Josh Bearman, Carl Friedrichs, Bruce Jaffe, Amy Foxgrover Spatial and Temporal Trends in Tidal Flat Shape in San Francisco Bay Josh Bearman, Carl Friedrichs, Bruce Jaffe, Amy Foxgrover Main Points 1) On tidal flats, sediment (especially mud) moves away from high concentration areas and towards areas of weaker energy. 2) Tides and/or abundant sediment supply favor a convex upward profile; waves and/or sediment loss favor a concave upward profile. 3) South San Francisco Bay provides a case study supporting these trends, both in space and in time. Aerial Photo of flats near Dumbarton Bridge, South San Francisco Bay Courtesy http://asapdata.arc.nasa.gov

Spatial and Temporal Trends in Tidal Flat Shape in San Francisco Bay Josh Bearman, Carl Friedrichs, Bruce Jaffe, Amy Foxgrover Visit Josh at TheHotSeats.net Main Points 1) On tidal flats, sediment (especially mud) moves away from high concentration areas and towards areas of weaker energy. 2) Tides and/or abundant sediment supply favor a convex upward profile; waves and/or sediment loss favor a concave upward profile. 3) South San Francisco Bay provides a case study supporting these trends, both in space and in time. Aerial Photo of flats near Dumbarton Bridge, South San Francisco Bay Courtesy http://asapdata.arc.nasa.gov

South Bay Salt Pond Project First ponds leveed in 1854 Currently 26,000 acres of salt ponds in South Bay October, 2000 61% of ponds sold to large conglomerate of GOs, NGOs, private foundations.

What moves sediment across flats? Ans: Tides plus concentration gradients; (i) Due to energy gradients: Tidal advection High energy waves and/or tides Low energy waves and/or tides Higher sediment concentration Tidal advection High energy waves and/or tides Low energy waves and/or tides Lower sediment concentration 1

What moves sediment across flats? Ans: Tides plus concentration gradients; (ii) Due to sediment supply: Tidal advection Sediment source from river or local runoff Low energy waves and/or tides Higher sediment concentration “High concentration boundary condition” Net settling of sediment Tidal advection Lower sediment concentration “High concentration boundary condition” Net settling of sediment 2

Landward Tide-Induced Sediment Transport Maximum tide and wave orbital velocity distribution across a linearly sloping flat: z = R/2 h(t) = (R/2) sin wt x = L Z(x) h(x,t) z = 0 z = - R/2 x = 0 x x = xf(t) Spatial variation in tidal current magnitude Spatial variation in wave orbital velocity 0 0.2 0.4 0.6 0.8 1 3.0 2.5 2.0 1.5 1.0 0.5 0 0.2 0.4 0.6 0.8 1 1.4 1.2 1.0 0.8 0.6 0.4 0.2 UT90/UT90(L/2) UW90/UW90(L/2) Seaward Wave-Induced Sediment Transport Landward Tide-Induced Sediment Transport x/L x/L 3

Josh Bearman, Carl Friedrichs, Bruce Jaffe, Amy Foxgrover Spatial and Temporal Trends in Tidal Flat Shape in San Francisco Bay Josh Bearman, Carl Friedrichs, Bruce Jaffe, Amy Foxgrover Main Points 1) On tidal flats, sediment (especially mud) moves away from high concentration areas and towards areas of weaker energy. 2) Tides and/or abundant sediment supply favor a convex upward profile; waves and/or sediment loss favor a concave upward profile. 3) South San Francisco Bay provides a case study supporting these trends, both in space and in time. Aerial Photo of flats near Dumbarton Bridge, South San Francisco Bay Courtesy http://asapdata.arc.nasa.gov

Josh Bearman, Carl Friedrichs, Bruce Jaffe, Amy Foxgrover Spatial and Temporal Trends in Tidal Flat Shape in San Francisco Bay Josh Bearman, Carl Friedrichs, Bruce Jaffe, Amy Foxgrover Main Points 1) On tidal flats, sediment (especially mud) moves away from high concentration areas and towards areas of weaker energy. 2) Tides and/or abundant sediment supply favor a convex upward profile; waves and/or sediment loss favor a concave upward profile. 3) South San Francisco Bay provides a case study supporting these trends, both in space and in time. Aerial Photo of flats near Dumbarton Bridge, South San Francisco Bay Courtesy http://asapdata.arc.nasa.gov

South San Francisco Bay Tidal Flats: San Mateo Bridge Dumbarton Bridge South San Francisco Bay MHW to MLLW MLLW to - 0.5 m 700 tidal flat profiles in 12 regions, separated by headlands and creek mouths. 4 km 12 1 11 2 3 10 4 9 5 8 7 Semi-diurnal tidal range up to 2.5 m 6 6

7 Dominant mode of profile shape variability determined through eigenfunction analysis: Across-shore structure of first eigenfunction San Mateo Bridge Dumbarton Bridge South San Francisco Bay MHW to MLLW MLLW to - 0.5 m First eigenfunction (deviation from mean profile) 90% of variability explained Mean + positive eigenfunction score = convex-up Mean + negative eigenfunction score = concave-up Amplitude (meters) Normalized seaward distance across flat Mean concave-up profile (scores < 0) Height above MLLW (m) Mean profile shapes Normalized seaward distance across flat Mean tidal flat profile Mean convex-up profile (scores > 0) 12 Profile regions 1 11 2 3 10 4 9 8 5 4 km 7 6 7

Significant spatial variation is seen in convex (+) vs Significant spatial variation is seen in convex (+) vs. concave (-) eigenfunction scores: 8 4 -4 10-point running average of profile first eigenfunction score Convex Concave 12 Profile regions 1 11 2 3 10 Eigenfunction score 7 4 9 Regionally-averaged score of first eigenfunction 8 4 2 -2 5 Convex Concave 8 4 km 10 7 6 9 6 5 2 11 12 1 4 3 Tidal flat profiles 8

Average fetch length (km) Net 22-year deposition (m) -- Tide range & deposition are positively correlated to eigenvalue score (favoring convexity). 1 2 3 4 5 6 7 8 9 10 11 12 Profile regions 4 km -- Fetch & grain size are negatively correlated to eigenvalue score (favoring concavity). Profile region 1 3 5 7 9 11 4 2 -2 3 1 Average fetch length (km) Convex Concave Eigenfunction score r = - .82 Fetch Length Profile region 1 3 5 7 9 11 4 2 -2 2.5 2.4 2.3 2.2 2.1 Mean tidal range (m) Convex Concave Eigenfunction score Tide Range r = + .87 1 .8 .6 .4 .2 -.2 -.4 1 3 5 7 9 11 4 2 -2 Profile region Net 22-year deposition (m) Convex Concave Eigenfunction score Deposition r = + .92 1 3 5 7 9 11 4 2 -2 40 30 20 10 Profile region Mean grain size (mm) Convex Concave Eigenfunction score r = - .61 Grain Size 9

Tide + Deposition – Fetch Explains 89% of Variance in Convexity/Concavity San Mateo Bridge Dumbarton Bridge South San Francisco Bay MHW to MLLW MLLW to - 0.5 m 4 2 -2 Observed Score Modeled Score Convex Concave r = + .94 r2 = .89 Eigenfunction score Modeled Score = C1 + C2 x (Deposition) + C3 x (Tide Range) – C4 x (Fetch) 1 3 5 7 9 11 Profile region Increased tide range Convex-upwards 1 2 3 4 5 6 7 8 9 10 11 12 Profile regions Increased deposition Flat elevation Increased fetch Concave-upwards Increased grain size Seaward distance across flat 10

Josh Bearman, Carl Friedrichs, Bruce Jaffe, Amy Foxgrover Spatial and Temporal Trends in Tidal Flat Shape in San Francisco Bay Josh Bearman, Carl Friedrichs, Bruce Jaffe, Amy Foxgrover Main Points 1) On tidal flats, sediment (especially mud) moves away from high concentration areas and towards areas of weaker energy. 2) Tides and/or abundant sediment supply favor a convex upward profile; waves and/or sediment loss favor a concave upward profile. 3) South San Francisco Bay provides a case study supporting these trends, both in space and in time. Aerial Photo of flats near Dumbarton Bridge, South San Francisco Bay Courtesy http://asapdata.arc.nasa.gov

(Jaffe et al. 2006) 11

10-point running average of profile first eigenfunction score 2 3 4 5 6 7 8 9 10 11 12 Regions 4 km Regionally-averaged score of first eigenfunction Eigenfunction score 12

10-point running average of profile first eigenfunction score 2 3 4 5 6 7 8 9 10 11 12 Regions 4 km Regionally-averaged score of first eigenfunction Eigenfunction score Inner regions (5-11) tend to be more convex 12

South San Francisco Bay Variation of External Forcings in Time: Sed load at delta (Ganju et al. 2008) San Mateo Bridge Dumbarton Bridge South San Francisco Bay MHW to MLLW MLLW to - 0.5 m San Jose 13

- Trend of Scores in Time (+ = more convex, - = more concave) 1 2 3 4 5 6 7 8 9 10 11 12 Regions 4 km Region 1 Region 2 Region 3 -1 1 -2 -1 -2 4 2 1 Score Region 4 Region 5 Region 6 Score Region 7 Region 8 Region 9 4 2 -1 2 1 -1 Score Region 10 Region 11 Region 12 Score 1900 1950 2000 1900 1950 2000 1900 1950 2000 14 Year Year Year

- Trend of Scores in Time (+ = more convex, - = more concave) - Outer regions are getting more concave in time (i.e., eroding) - Inner regions are not (i.e., more stable) 1 2 3 4 5 6 7 8 9 10 11 12 Regions 4 km Region 1 Region 2 Region 3 -1 1 -2 -1 -2 4 2 1 Score Region 4 Region 5 Region 6 Outer regions Score Inner regions Region 7 Region 8 Region 9 4 2 -1 2 1 -1 Score Region 10 Region 11 Region 12 Outer regions Score 1900 1950 2000 1900 1950 2000 1900 1950 2000 14 Year Year Year

- Trend of Scores in Time (+ = more convex, - = more concave) CENTRAL VALLEY SEDIMENT DISCHARGE Outer regions become more concave as sediment discharge decreases 1 2 3 4 5 6 7 8 9 10 11 12 Regions 4 km Region 1 Region 2 Region 3 -1 1 * * -2 * -1 -2 4 2 1 6 4 2 6 4 2 Sediment Disch. (MT) 6 4 2 Score Region 4 Region 5 Region 6 Outer regions * * 6 4 2 6 4 2 6 4 2 Sediment Disch. (MT) Score Inner regions *SIGNIFICANT Region 7 Region 8 Region 9 4 2 -1 2 1 -1 * 6 4 2 6 4 2 6 4 2 Sediment Disch. (MT) Score Region 10 Region 11 Region 12 Outer regions * 6 4 2 6 4 2 6 4 2 Sediment Disch. (MT) Score 1900 1950 2000 1900 1950 2000 1900 1950 2000 15 Year Year Year

- Trend of Scores in Time (+ = more convex, - = more concave) PACIFIC DECADAL OSCILLATION No significant relationship to changes in shape 1 2 3 4 5 6 7 8 9 10 11 12 Regions 4 km Region 1 Region 2 Region 3 1 -1 -1 1 1 -1 -2 1 -1 -1 -2 4 2 1 Score PDO Index Region 4 Region 5 Region 6 Outer regions 1 -1 1 -1 1 -1 Score PDO Index Inner regions Region 7 Region 8 Region 9 1 -1 4 2 -1 1 -1 2 1 -1 1 -1 Score PDO Index Region 10 Region 11 Region 12 Outer regions 1 -1 1 -1 1 -1 Score PDO Index 1900 1950 2000 1900 1950 2000 1900 1950 2000 16 Year Year Year

- Trend of Scores in Time (+ = more convex, - = more concave) Relationship to preceding deposition or erosion Inner and outer regions more concave after erosion, more convex after deposition 1 2 3 4 5 6 7 8 9 10 11 12 Regions 4 km Region 1 Region 2 Region 3 -1 1 -2 .3 -.3 -.4 -.2 -.4 -1 -2 4 2 1 change (m) Bed Score Region 4 Region 5 Region 6 Outer regions * .2 -.2 .4 * .3 -.3 change (m) Bed Score Inner regions *SIGNIFICANT Region 7 Region 8 Region 9 4 2 -1 * .6 .3 * 2 1 -1 1 .5 .6 .3 Score change (m) Bed Region 10 Region 11 Region 12 Outer regions * .6 .3 * .2 -.2 -.3 change (m) Bed Score 1900 1950 2000 1900 1950 2000 1900 1950 2000 17 Year Year Year

- Trend of Scores in Time (+ = more convex, - = more concave) SAN JOSE RAINFALL Inner regions more convex when San Jose rainfall increases 1 2 3 4 5 6 7 8 9 10 11 12 Regions 4 km Region 1 Region 2 Region 3 20 15 10 -1 1 20 15 10 -2 20 15 10 -1 -2 4 2 1 Rainfall (in) San Jose San Jose Score Region 4 Region 5 Region 6 Outer regions 20 15 10 20 15 10 20 15 10 * Rainfall (in) San Jose Score Inner regions *SIGNIFICANT Region 7 Region 8 Region 9 20 15 10 4 2 -1 20 15 10 2 1 -1 20 15 10 * * Score Rainfall (in) San Jose Region 10 Region 11 Region 12 Outer regions 20 15 10 20 15 10 20 15 10 Rainfall (in) San Jose Score 1900 1950 2000 1900 1950 2000 1900 1950 2000 18 Year Year Year

- Trend of Scores in Time (+ = more convex, - = more concave) CHANGES IN TIDAL RANGE THROUGH TIME No significant relationships to temporal changes in tidal range 1 2 3 4 5 6 7 8 9 10 11 12 Regions 4 km Region 1 Region 2 Region 3 1.8 1.7 -1 1 1.8 1.7 -2 1.8 1.7 -1 -2 4 2 1 Range (m) Tidal Score Region 4 Region 5 Region 6 Outer regions 1.8 1.7 1.8 1.7 1.8 1.7 Range (m) Tidal Score Inner regions Region 7 Region 8 Region 9 1.8 1.7 4 2 -1 1.8 1.7 2 1 -1 1.8 1.7 Score Range (m) Tidal Region 10 Region 11 Region 12 Outer regions 1.8 1.7 1.8 1.7 1.8 1.7 Range (m) Tidal Score 1900 1950 2000 1900 1950 2000 1900 1950 2000 19 Year Year Year

Significance (slope/std err) Temporal Analysis: Multiple Regression Less Central Valley sediment discharge: Outer regions more concave. More San Jose Rains: Inner regions more convex. Recent deposition (or erosion): Middle regions more convex (or concave) Significance (slope/std err) Region Mult Reg Rsq CV Seds SJ Rainfall Dep/Eros r1 0.82 4.21 ––– r2 0.73 3.19 r3 0.71 3.07 r4 0.55 2.10 r5 0.95 8.18 3.43 r6 0.53 1.51 r7 0.35 1.39 r8 0.47 1.29 1.12 r9 0.66 2.03 2.4 r10 0.94 3.41 7.77 r11 0.46 1.05 1.37 r12 0.51 12 1 2 11 3 San Jose 10 4 9 5 8 7 6 20

Josh Bearman, Carl Friedrichs, Bruce Jaffe, Amy Foxgrover Spatial and Temporal Trends in Tidal Flat Shape in San Francisco Bay Josh Bearman, Carl Friedrichs, Bruce Jaffe, Amy Foxgrover Main Points 1) On tidal flats, sediment (especially mud) moves away from high concentration areas and towards areas of weaker energy. 2) Tides and/or abundant sediment supply favor a convex upward profile; waves and/or sediment loss favor a concave upward profile. 3) South San Francisco Bay provides a case study supporting these trends, both in space and in time. Aerial Photo of flats near Dumbarton Bridge, South San Francisco Bay Courtesy http://asapdata.arc.nasa.gov