A Sediment Budget for Two Reaches of Alameda Creek

(1900s through 2006)

Paul Bigelow, Sarah Pearce, Lester McKee, and Alicia Gilbreath

Study Questions• Are the study reaches supplying a major source

of sediment to the flood control channel?

• What are the dominant processes, and what are the rates of erosion and amount of storage?

• What proportion of total sediment load at Niles is derived from the study reaches?

• How has the channel changed through time?

Alameda Creek

Watershed

Area BehindDams

Drainage Area Drainage Area % Area

Gage Location Below Dams (km2) total (km2) Above DamsArroyo de La Laguna at Verona Gage 670 1044 36%Alameda Creek near Welch Ck Gage 35 376 91%Alameda Creek at Niles Gage 821 1639 50%

Study Area

Brief Watershed History• Pre-1900: channel ditching, groundwater wells, small dams• 1900: Ditching and draining of Tulare Lake• 1911: ADLL incision rate of 6 in/yr

1925: Calaveras Dam, gravel mining1950s: Four largest flood events on record1964: San Antonio Dam1968: Del Valle Dam1970s: Flood Control Channel construction1980s to 2000s: Flood Control Channel dredging

Oblique view of Pleasanton and Dublin (looking west) during the 1955 flood

Historical Flow Changes

Lower Subreach

Upper Subreach

Arroyo De La Laguna

Arroyo De La Laguna

Arroyo De La Laguna

Alameda Creek

Sediment Budget Methods

• Incision – bed elevation surveys 1959, 1971, 2007

• Bank Erosion & Bar Storage – field surveys and air photo analysis

• Cross Section Surveys – historical and current

• Flood Plain Storage – field surveys

- Only subset of data collected for Alameda Creek Reach(little incision, 90% of drainage area above dams)

Compare Reaches w/ Watershed

• Balance the Budget

• Estimate Yield at Gages (rating curves)

• Estimate Yield for Ungaged tributaries (reservoir sedimentation rate)

• Compare Reaches w/ Niles Gage

+Verona Gage

+Welch Gage

+Study Reaches

+Ungaged Tribs

= Niles Gage?

Sediment Budget Periods

• 1901 – 1959

• 1959 – 1971

• 1971 – 1993

• 1993 – 2006

63

68

73

78

83

88

0 1000 2000 3000 4000 5000

Distance Moving Upstream (meters)

Ele

vati

on

(m

eter

s N

AV

D)

1959 Top of Bank (Alameda Co)

1959 Bed Elevation (Alameda Co)

Assumed 1901 Bed Elevation

Confluence

Paloma Br

Downstream RR Br

Verona Br

4.5 m ave total incision depth6 – 10 cm/yr

ResultsLong ProfilesArroyo De La Laguna

Bed Elevation~1901 – 1959

ConfluencePaloma Br

Downstream RR Br

Verona Br

60

65

70

75

80

85

0 1000 2000 3000 4000 5000 6000

Distance Moving Upstream (meters)

Ele

vati

on

(m

eter

s N

AV

D)

1959 Bed Elevation (Alameda Co)

1971 Bed Elevation (FEMA)

1-2 m incision depth7 – 15 cm/yr

1959 to 1971 Bed Elevation

Verona Bridge

Downstream RR Bridge

Paloma BridgeConfluence

60

65

70

75

80

85

0 1000 2000 3000 4000 5000 6000

Distance Moving Upstream (m)

Ele

vati

on

(m

NA

VD

)

1971 Bed Elevation (FEMA)

2007 Bed Elevation (SFEI)

1971 to 2007 Bed Elevation

0.5 – 0.8 m incision2 – 6 cm/yr

0.75 maggradation

Incision Pattern Over TimeIncision Migrating Upstream

Confluence

VeronaBridge

DownstreamRR Bridge

PalomaBridge

60

65

70

75

80

85

0 1000 2000 3000 4000 5000 6000

Distance Moving Upstream (m)

Ele

vati

on

(m

eter

s N

AV

D)

1959 Bed Elevation (Alameda Co)

1971 Bed Elevation (FEMA)

2007 Bed Elevation (SFEI)

knickpoint1959

knickpoint1971

2007?

Further Upstream

Paloma Br

DownstreamRR Br

Castlewood Br

Bernal Ave

Verona Br

60

65

70

75

80

85

90

95

100

0 2000 4000 6000 8000 10000 12000

Distance Moving Upstream (meters)

Ele

vati

on

(m

eter

s N

AV

D)

1959 Bed Elevation (Alameda Co)

1971 Bed Elevation (FEMA)

1998 Bed Elevation (West Yost)

knickpoint1998?

knickpoint1971

knickpoint1959

Bank Erosion & Bar StorageAerial Photograph Analysis

• Assessed entire study reach

• Focused on four locations

• Four time periods

• Quantified bank erosion and bar storage

1939 Photo

1950 Photo

1966 Photo

1993 Photo

2005 Photo

Area (m2)

0

1735

1390

5837

8962

Location C

2005 Photo

1939-1950

1950-1966

1966-1993

1993-2005Retreat rate 0.0 m/yr

Retreat rate 0.9 m/yr

Retreat rate 0.6 m/yr

Retreat rate 3.8 m/yr

Erosion Location

Time Period

A B C D

1939-1950 120 0 0 0

1950-1966 320 620 830 0

1966-1993 420 300 400 290

1993-2005 1,900 1,420 3,700 1,050

Bank erosion (metric tonnes/yr)

Channel Cross Sections

Channel Cross Sections

5-6 m5-6 m

Flood Plain Storage

Arroyo De La Laguna - Upper Reach - Cross Section 21

-12-11-10

-9-8-7-6-5-4-3-2

135 140 145 150 155 160 165 170 175 180 185 190 195 200 205 210 215

Distance (m)

Rel

ativ

eE

lev

atio

n(m

)

Sediment Budget by Process - ADLLArroyo De La Laguna - Sediment Budget by Process

-10000

-5000

0

5000

10000

15000

20000

1901 - 1958 1959 - 1971 1972 - 1993 1994 - 2006

Budget Period

Rat

e (t

on

nes

/yea

r)

Flood Plain StorageBar StorageBank ErosionBed Incision

Arroyo De La Laguna - Net Budget

-5000

0

5000

10000

15000

20000

1901 - 1958 1959 - 1971 1972 - 1993 1994 - 2006

Budget Period

Rat

e (t

on

nes

/yea

r)

Alameda Creek ReachAlameda Creek - Sediment Budget by Process (incomplete)

-10000

-5000

0

5000

10000

15000

20000

1901 - 1958 1959 - 1971 1972 -1993 1994 - 2006

Budget Period

Rat

e (t

on

nes

/yea

r)

Landslide

Bar Storage

Bank Erosion

Bed Incision

No Data

Alameda Creek - Net Sediment Budget (incomplete)

0

5000

10000

15000

20000

1901 - 1958 1959 - 1971 1972 -1993 1994 - 2006

Budget Period

Ra

te (

ton

ne

s/y

ea

r)

No Data

Overall Watershed Comparisonfor Recent Period (1994 – 2006)

  Sediment Yield

Area tonnes/year % of Total

ADLL at Verona Gage 104,000 63

Alameda Creek near Welch Ck Gage 3,400 2

Arroyo de La Laguna Study Reach 8,400 5

Alameda Creek Study Reach 320 0.2

Ungaged areas 47,908 29

All Areas above Niles Gage 164,000

Alameda Creek at Niles Gage 156,000

Within5%

Study Reaches Comparison to Niles Gage

Time PeriodNiles Gage

(tonnes/yr)

Study Reaches

Combined (tonnes/yr) % of Niles

1959-1971 74,000 19,300 26

1972-1993 90,000 320 0.4

1994-2006 156,000 8,700 6

Study Area Sediment Yield Comparison to Regional Values

ADLL at Verona Gage

155 tn km-2 yr-1Alameda CreekWelch Ck Gage

97 tn km-2 yr-1

Ungaged areas

413 tn km-2 yr-1

All Areas aboveNiles Gage

200 tn km-2 yr-1

10

100

1000

10000

10 100 1000 10000Drainage Area (km2)

Sed

imen

t Y

ield

(to

nn

es k

m-2 y

r-1)

Alameda County

Contra Costa County

Marin County

Monterey County

Sonoma County

Santa Clara County

Study Area

Sediment Budget Take Home Points

• Sediment budget has adjusted over several periods of land use alteration and disturbance from floods

• Budget dominated by incision in earlier periods, now adjusting through bank erosion

• ADLL sediment yield is high for a short reach (0.25% of total stream network length)

• But ADLL comprises a small portion of watershed sediment yield (6% of total yield)

Future Channel Evolution

• Channel Evolution Models

• Process-based classification

• Describe channel form as it responds to a disturbance

• Shows typical channel adjustments to return a balance of sediment transport capacity

Future Response of ADLL

Conceptual Scenarios:

A(incision)

B(aggradation)

C(most probable)

Peak Discharge

Sediment Load

Predicted Sediment Supply Response from reach

~ 50% ~ 200% ~ 10%

Next Steps - Recommendations

• Monitor future channel adjustment in ADLL, and continue to stabilize the reach

• Given management changes on Alameda Creek, monitor future channel response for sediment supply increase

• Conduct a phased watershed sediment budget– Phase 1: Quantitatively (on public lands) and qualitatively (on

private lands) assess feasibly manageable sediment– Phase 2 (if needed): Quantitative evaluation of manageable

sediment on private lands

• Conduct numerical modeling to understand sediment routing to and deposition within the Flood Control Channel