precision of methods for 

estimating river loads: Earth Surface Processes and Landforms, v. 12, no. 1, p. 95–104.

George, D.A., Hill, P.S., and Milligan, T., 2006, Flocculation, 

heavy metals (Cu, Pb, Zn) and the sand-mud transition 

on the Adriatic continental shelf, Italy: Continental Shelf 

Research, v. 27, no. 3–4, p.475–488.

Geyer, W.R., Hill, P., Milligan, T., and Traykovski, P., 2000, 

The structure of the Eel River plume during floods: Continental Shelf Research, v. 20, p. 2067–2093.

Geyer, W.R., Hill, P.S., and Kineke, G.C., 2004, The transport 

and dispersal of sediment by buoyant coastal flows: Continental Shelf Research, v. 27, no. 7–8, p. 927–949.

Greene, H.G., 1977, Geology of the Monterey Bay region: 

U.S. Geological Survey Open-File Report 77–718, 343 p.

Griggs, G.B., and Hein, J.R., 1980, Sources, dispersal, and 

clay mineral composition of fine-grained sediment off central and northern California: Journal of Geology, v. 88, no. 

5, p. 541–566.

Guy, H.P., and Norman, V.W., 1970, Field methods for measurement of fluvial sediment, chap. C2 of Applications of 

hydraulics (book 3): U.S. Geological Survey Techniques of 

Water-Resources Investigation, 59 p.

Hadley, R.F., Lal, E., Onstad, C., Walling, D.E., and Yair, A., 

1985, Recent developments in erosion and sediment yield 

studies: Paris, UNESCO, 127 p.

Hampton, M.A., Karl, H., and Murray, C.J., 2002, Acoustic 

profiles and images of the Palos Verdes Margin; implications concerning deposition from the White’s Point outfall: 

Continental Shelf Research, v. 22, no. 6–7, p. 841–858.

Harris, C.K., Traykovski, P., and Geyer, W.R., 2005, Flood 

dispersal and deposition by near-bed gravitational sediment flows and oceanographic transport; a numerical 

modeling study of the Eel River shelf, northern California: Journal of Geophysical Research, v. 110, no. C9, 

doi:10.1029/2004JC002727.
References Cited 39

Harris, C.K., and Wiberg, P.L., 1997, Approaches to quantifying long-term continental shelf sediment transport with 

an example from the northern California STRESS midshelf site: Continental Shelf Research, v. 17, no. 11, p. 

1389–1418.

Hicks, D.M., Gomez, B., and Trustrum, N.A., 2000, Erosion 

thresholds and suspended sediment yields, Waipaoa River 

Basin, New Zealand: Water Resources Research, v. 36, no. 

4, p. 1129–1142.

Hill, P.S., Milligan, T.G., and Geyer, W.R., 2000, Controls on 

effective settling velocity of suspended sediment in the Eel 

River flood plume: Continental Shelf Research, v. 20, no. 

16, p. 2095–2111.

Hillel, D., 1982, Introduction to soil physics: San Diego, 

Calif., Academic Press, 364 p.

Inman, D.L., and Jenkins, S.A., 1999, Climate change and 

the episodicity of sediment flux of small California rivers: 

Journal of Geology, v. 107, no. 3, p. 251–270.

Inman, D.L., Jenkins, S.A., and Wasyl, J., 1998, Database for 

streamflow and sediment flux of California rivers: Scripps 

Institute of Oceanography Reference Series 98–9, 13 p.

Johnson, K.S., Chavez, F.P., and Friedrich, G.E., 1999, Continental-shelf sediment as a primary source of iron for coastal 

phytoplankton: Nature, v. 398, no. 6729, p. 697–700.

Kirk, J.T.O., 1996, Light and photosynthesis in aquatic ecosystems (2d ed.): Cambridge, U.K., Cambridge University 

Press, 509 p.

Komar, P.D., 1996, The budget of littoral sediments; concepts 

and applications: Shore and Beach, v. 64, no. 3, p. 18–26.

Komar, P.D., 1998, Beach processes and sedimentation (2d 

ed.): Upper Saddle River, N.J., Prentice Hall, 544 p.

Lee, H.J., Sherwood, C.R., Drake, D.E., Edwards, B.D., 

Wong, F.L., and Hamer, M., 2002, Spatial and temporal 

distribution of contaminated, effluent-affected sediment on 

the Palos Verdes margin, southern California: Continental 

Shelf Research, v. 22, no. 6–7, p. 859–880.

Lee, H.J., and Wiberg, P.L., 2002, Character, fate and biological effects of contaminated, effluent-affected sediment on 

the Palos Verdes margin, southern California; an overview: 

Continental Shelf Research, v. 22, no. 6–7, p. 835–840.

Lewis, R.C., Coale, K.H., Edwards, B.D., Marot, M., Douglas, 

J.N., and Burton, E.J., 2002, Accumulation rate and mixing 

of shelf sediments in the Monterey Bay National Marine 

Sanctuary: Marine Geology, v. 181, no. 1–3, p. 157–169.

Mantua, N.J., Haidvogel, D., Kushnir, Y., and Bond, N., 2002, 

Making the climate connections; bridging scales of space 

and time in the U.S. GLOBEC program: Oceanography, v. 

15, no. 2, p. 75–86.

Mantua, N.J., and Hare, S.R., 2002, The Pacific Decadal 

Oscillation: Journal of Oceanography, v. 58, no. 1, p. 35–44.

McCave, I.N., 1972, Transport and escape of fine-grained 

sediment from shelf areas, in Swift, D.J.P., Duane, D., and 

Pilkey, O.H., eds., Shelf sediment transport; process and 

pattern: Stroudsburg, Pa., Dowden, Hutchinson and Ross, p. 

225–248.

McCave, I.N., and Syvitski, J.P.M., 1991, Principles and methods of geological particle size analysis, in Syvitski, J.P.M., 

ed., Principles, methods, and application of particle size 

analysis: New York, Cambridge University Press, p. 3–21.

McCool, W.W., and Parsons, J.D., 2004, Sedimentation 

from buoyant fine-grained suspensions: Continental Shelf 

Research, v. 24, no. 10, p. 1129–1142.

Mertes, L.A.K., and Warrick, J.A., 2001, Measuring flood 

output from 110 coastal watersheds in California with 

field measurements and SeaWiFS: Geology, v. 29, no. 7, p. 

659–662.

Milliman, J.D., and Syvitski, J.P.M., 1992, Geomorphic/tectonic control of sediment discharge to the ocean; the importance of small mountainous rivers: Journal of Geology, v. 

100, no. 5, p. 525–544.

Mulder, T., and Syvitski, J.P.M., 1995, Turbidity currents generated at river mouths during exceptional discharges to the 

world oceans: Journal of Geology, v. 103, no. 3, p. 285–299.

Mullenbach, B.L., Nittrouer, C.A., Puig, P., and Orange, D.L., 

2004, Sediment deposition in a modern submarine canyon; 

Eel Canyon, northern California: Marine Geology, v. 211, 

no. 1–2, p. 101–119.

Mullins, H.T., Nagel, D.K., and Dominguez, L.L., 1985, Tectonic and eustatic controls of late Quaternary shelf sedimentation along the central California (Santa Cruz) continental 

margin; high-resolution seismic stratigraphic evidence: 

Sedimentary Geology, v. 45, no. 3–4, p. 327–347.

Nittrouer, C.A., 1999, STRATAFORM; overview of its design 

and synthesis of its results: Marine Geology, v. 154, no. 

1–4, p. 3–12.

Nittrouer, C.A., and Sternberg, R.W., 1981, The formation of 

sedimentary strata in an allochthonous shelf environment; 

the Washington continental shelf: Marine Geology, v. 42, 

no. 1–4, p. 201–232.
40 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

Nittrouer, C.A., Sternberg, R.W., Carpenter, R., and Bennet, 

J.T., 1979, The use of Pb-210 geochronology as a sedimentological tool; application to the Washington continental 

shelf: Marine Geology, v. 31, no. 3–4, p. 297–316.

Noble, M., Ryan, H.F., and Wiberg, P.L., 2002, The dynamics 

of subtidal poleward flows over a narrow continental shelf, 

Palos Verdes, CA: Continental Shelf Research, v. 22, no. 

6–7, p. 923–944.

Noble, M., and Xu, J.P., 2003, Observations of large-amplitude cross-shore internal bores near the shelf break, Santa 

Monica Bay, CA: Marine Environmental Research, v. 56, 

no. 1–2, p. 127–149.

Ogston, A.S., Cacchione, D.A., Sternberg, R.W., and Kineke, 

G.C., 2000, Observations of storm and river flood-driven 

sediment transport on the northern California continental shelf: Continental Shelf Research, v. 20, no. 16, p. 

2141–2162.

Patsch, K., and Griggs, G.B., 2007, Development of sand budgets for California’s major littoral cells: Santa Cruz, University of California, Institute of Marine Sciences, 115 p.

Pullen, J.D., and Allen, J.S., 2000, Modeling studies of the 

coastal circulation off Northern California; shelf response to 

a major Eel River flood event: Continental Shelf Research, 

v. 20, no. 16, p. 2213–2238.

Rantz, S.E., compiler, 1982, Measurement and computation 

of streamflow: U.S. Geological Survey Water-Supply Paper 

2175, 2 v.

Reid, J.A., Reid, J.M., Jenkins, C.J., Zimmermann, M., Williams, S.J., and Field, M.E., 2006, usSEABED; Pacific coast 

(California, Oregon, and Washington) offshore surficialsediment data release: U.S. Geological Survey Data Series 

182 [URL http://pubs.usgs.gov/ds/2006/182/].

Sadler, P.M., 1999, The influence of hiatuses on sediment 

accumulation rates: GeoResearch Forum, v. 5, p. 15–40.

Schoelhamer, D.H., Lionberger, M.A., Jaffe, B.E., Ganju, 

N.K., Wright, S.A., and Shellenbarger, G.G., 2005, Bay 

sediment budgets; sediment accounting 101, in Pulse of the 

estuary; monitoring and managing water quality in the San 

Francisco Estuary: Oakland, Calif., San Francisco Estuary 

Institute, p. 58–63.

Schwalbach, J.R., and Gorsline, D.S., 1985, Holocene sediment budgets for the basins of the California Continental 

Borderland: Journal of Sedimentary Petrology, v. 55, no. 6, 

p. 829–842.

Scott, K.M., and Williams, R.P., 1978, Erosion and sediment 

yields in the Transverse Ranges, southern California: U.S. 

Geological Survey Professional Paper 1030, 38 p.

Scully, M.E., Friedrichs, C.T., and Wright, L.D., 2002, Application of an analytical model of critically stratified gravitydriven sediment transport and deposition to observations 

from the Eel River continental shelf, Northern California: 

Continental Shelf Research, v. 22, no. 14, p. 1951–1974.

Sherwood, C.R., Drake, D.E., Wiberg, P.L., and Wheatcroft, 

R.A., 2002, Prediction of the fate of p,p′–DDE in sediment 

on the Palos Verdes shelf, California, USA: Continental 

Shelf Research, v. 22, no. 6–7, p. 1025–1058.

Sommerfield, C.K., 2006, On sediment accumulation rates and 

stratigraphic completeness; lessons from Holocene ocean 

margins: Continental Shelf Research, v. 26, p. 2225–2240.

Sommerfield, C.K., Drake, D.E., and Wheatcroft, R.A., 2002, 

Shelf record of climatic changes in flood magnitude and 

frequency, north-coastal California: Geology, v. 30, no. 5, p. 

395–398.

Sommerfield, C.K., and Lee, H.J., 2003, Magnitude and variability of Holocene sediment accumulation in Santa Monica 

Bay, California: Marine Environmental Research, v. 56, no. 

1–2, p. 151–176.

Sommerfield, C.K., and Lee, H.J., 2004, Across-shelf sediment transport since the Last Glacial Maximum, southern 

California margin: Geology, v. 32, no. 4, p. 345–348.

Sommerfield, C.K., and Nittrouer, C.A., 1999, Modern 

accumulation rates and a sediment budget for the Eel River 

shelf; a flood-dominated depositional environment: Marine 

Geology, v. 154, no. 1–4, p. 227–241.

Stanley, D.J., Addy, S.K., and Behrens, E.W., 1983, The 

mudline; variability of its position relative to shelfbreak, in 

Stanley, D.J., and Moore, G.T., eds., The shelfbreak; critical 

interface on continental margins: Tulsa, Okla., Society of 

Economic Paleontologists and Mineralogists Special Publication 33, p. 279–298.

Storlazzi, C.D., and Griggs, G.B., 2000, Influence of El 

Niño-Southern Oscillation (ENSO) events on the evolution of central California’s shoreline: Geological Society of 

America Bulletin, v. 112, no. 2, p. 236–249.

Taylor, J.R., 1997, An introduction to error analysis (2d ed.): 

Sausalito, Calif., University Science Books, 327 p.

Thornton, E.B., Sallenger, A., Sesto, J.C., Egley, L., McGee, 

T., and Parsons, R., 2006, Sand mining impacts on longterm dune erosion in southern Monterey Bay: Marine Geology, v. 229, no. 1–2, p. 45–58.

Traykovski, P., Geyer, W.R., Irish, J.D., and Lynch, J.F., 2000, 

The role of wave-induced density-driven fluid mud flows 

for cross-shelf transport on the Eel River continental shelf: 

Continental Shelf Research, v. 20, no. 16, p. 2113–2140.
References Cited 41

Trimble, S.W., 1997, Contribution of stream channel erosion 

to sediment yield from an urbanizing watershed: Science, v. 

278, no. 21, p. 1442–1444.

Walling, D.E., 1977, Assessing the accuracy of suspended 

sediment rating curves for a small basin: Water Resources 

Research, v. 13, no. 3, p. 531–538.

Walling, D.E., and Moorehead, P.W., 1989, The particle size 

characteristics of fluvial suspended sediment; an overview: 

Hydrobiologia, v. 176–177, no. 1, p. 125–149.

Walling, D.E., and Webb, B.W., 1981, The reliability of suspended sediment load data, in Measurement of erosion and 

transport of sediments: IAHS-AISH Publication, v. 133, p. 

177–194.

Warrick, J.A., Mertes, L.A.K., Washburn, L., and Siegel, D.A., 

2004a, A conceptual model for river water and sediment 

dispersal in the Santa Barbara Channel, California: Continental Shelf Research, v. 24, no. 17, p. 2029–2043.

Warrick, J.A., Mertes, L.A.K., Washburn, L., and Siegel, 

D.A., 2004b, Dispersal forcing of southern California river 

plumes, based on field and remote sensing observations: 

Geo-Marine Letters, v. 24, no. 1, p. 46–52.

Warrick, J.A., and Milliman, J.D., 2003, Hyperpycnal sediment discharge from semiarid southern California rivers; 

implications for coastal sediment budgets: Geology, v. 31, 

no. 9, p. 781–784.

Warrick, J.A., and Rubin, D., 2007, Suspended-sediment rating curve response to urbanization and wildfire, Santa Ana 

River, California: Journal of Geophysical Research, v. 112, 

no. F2, doi:10.1029/2006JF000662.

Wass, P.D., and Leeks, G.J.L., 1999, Suspended sediment 

fluxes in the Humber catchment, UK: Hydrological Processes, v. 13, no. 7, p. 935–953.

Wheatcroft, R.A., and Butman, C.A., 1997, Spatial and 

temporal variability in aggregated grain-size distribution, 

with implications for sediment dynamics: Continental Shelf 

Research, v. 17, no. 4, p. 367–390.

Wheatcroft, R.A., and Sommerfield, C.K., 2005, River sediment flux and shelf sediment accumulation rates on the 

Pacific Northwest margin: Continental Shelf Research, v. 

25, no. 3, p. 311–332.

Wheatcroft, R.A., Sommerfield, C.K., Drake, D.E., Borgeld, 

J.C., and Nittrouer, C.A., 1997, Rapid and widespread dispersal of flood sediment on the Northern California margin: 

Geology, v. 25, no. 2, p. 163–166.

Wiberg, P.L., Drake, D.E., Harris, C.K., and Noble, M., 2002, 

Sediment transport on the Palos Verdes shelf over seasonal 

to decadal time scales: Continental Shelf Research, v. 22, 

no. 6–7, p. 987–1004.

Wiberg, P.L., and Harris, C.K., 2002, Desorption of p,p′–DDE 

from sediment during resuspension events on the Palos 

Verdes shelf, California; a modeling approach: Continental 

Shelf Research, v. 22, no. 6–7, p. 1005–1023.

Willis, C.M., and Griggs, G.B., 2003, Reductions in fluvial 

sediment discharge by coastal dams in California and implications for beach sustainability: Journal of Geology, v. 111, 

no. 2, p. 167–182.

Wright, L.D., and Friedrichs, C.T., 2006, Gravity-driven 

sediment transport on continental shelves; a status report: 

Continental Shelf Research, v. 26, no. 17–18, p. 2092–2107.

Wright, L.D., and Nittrouer, C.A., 1995, Dispersal of river 

sediments in coastal seas; six contrasting cases: Estuaries, v. 

18, no. 3, p. 494–508.

Young, A.P., and Ashford, S.A., 2006, Application of airborne 

LIDAR for seacliff volumetric change and beach sediment 

budget contributions: Journal of Coastal Research, v. 22, no. 

2, p. 307–318.

Yu, B., 2000, A systematic over-estimation of flows: Journal 

of Hydrology, v. 233, no. 1–4, p. 258-262.
42 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

Table A1. Wentworth-Krumbein scale of sediment-size 

classification.

Sediment size Phi (φ) unit Lower-bin

grain diameter (mm)

Boulder −8 256

Cobble −6 64

Pebble −2 4

Granular −1 2

Very coarse sand 0 1

Coarse sand 1 0.5

Medium sand 2 0.25

Fine sand 3 0.125

Very fine sand 4 0.0625

Silt 8 0.004

Clay 12 0.00024

Appendix A. Grain-Size Information

The Wentworth scale divides sediment into size classes based on powers of 2. According to this scale, fine sediment is 

defined as the clay and silt components and includes all particles smaller than 0.0625 mm in diameter (table A1). Krumbein 

introduced the phi (φ) scale as an alternative measure of sediment size, related to grain size by the equation

 φ = −log2 d,

such that d=2−φ, where d is the grain diameter (in millimeters). Thus, larger phi units correspond to smaller grain sizes. The 

phi scale is commonly used throughout the sedimentological community. 
Appendix B. Sediment-Discharge Rating Curves for All Stations 43

Appendix B. Sediment-Discharge Rating Curves for All Stations

The traditional local regression (loess) weighting function is the tricube (fig. B1):

(1 − | x |

3

)

3 for | x | < 1 w(x) = { 0 for | x | ≥ 1.

The estimated suspended-sediment concentration is then obtained by evaluating the local polynomial fit. The entire loess 

fit is complete after the regression-function values have been calculated for each data point. The flexibility in this method is that 

the degree of the polynomial model and the width of the subset window (α, the fraction of the total number of samples) are user 

selectable. For this project, all fits were given a degree of 1 (linear); the weighting factors (α values) of the loess rating curves 

for all the U.S. Geological Survey gaging stations used in this study (fig. 1) are listed in table B1.

Table B1. Weighting factors (α values) of loess sedimentdischarge rating curves for all the U.S. Geological Survey 

gaging stations used in this study, listed from north to south.

[USGS, U.S. Geological Survey]

Watershed

(fig. 1)

USGS

gaging

station

α

value

Smith River 11532500 0.20

Supply Creek 11530020 0.20

Trinity River 11530000 0.20

Klamath River 11523000 0.20

Redwood Creek 11482500 0.20

Mad River 11481000 0.20

Eel River 11477000 0.20

Russian River 11467000 0.20

Pine Creek 11460170 0.40

Pescadero Creek 11162500 0.20

San Lorenzo River 11160500 0.20

Salinas River 11152500 0.20

Carmel River 11143250 0.30

San Jose Creek 11120510 0.40

Ventura River 11118500 0.20

Santa Clara River 11114000 0.30

Calleguas Creek 11106550 0.30

Santa Ana River 11078000 0.30

San Juan Creek 11046550 0.30

San Mateo River 11046370 0.50

Santa Margarita River 11046000 0.40

San Luis Rey River 11042000 0.20

San Dieguito River 11030500 0.40

San Diego River 11022500 0.30

Tijuana River 11013500 0.30

0

5

10

15

20

25

30

SUSPENDED-SEDIMENT CONCENTRATION, 

IN PARTS PER MILLION

0 0.2 0.4 0.6 0.8 1

DISCHARGE, IN CUBIC METERS PER SECOND

0.00

0.17

0.33

0.50

0.67

0.83

1.00

WEIGHT

A

B

All data

Window data

Estimated point

Weighting

EXPLANATION

Figure B1. Example of loess rating-curve weighting function. A, 

Weighting function on outer edges of data, showing truncation of 

curve. B, Full weighting function for locally weighted regression.
44 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

Figure B2. Loess rating curves of suspended-sediment concentration versus discharge for watersheds used in this study (fig. 1). Top, 

instantaneous measured (green curve, left) and daily-reported (red curve, center) suspended-sediment concentration (in parts per 

million) versus discharge (in cubic meters per second), with a combined plot (right) of both datasets for comparison. Middle, vertically 

compressed plots of top two curves, with ±2σ deviations of daily-reported suspended-sediment concentration (blue curves) added for 

reference. Bottom, residual analyses of weighted-least-squares fits to curves in middle plots. 

A, Smith River (U.S. Geological Survey gaging sta. 11532500). 

B, Supply Creek (U.S. Geological Survey gaging sta. 11530020). 

C, Trinity River (U.S. Geological Survey gaging sta. 11530000). 

D, Klamath River (U.S. Geological Survey gaging sta. 11523000). 

E, Redwood Creek (U.S. Geological Survey gaging sta. 11482500). 

F, Mad River (U.S. Geological Survey gaging sta. 11481000). 

G, Eel River (U.S. Geological Survey gaging sta. 11477000). 

H, Russian River (U.S. Geological Survey gaging sta. 11467000). 

I, Pine Creek (U.S. Geological Survey gaging sta. 11460170). 

J, Pescadero Creek (U.S. Geological Survey gaging sta. 11162500). 

K, San Lorenzo River (U.S. Geological Survey gaging sta. 11160500). 

L, Salinas River (U.S. Geological Survey gaging sta. 11152500). 

M, Carmel River (U.S. Geological Survey gaging sta. 11143250). 

N, San Jose Creek (U.S. Geological Survey gaging sta. 11120510). 

O, Ventura River (U.S. Geological Survey gaging sta. 11118500). 

P, Santa Clara River (U.S. Geological Survey gaging sta. 11114000). 

Q, Calleguas Creek (U.S. Geological Survey gaging sta. 11106550). 

R, Santa Ana River (U.S. Geological Survey gaging sta. 11078000). 

S, San Juan Creek (U.S. Geological Survey gaging sta. 11046550). 

T, San Mateo River (U.S. Geological Survey gaging sta. 11046370). 

U, Santa Margarita River (U.S. Geological Survey gaging sta. 11046000). 

V, San Luis Rey River (U.S. Geological Survey gaging sta. 11042000). 

W, San Dieguito River (U.S. Geological Survey gaging sta. 11030500). 

X, San Diego River (U.S. Geological Survey gaging sta. 11022500). 

Y, Tijuana River (U.S. Geological Survey gaging sta. 11013500).
Appendix B. Sediment-Discharge Rating Curves for All Stations 45

Figure B2. A, Smith River (U.S. Geological Survey gaging sta. 11532500).

0 1 2 3 4 0

0.5

1

1.5

2

2.5

3

n=91

0 1 2 3 4 0 1 2 3 4

11532500

Instantaneous

11532500

Daily

2

11532500

Instant–Daily Compare

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

0 1 2 3 4 0

0.5

1

1.5

2

2.5

3

0 1 2 3 4

–0.8

–0.6

–0.4

–0.2

0

0.2

0.4

0.6

0.8

0 1 2 3 4

0 1 2 3 4

11532500

Instant Loess–Fit

11532500

Residuals for Instant Loess–Fit

11532500

Daily Loess–Fit

11532500

Residuals for Daily Loess–Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE LOGARITHM OF CONCENTRATION RESIDUALS
46 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

−1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11530020

Instantaneous

n=121

−1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11530020

Daily

−1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11530020

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

−1 −0.5 0 0.5 1 1.5 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11530020

Instant Loess−Fit

−1 −0.5 0 0.5 1 1.5 2

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

11530020

Residuals for Instant Loess−Fit

−1 −0.5 0 0.5 1 1.5 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11530020

Daily Loess−Fit

−1 −0.5 0 0.5 1 1.5 2

−1.5

−1

−0.5

0

0.5

1

1.5

11530020

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE LOGARITHM OF CONCENTRATION RESIDUALS

Figure B2 B, Supply Creek (U.S. Geological Survey gaging sta. 11530020)—Continued.
Appendix B. Sediment-Discharge Rating Curves for All Stations 47

0 1 2 3 4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11530000

Instantaneous

n=244

0 1 2 3 4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11530000

Daily

0 1 2 3 4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11530000

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

0 1 2 3 4 0

1

2

3

4

5

11530000

Instant Loess−Fit

0 1 2 3 4

−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

11530000

Residuals for Instant Loess−Fit

0 1 2 3 4 0

1

2

3

4

5

11530000

Daily Loess−Fit

0 1 2 3 4

−1.5

−1

−0.5

0

0.5

1

1.5

11530000

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS

Figure B2 C, Trinity River (U.S. Geological Survey gaging sta. 11530000)—Continued.
48 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

1 2 3 4 0

0.5

1

1.5

2

2.5

3

3.5

4

11523000

Instantaneous

n=140

1 2 3 4 0

0.5

1

1.5

2

2.5

3

3.5

4

11523000

Daily

1 2 3 4 0

0.5

1

1.5

2

2.5

3

3.5

4

11523000

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

1 1.5 2 2.5 3 3.5 4 0

0.5

1

1.5

2

2.5

3

3.5

4

11523000

Instant Loess−Fit

1 1.5 2 2.5 3 3.5 4

−1

−0.5

0

0.5

1

11523000

Residuals for Instant Loess−Fit

1 1.5 2 2.5 3 3.5 4 0

0.5

1

1.5

2

2.5

3

3.5

4

11523000

Daily Loess−Fit

1 1.5 2 2.5 3 3.5 4

−1.5

−1

−0.5

0

0.5

1

1.5

11523000

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS

Figure B2 D, Klamath River (U.S. Geological Survey gaging sta. 11523000)—Continued.
Appendix B. Sediment-Discharge Rating Curves for All Stations 49

−2 0 2 4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11482500

Instantaneous

n=366

−2 0 2 4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11482500

Daily

−2 0 2 4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11482500

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 E, Redwood Creek (U.S. Geological Survey gaging sta. 11482500)—Continued.

−2 −1 0 1 2 3 4 0

1

2

3

4

5

11482500

Instant Loess−Fit

−2 −1 0 1 2 3 4

−1.5

−1

−0.5

0

0.5

1

1.5

11482500

Residuals for Instant Loess−Fit

−2 −1 0 1 2 3 4 0

1

2

3

4

5

11482500

Daily Loess−Fit

−2 −1 0 1 2 3 4

−2

−1.5

−1

−0.5

0

0.5

1

1.5

2

11482500

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
50 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

−2 0 2 4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11481000

Instantaneous

n=102

−2 0 2 4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11481000

Daily

−2 0 2

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11481000

Instant−Daily Compare

Figure B2 F, Mad River (U.S. Geological Survey gaging sta. 11481000)—Continued.

−2 −1 0 1 2 3 4 0

1

2

3

4

5

11481000

Instant Loess−Fit

−2 −1 0 1 2 3 4

−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

11481000

Residuals for Instant Loess−Fit

−2 −1 0 1 2 3 4 0

1

2

3

4

5

11481000

Daily Loess−Fit

−2 −1 0 1 2 3 4

−1.5

−1

−0.5

0

0.5

1

1.5

11481000

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
Appendix B. Sediment-Discharge Rating Curves for All Stations 51

−1 0 1 2 3 4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11477000

Instantaneous

n=210

−1 0 1 2 3 4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11477000

Daily

−1 0 1 2 3 4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11477000

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 G, Eel River (U.S. Geological Survey gaging sta. 11477000)—Continued.

−1 0 1 2 3 4 0

1

2

3

4

5

11477000

Instant Loess−Fit

−1 0 1 2 3 4

−1

−0.5

0

0.5

1

11477000

Residuals for Instant Loess−Fit

−1 0 1 2 3 4 0

1

2

3

4

5

11477000

Daily Loess−Fit

−1 0 1 2 3 4

−2

−1.5

−1

−0.5

0

0.5

1

1.5

2

11477000

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
52 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

−2 0 2 4 0

0.5

1

1.5

2

2.5

3

3.5

4

11467000

Instantaneous

n=992

−2 0 2 4 0

0.5

1

1.5

2

2.5

3

3.5

4

11467000

Daily

−2 0 2 4 0

0.5

1

1.5

2

2.5

3

3.5

4

11467000

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 H, Russian River (U.S. Geological Survey gaging sta. 11467000)—Continued.

−2 −1 0 1 2 3 4 0

0.5

1

1.5

2

2.5

3

3.5

4

11467000

Instant Loess−Fit

−2 −1 0 1 2 3 4

−1.5

−1

−0.5

0

0.5

1

1.5

11467000

Residuals for Instant Loess−Fit

−2 −1 0 1 2 3 4 0

0.5

1

1.5

2

2.5

3

3.5

4

11467000

Daily Loess−Fit

−2 −1 0 1 2 3 4

−2

−1.5

−1

−0.5

0

0.5

1

1.5

2

11467000

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
Appendix B. Sediment-Discharge Rating Curves for All Stations 53

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11460170

Instantaneous

n=34

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11460170

Daily

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11460170

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 I, Pine Creek (U.S. Geological Survey gaging sta. 11460170)—Continued.

−4 −3 −2 −1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11460170

Instant Loess−Fit

−4 −3 −2 −1 0 1 2 −0.6

−0.4

−0.2

0

0.2

0.4

0.6

11460170

Residuals for Instant Loess−Fit

−4 −3 −2 −1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11460170

Daily Loess−Fit

−4 −3 −2 −1 0 1 2

−1

−0.5

0

0.5

1

11460170

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
54 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

−2 −1 0 1 2 3 0

0.5

1

1.5

2

2.5

3

3.5

4

11162500

Instantaneous

n=57

−2 −1 0 1 2 3 0

0.5

1

1.5

2

2.5

3

3.5

4

11162500

Daily

−2 −1 0 1 2 3 0

0.5

1

1.5

2

2.5

3

3.5

4

11162500

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 J, Pescadero Creek (U.S. Geological Survey gaging sta. 11162500)—Continued.

−2 −1 0 1 2 3 0

0.5

1

1.5

2

2.5

3

3.5

4

11162500

Instant Loess−Fit

−2 −1 0 1 2 3

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

11162500

Residuals for Instant Loess−Fit

−2 −1 0 1 2 3 0

0.5

1

1.5

2

2.5

3

3.5

4

11162500

Daily Loess−Fit

−2 −1 0 1 2 3

−1

−0.5

0

0.5

1

11162500

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
Appendix B. Sediment-Discharge Rating Curves for All Stations 55

−1 0 1 2 3 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11160500

Instantaneous

n=142

−1 0 1 2 3 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11160500

Daily

−1 0 1 2 3 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11160500

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 K, San Lorenzo River (U.S. Geological Survey gaging sta. 11160500)—Continued.

−1 0 1 2 3 0

1

2

3

4

5

11160500

Instant Loess−Fit

−1 0 1 2 3

−1

−0.5

0

0.5

1

11160500

Residuals for Instant Loess−Fit

−1 0 1 2 3 0

1

2

3

4

5

11160500

Daily Loess−Fit

−1 0 1 2 3

−1.5

−1

−0.5

0

0.5

1

1.5

11160500

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
56 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

−2 0 2 4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11152500

Instantaneous

n=108

−2 0 2 4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11152500

Daily

−2 0 2 4 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11152500

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 , Salinas River (U.S. Geological Survey gaging sta. 11152500)—Continued.

−3 −2 −1 0 1 2 3 4 0

1

2

3

4

5

11152500

Instant Loess−Fit

−3 −2 −1 0 1 2 3 4

−1

−0.5

0

0.5

1

11152500

Residuals for Instant Loess−Fit

−3 −2 −1 0 1 2 3 4 0

1

2

3

4

5

11152500

Daily Loess−Fit

−3 −2 −1 0 1 2 3 4

−1.5

−1

−0.5

0

0.5

1

1.5

11152500

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
Appendix B. Sediment-Discharge Rating Curves for All Stations 57

−1 0 1 2 3 0

0.5

1

1.5

2

2.5

3

3.5

4

11143250

Instantaneous

n=35

−1 0 1 2 3 0

0.5

1

1.5

2

2.5

3

3.5

4

11143250

Daily

−1 0 1 2 3 0

0.5

1

1.5

2

2.5

3

3.5

4

11143250

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 M, Carmel River (U.S. Geological Survey gaging sta. 11143250)—Continued.

−1 0 1 2 3 0

0.5

1

1.5

2

2.5

3

3.5

4

11143250

Instant Loess−Fit

−1 0 1 2 3

−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

11143250

Residuals for Instant Loess−Fit

−1 0 1 2 3 0

0.5

1

1.5

2

2.5

3

3.5

4

11143250

Daily Loess−Fit

−1 0 1 2 3

−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

11143250

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
58 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11120510

Instantaneous

n=21

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11120510

Daily

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11120510

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 N, San Jose Creek (U.S. Geological Survey gaging sta. 11120510)—Continued.

−4 −3 −2 −1 0 1 2 0

1

2

3

4

5

11120510

Instant Loess−Fit

−4 −3 −2 −1 0 1 2

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

11120510

Residuals for Instant Loess−Fit

−4 −3 −2 −1 0 1 2 0

1

2

3

4

5

11120510

Daily Loess−Fit

−4 −3 −2 −1 0 1 2

−3

−2

−1

0

1

2

3

11120510

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
Appendix B. Sediment-Discharge Rating Curves for All Stations 59

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11118500

Instantaneous

n=220

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11118500

Daily

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11118500

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 O, Ventura River (U.S. Geological Survey gaging sta. 11118500)—Continued.

−4 −3 −2 −1 0 1 2 3 0

1

2

3

4

5

11118500

Instant Loess−Fit

−4 −3 −2 −1 0 1 2 3

−2

−1.5

−1

−0.5

0

0.5

1

1.5

2

11118500

Residuals for Instant Loess−Fit

−4 −3 −2 −1 0 1 2 3 0

1

2

3

4

5

11118500

Daily Loess−Fit

−4 −3 −2 −1 0 1 2 3

−1.5

−1

−0.5

0

0.5

1

1.5

11118500

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
60 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

−4 −2 0 2 4 0

1

2

3

4

5

6

11114000

Instantaneous

n=194

−4 −2 0 2 4 0

1

2

3

4

5

6

11114000

Daily

−4 −2 0 2 4 0

1

2

3

4

5

6

11114000

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 P, Santa Clara River (U.S. Geological Survey gaging sta. 11114000)—Continued.

−4 −2 0 2 4 0

1

2

3

4

5

6

11114000

Instant Loess−Fit

−4 −2 0 2 4

−2

−1

0

1

2

11114000

Residuals for Instant Loess−Fit

−4 −2 0 2 4 0

1

2

3

4

5

6

11114000

Daily Loess−Fit

−4 −2 0 2 4

−3

−2

−1

0

1

2

3

11114000

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
Appendix B. Sediment-Discharge Rating Curves for All Stations 61

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11106550

Instantaneous

n=94

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11106550

Daily

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11106550

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 Q, Calleguas Creek (U.S. Geological Survey gaging sta. 11106550)—Continued.

−4 −3 −2 −1 0 1 2 3 0

1

2

3

4

5

11106550

Instant Loess−Fit

−4 −3 −2 −1 0 1 2 3

−1

−0.5

0

0.5

1

11106550

Residuals for Instant Loess−Fit

−4 −3 −2 −1 0 1 2 3 0

1

2

3

4

5

11106550

Daily Loess−Fit

−4 −3 −2 −1 0 1 2 3

−2

−1.5

−1

−0.5

0

0.5

1

1.5

2

11106550

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
62 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11078000

Instantaneous

n=217

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11078000

Daily

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11078000

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 R, Santa Ana River (U.S. Geological Survey gaging sta. 11078000)—Continued.

−4 −3 −2 −1 0 1 2 3 0

1

2

3

4

5

11078000

Instant Loess−Fit

−4 −3 −2 −1 0 1 2 3

−1

−0.5

0

0.5

1

11078000

Residuals for Instant Loess−Fit

−4 −3 −2 −1 0 1 2 3 0

1

2

3

4

5

11078000

Daily Loess−Fit

−4 −3 −2 −1 0 1 2 3

−1.5

−1

−0.5

0

0.5

1

1.5

11078000

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
Appendix B. Sediment-Discharge Rating Curves for All Stations 63

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11046550

Instantaneous

n=105

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11046550

Daily

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11046550

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 S, San Juan Creek (U.S. Geological Survey gaging sta. 11046550)—Continued.

−4 −3 −2 −1 0 1 2 3 0

1

2

3

4

5

11046550

Instant Loess−Fit

−4 −3 −2 −1 0 1 2 3

−1

−0.5

0

0.5

1

11046550

Residuals for Instant Loess−Fit

−4 −3 −2 −1 0 1 2 3 0

1

2

3

4

5

11046550

Daily Loess−Fit

−4 −3 −2 −1 0 1 2 3

−2

−1.5

−1

−0.5

0

0.5

1

1.5

2

11046550

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
64 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

−2 −1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11046370

Instantaneous

n=12

−2 −1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11046370

Daily

−2 −1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11046370

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 T, San Mateo River (U.S. Geological Survey gaging sta. 11046370)—Continued.

−2 −1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11046370

Instant Loess−Fit

−2 −1 0 1 2

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

11046370

Residuals for Instant Loess−Fit

−2 −1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11046370

Daily Loess−Fit

−2 −1 0 1 2 −1

−0.5

0

0.5

1

11046370

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
Appendix B. Sediment-Discharge Rating Curves for All Stations 65

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11046000

Instantaneous

n=22

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11046000

Daily

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11046000

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 U, Santa Margarita River (U.S. Geological Survey gaging sta. 11046000)—Continued.

−4 −3 −2 −1 0 1 2 3 0

1

2

3

4

5

11046000

Instant Loess−Fit

−4 −3 −2 −1 0 1 2 3

−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

11046000

Residuals for Instant Loess−Fit

−4 −3 −2 −1 0 1 2 3 0

1

2

3

4

5

11046000

Daily Loess−Fit

−4 −3 −2 −1 0 1 2 3

−1

−0.5

0

0.5

1

11046000

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
66 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

−2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11042000

Instantaneous

n=249

−2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11042000

Daily

−2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

11042000

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 V, San Luis Rey River (U.S. Geological Survey gaging sta. 11042000)—Continued.

−3 −2 −1 0 1 2 3 0

1

2

3

4

5

11042000

Instant Loess−Fit

−3 −2 −1 0 1 2 3

−1.5

−1

−0.5

0

0.5

1

1.5

11042000

Residuals for Instant Loess−Fit

−3 −2 −1 0 1 2 3 0

1

2

3

4

5

11042000

Daily Loess−Fit

−3 −2 −1 0 1 2 3

−3

−2

−1

0

1

2

3

11042000

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
Appendix B. Sediment-Discharge Rating Curves for All Stations 67

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11030500

Instantaneous

n=40

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11030500

Daily

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11030500

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 W, San Dieguito River (U.S. Geological Survey gaging sta. 11030500)—Continued.

−4 −3 −2 −1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11030500

Instant Loess−Fit

−4 −3 −2 −1 0 1 2

−1

−0.5

0

0.5

1

11030500

Residuals for Instant Loess−Fit

−4 −3 −2 −1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11030500

Daily Loess−Fit

−4 −3 −2 −1 0 1 2

−1.5

−1

−0.5

0

0.5

1

1.5

11030500

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
68 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11022500

Instantaneous

n=43

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11022500

Daily

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11022500

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 X, San Diego River (U.S. Geological Survey gaging sta. 11022500)—Continued.

−4 −3 −2 −1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11022500

Instant Loess−Fit

−4 −3 −2 −1 0 1 2

−0.4

−0.3

−0.2

−0.1

0

0.1

0.2

0.3

0.4

11022500

Residuals for Instant Loess−Fit

−4 −3 −2 −1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11022500

Daily Loess−Fit

−4 −3 −2 −1 0 1 2

−0.8

−0.6

−0.4

−0.2

0

0.2

0.4

0.6

0.8

11022500

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
Appendix B. Sediment-Discharge Rating Curves for All Stations 69

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11013500

Instantaneous

n=20

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11013500

Daily

−4 −2 0 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11013500

Instant−Daily Compare

LOGARITHM OF DISCHARGE

LOGARITHM OF SUSPENDED SEDIMENT CONCENTRATION

LOGARITHM OF DISCHARGE LOGARITHM OF DISCHARGE

Figure B2 Y, Tijuana River (U.S. Geological Survey gaging sta. 11013500)—Continued.

−4 −3 −2 −1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11013500

Instant Loess−Fit

−4 −3 −2 −1 0 1 2

−0.4

−0.3

−0.2

−0.1

0

0.1

0.2

0.3

0.4

11013500

Residuals for Instant Loess−Fit

−4 −3 −2 −1 0 1 2 0

0.5

1

1.5

2

2.5

3

3.5

4

11013500

Daily Loess−Fit

−4 −3 −2 −1 0 1 2

−3

−2

−1

0

1

2

3

11013500

Residuals for Daily Loess Fits

LOGARITHM OF CONCENTRATION

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

RESIDUALS

LOGARITHM OF DISCHARGE

LOGARITHM OF DISCHARGE

LOGARITHM OF CONCENTRATION RESIDUALS
70 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

Appendix C. Fine-Sediment-Fraction/Discharge Curves for All Stations

This appendix presents plots of the fine-sediment-fraction/discharge relation for data from all the U.S. Geological Survey 

gaging stations used in this study (fig. 1). Weighting factors (α values) of the loess rating curves are listed in table C1.

Table C1. Weighting factors (α values) of loess fine-sedimentfraction/discharge rating curves for all the U.S. Geological 

Survey gaging stations used in this study, listed from north to 

south.

[USGS, U.S. Geological Survey]

Watershed

(fig. 1)

USGS

gaging

station

α

value

Smith River 11532500 0.3

Supply Creek 11530020 0.3

Trinity River 11530000 0.3

Klamath River 11523000 0.3

Redwood Creek 11482500 0.3

Mad River 11481000 0.3

Eel River 11477000 0.3

Russian River 11467000 0.3

Pine Creek 11460170 0.3

Pescadero Creek 11162500 0.3

San Lorenzo River 11160500 0.3

Salinas River 11152500 0.3

Carmel River 11143250 0.3

San Jose Creek 11120510 0.3

Ventura River 11118500 0.3

Santa Clara River 11114000 0.3

Calleguas Creek 11106550 0.3

Santa Ana River 11078000 0.3

San Juan Creek 11046550 0.3

San Mateo River 11046370 0.4

Santa Margarita River 11046000 0.3

San Luis Rey River 11042000 0.3

San Dieguito River 11030500 0.5

San Diego River 11022500 0.3

Tijuana River 11013500 0.4

Figure C1. Loess rating curves (black) of fine-sediment content 

versus discharge for watersheds used in this study (fig. 1), with 

±2σ deviations (red curves) shown for reference.

A, Smith River (U.S. Geological Survey gaging sta. 11532500).

B, Supply Creek (U.S. Geological Survey gaging sta. 11530020). 

C, Trinity River (U.S. Geological Survey gaging sta. 11530000). 

D, Klamath River (U.S. Geological Survey gaging sta. 11523000). 

E, Redwood Creek (U.S. Geological Survey gaging sta. 11482500). 

F, Mad River (U.S. Geological Survey gaging sta. 11481000). 

G, Eel River (U.S. Geological Survey gaging sta. 11477000). 

H, Russian River (U.S. Geological Survey gaging sta. 11467000). 

I, Pine Creek (U.S. Geological Survey gaging sta. 11460170). 

J, Pescadero Creek (U.S. Geological Survey gaging sta. 11162500). 

K, San Lorenzo River (U.S. Geological Survey gaging 

sta. 11160500). 

L, Salinas River (U.S. Geological Survey gaging sta. 11152500). 

M, Carmel River (U.S. Geological Survey gaging sta. 11143250). 

N, San Jose Creek (U.S. Geological Survey gaging sta. 11120510). 

O, Ventura River (U.S. Geological Survey gaging sta. 11118500). 

P, Santa Clara River (U.S. Geological Survey gaging sta. 11114000). 

Q, Calleguas Creek (U.S. Geological Survey gaging sta. 11106550).

R, Santa Ana River (U.S. Geological Survey gaging sta. 11078000). 

S, San Juan Creek (U.S. Geological Survey gaging sta. 11046550). 

T, San Mateo River (U.S. Geological Survey gaging sta. 11046370). 

U, Santa Margarita River (U.S. Geological Survey gaging sta. 

11046000). 

V, San Luis Rey River (U.S. Geological Survey gaging sta. 

11042000). 

W, San Dieguito River (U.S. Geological Survey gaging sta. 

11030500). 

X, San Diego River (U.S. Geological Survey gaging sta. 11022500). 

Y, Tijuana River (U.S. Geological Survey gaging sta. 11013500).
Appendix C. Fine-Sediment-Fraction/Discharge Curves for All Stations 71

0 500 1000 1500 2000 2500 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

11532500 A Fit to Grainsize

0 5 10 15 20 25 30 35 40 45 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11530020

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

B

0 500 1000 1500 2000 2500 3000 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11530000

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

C

0 1000 2000 3000 4000 5000 6000 7000 8000

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

11523000 D Fit to Grainsize

0 500 1000 1500 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11482500

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

E

Figure C1.

0 200 400 600 800 1000 1200 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11481000

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

F
72 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

0 2000 4000 6000 8000 10000 12000 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11477000

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

G

0 500 1000 1500 2000 2500 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11467000

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

H

0 1 2 3 4 5 6 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11460170

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

I

0 20 40 60 80 100 120 140 160 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11162500

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

J

0 50 100 150 200 250 300 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11160500

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

K

Figure C1—Continued.

0 100 200 300 400 500 600 700 800 900 1000 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11152500

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

L
Appendix C. Fine-Sediment-Fraction/Discharge Curves for All Stations 73

0 50 100 150 200 250 300 350 400 450 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11143250

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

M

0 2 4 6 8 10 12 14 16 18 20 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11120510

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

N

0 50 100 150 200 250 300 350 400 450 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11118500

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

O

0 500 1000 1500 2000 2500 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11114000

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

P

0 50 100 150 200 250 300 350 400 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11106550

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

Q

Figure C1—Continued.

0 50 100 150 200 250 300 350 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11078000

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

R
74 Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California

0 50 100 150 200 250 300 350 400 450 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11046550

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

S

0 5 10 15 20 25 30 35 40 45 50 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11046370

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

T

0 20 40 60 80 100 120 140 160 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11046000

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

U

0 50 100 150 200 250 300 350 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11042000

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

V

Figure C1—Continued.

0 5 10 15 20 25 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11030500

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

W

0 5 10 15 20 25 30 35 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11022500

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

X
Appendix C. Fine-Sediment-Fraction/Discharge Curves for All Stations 75

0 10 20 30 40 50 60 70 0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

11013500

 Fit to Grainsize

DISCHARGE, IN CUBIC METERS PER SECOND

 FINE-GRAINED SEDIMENT CONTENT, IN VOLUME PERCENT

Y

Figure C1—Continued.
Appendix D. Fine-Sediment Contributions to Coastal California from Coastal Cliffs and Bl

This appendix presents calculations of the fine-sediment contributions from erosion of coastal cliffs and bluffs in southern California litt

Patsch and Griggs, 2005). Table D1. Fine-sediment input from cliffs and bluffs into various sections of the California coast—Continued. [Data on length, height, sand content, and erosion rate for Oceanside and Santa Barbara segments from California Department of Boating and Waterways and California Coast

other segments from Patsch and Griggs (2005). Mud content is the left over fraction of sediment, calculated as 100 volume percent minus sand content. Input from bluffs is calmeters) × (Height of bedrock, in meters) × (Mud fraction) × (Erosion rate, in meters per year), and from terraces as (Length of cliff, in meters) × (Height of terrace, in meters) rate, in meters per year). Total input is the sum of bluff/cliff and terrace input] Segment Length (m) Bedrock Terrace Erosion rate (m/yr) Input 

bedr

(m3/

Height

(m)

Sand

content

(vol pct)

Mud

content

(vol pct)

Height

(m)

Sand

content

(vol pct)

Mud

content

(vol pct)

Mission Bay

Point La Jolla-Calumet Park 5,546 3 39.51 60.49 4 88.12 11.88 0.40 4,02

Calumet Park-Mission Bay 527 9 39.51 60.49 3 88.12 11.88 0.40 1,14Ocean Beach Fishing Pier-City Beach 187 4 39.51 60.49 6 88.12 11.88 0.40 18Ocean Beach City Beach-Sunset Cliffs Park 1,747 9 39.51 60.49 3 88.12 11.88 0.40 5,70Sunset Cliffs-Point Loma 7,388 30 39.51 60.49 0 88.12 11.88 0.40 80,44Total 

Oceanside

Scripps Pier-Torrey Pines 6,832 28 51.1 48.9 3.4 57.4 42.6 0.15 14,03Torrey Pines-Del Mar 2,556 7.7 51.1 48.9 3.4 57.4 42.6 0.12 1,15Del Mar-Solana Beach 2,858 8 51.1 48.9 3.9 57.4 42.6 0.1 1,11Cardiff by the Sea-San Elijo State Park 1,346 4.6 51.1 48.9 6.2 57.4 42.6 0.1 30San Elijo-Encinitas 1,179 14.1 51.1 48.9 2.8 57.4 42.6 0.1 81Moonlight State Beach-Leucadia 3,858 9.9 51.1 48.9 3.7 57.4 42.6 0.2 3,73Leucadia-Carlsbad Army and Navy 8,047 3.1 51.1 48.9 4.3 57.4 42.6 0.15 1,82Camp Pendleton-San Onofre 19,680 7.3 51.1 48.9 0.5 57.4 42.6 0.15 10,53San Mateo Point-Dana Point 5,767 13.2 51.1 48.9 2.3 57.4 42.6 0.15 5,58Total 

Laguna

Newport Bay-Little Corona Del Mar Beach 1,726 12 33.09 66.91 2 81.63 18.37 0.06 84Little Corona Del Mar-Crystal Cove State Park 74,550 0 0 100 0 0 100 0.06 Crystal Cove-Heisler Park 6,926 18 33.09 66.91 3 81.63 18.37 0.06 5,08Heisler Park-Southern Laguna Beaches 2,397 8 33.09 66.91 2 81.63 18.37 0.06 78Southern Laguna Beaches-Ruby Street Park 438 11 33.09 66.91 2 81.63 18.37 0.06 19Ruby Street Park-Aliso Beach 2,397 5 33.09 66.91 2 81.63 18.37 0.06 48Aliso Beach-Camel Point 791 8 33.09 66.91 3 81.63 18.37 0.06 25Camel Point-Thousand Steps 1,042 14 33.09 66.91 2 81.63 18.37 0.06 59Thousand Steps-Salt Creek Beech Park 2,144 17 33.09 66.91 5 88.12 11.88 0.40 8,81Total 

Table D1. Fine-sediment input from cliffs and bluffs into various sections of the California coast.[Data on length, height, sand content, and erosion rate for Oceanside and Santa Barbara segments from California Department of Boating and Waterways and California Coastother segments from Patsch and Griggs (2005). Mud content is the left over fraction of sediment, calculated as 100 volume percent minus sand content. Input from bluffs is calmeters) × (Height of bedrock, in meters) × (Mud fraction) × (Erosion rate, in meters per year), and from terraces as (Length of cliff, in meters) × (Height of terrace, in meters) rate, in meters per year). Total input is the sum of bluff/cliff and terrace input]
Table D1. Fine-sediment input from cliffs and bluffs into various sections of the California coast—Continued.[Data on length, height, sand content, and erosion rate for Oceanside and Santa Barbara segments from California Department of Boating and Waterways and California Coastother segments from Patsch and Griggs (2005). Mud content is the left over fraction of sediment, calculated as 100 volume percent minus sand content. Input from bluffs is calmeters) × (Height of bedrock, in meters) × (Mud fraction) × (Erosion rate, in meters per year), and from terraces as (Length of cliff, in meters) × (Height of terrace, in meters) rate, in meters per year). Total input is the sum of bluff/cliff and terrace input]

San Pedro

Point Vincent-Point Fermin 12,330 30 42.02 57.98 0 – – – – 0.305 65,41

Anaheim-Bolsa Chica State Park 1,160 30 14.24 85.76 0 – – – – 0.305 9,10Total 

Santa Monica

Point Mugu-Point Dume 9,091 15 23.04 76.96 2 88.84 11.16 0.15 15,99Point Dume-Paradise Cove 3,207 12 23.04 76.96 0 88.84 11.16 0.15 4,51Paradise Cove-King Harbor 3,652 15 23.04 76.96 2 88.84 11.16 0.15 6,42Dockweiler State Beach-Hermosa City Beach 1,487 11 23.04 76.96 2 88.84 11.16 0.15 1,91King Harbor-Torrance County Beach 2,451 11 23.04 76.96 2 88.84 11.16 0.15 3,16

Malaga Cove-Palos Verdes Estates Shoreline Preserve 7,955 91 23.04 76.96 5 88.84 11.16 0.51 283,65

Total 

Santa Barbara

Rincon Point-Loon Point 5,540 30 0.1 99.9 0.5 60 40 0.305 50,64Loon Point-Fernald Point 2,934 21 0.1 99.9 1.7 60 40 0.305 18,77Fernald Point-Santa Barbara Cemetery 1,350 29 0.1 99.9 0.1 60 40 0.305 11,92Santa Barbara Point-Lighthouse 2,080 14 0.1 99.9 3 60 40 0.152 4,42Lighthouse-Arroyo Burro 1,995 14.3 0.1 99.9 4 60 40 0.152 4,33Arroyo Burro-Hope Ranch 4,200 13.7 0.1 99.9 0.5 60 40 0.152 8,73Goleta Beach-Goleta Point 1,600 6.5 0.1 99.9 3.5 60 40 0.305 3,16Goleta Point-Coal Oil Point 1,960 10.2 0.1 99.9 4 60 40 0.152 3,03Coal Oil Point-Naples 7,280 10.2 0.1 99.9 1 60 40 0.152 11,27Naples-Point Orford 23,640 10.2 0.1 99.9 1 60 40 0.152 36,61Point Orford-Jalama 28,331 6.5 0.1 99.9 0.1 60 40 0.076 13,98Jalama-Spring Canyon 31,596 7.6 0.1 99.9 2 60 40 0.076 18,23Total 
Farnsworth and Warrick—Sources, Dispersal, and Fate of Fine Sediment Supplied to Coastal California—Scientific Investigations Report 2007–5254