Sediment Transport Modeling off the Northeast Coast of Florida

Gary A. Zarillo Florida Institute of Technology and Scientific Environmental Applications, Inc., Melbourne, FL

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Florida Inner Continental Shelf Study Areas

NE FL Shelf

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Geology of Shelf Sand Ridges

Origin and Dynamics

Numerical Modeling

• Strategy

• Applications

• Results

Combining Geological and Numerical Models to Assess the Impacts of Mining Sand Resources on the

Inner Continental Shelf of Northeast Florida

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Cretaceous Shannon Sandstone – Powder River Basin, WY

Cross-Bedded Shallow Water Sandstones

(Higley et al. 1997)

Geology of Shelf Sand Ridges

From Tillman 1985 4

Wave-Generated Bedforms at 12 m: A8 Shoal NE FL

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Sand Ridges in the Rock Record Mesozoic- Cenozoic Stratigraphy

From USGS 6

Oil Production from Ridge Sandstones

From USGS

Sussex B Sandstone

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Modern – Ancient Analogues

Cretaceous Period Sand Ridge A6 Sand Ridge NE Florida Continental Shelf

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Transgressive Sand Ridge Deposits – Fox Hills Sandstone

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Cross-bedded Storm Unit – Fox Hills Sandstone

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Modern Sand Ridge : A6 NE Florida Ancient Sand Ridge

See Tillman 1985; Rine et. al. 1991 for shelf sand ridge geology

Geology of Modern Shelf Sand Ridges

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Sand Ridge Origin in a Transgressive Barrier Island Setting

McBride and Moslow 1991 12

McBride and Moslow 1991

Shelf Sand Ridges – Florida Examples

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Indian River Shoal off East Central Florida Inner Continental Shelf

Beach Sand Borrow Area

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Sand Ridges/Linear Shoals of the NE FL Study Area

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Perspective Views of NE FL Shoals B11/B12

Shoals B12 and B11

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Model Grid Boundaries

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Spectral Wind-Wave Transformation Model CMS-WAVE Based on a spectral wave energy conservation equation: Considers wind input, shoaling, refraction, diffraction, and dissipation wave-current interaction

Circulation Model – CMS-FLOW Two-dimensional, finite-volume numerical solution of the depth-integrated continuity and momentum equations: Considers wave-current interaction, advection - diffusion, nonlinear continuity terms, forcing by water level, tidal constituents, flow-rate, wave stresses, and wind

Sand Transport Model – “LUND” Formulation Considers bed load, suspended load, wave-current interaction, initiation of motion, slope effects, and asymmetric wave velocity

The Numerical Models: USACOE/ERDC Coastal Modeling System

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Coastal Modeling System

http://cirp.usace.army.mil/products/index.html

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Model Setup

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- -

Tides

Wave Spectra

Water Level/ Winds

Model Setup – Boundary Time Series

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Storm-Related Wave Events

0

1

2

3

4

5

6

7

8

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12/11/97 3/21/98 6/29/98 10/7/98 1/15/99 4/25/99 8/3/99 11/11/99

Date

Hsi

g, m

0

2

4

6

8

10

12

14

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18

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Per

iod,

s

Significnt Wave Height, mPeak Period, s

Maximum Wave Event

Significant Wave Height, m

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Wave Model Calibration: NE Florida

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Measure v

Measured vs. Model Wave Period

Measured vs. Model Wave Direction

Wave Model

Calibration for

NE Florida

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• Time advancing runs of 2 years

• Event scale predictions for storm conditions

• Model predictions with/without borrow cuts

• Test single & multiple cuts from potential borrow areas

• Examine potential for modification of sediment transport

Numerical Modeling Strategy

ERDC/CHL Coastal Modeling System Coupled Wave and Circulation Models

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Model Test Location Borrow Cut Volume (m3) Duration Case1 B11_B12 Shoals None 0 2 years

Case 2 B11_B12 Shoals Single 600,000 2 years

Case 3 B11/B12 Shoals Multiple 8 million 2 years Case 4 A9 Shoal None 0 2 years

Case 5 A9 Shoal Single 1.2 million 2 years

Case 6 A9 Shoal Multiple 6 million 2 years

Case 7 A8 Shoal None 0 2 years

Case 8 A8 Shoal Single 1.2 million 2 years

Case 9 A8 Shoal Multiple 9.3 million 2 years

Case 10 A4-A6 Shoals None 0 2 years

Case 11 A4-A6 Shoals Single 2.8 million 2 years

Case 12 A4-A6 Shoals Multiple 18 million 2 years

Summary of NE Florida Model Test Cases

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B11-B12 Model Test Case 3

B11 B12

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Existing vs. Borrow Cuts: Hurricane Waves

Predicted Difference in Wave Height

B11

B12

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Event Scale Topographic Change

Deposition: Lower Shoreface

Erosion: Upper Shoreface

Deposition Lower Shoreface

Hurricane Floyd 1999 29

Model Predictions in the Littoral Environment

Numerical Recording Stations

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Predicted Annualized Net Littoral Sand Transport

Negative values indicate south-directed littoral sand transport 31

Predicted Difference Annualized Net Sand Transport in the Littoral Zone

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Shoal A6: Model Test Case 12

Federal Limit

Shoreline

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Predicted Event Scale Sand Transport

St. Augustine Inlet

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A6 Shoal Crest

Predicted Topographic Change – 24 Months at Shoal A6 (Predicted Topographic Change Over Ridge Crest +/-1 m)

No Sand Borrow Excavations

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Predicted Morphologic Change over Borrow Excavations (24-month model run A6 Shoal NE Florida Shelf)

Borrow Excavation

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Predicted Annualized Net Littoral Sand Transport A4 – A6 Shoals

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Predicted Difference: A4 – A6 Shoals Annualized Net Sand Transport in the Littoral Zone

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• Sand Ridges of NE Florida Continental Shelf are consistent with the sand geological model having clean sand units at the crest reworked and maintained by storms • Influence of the borrow cuts is at the event scale due to passing storms and associated long period waves • Along the NE Florida shoreline the influence of large borrow cuts is detectable but small compared to the annual sand budget and natural variability

Major Conclusions from the Model Simulations

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Acknowledgments

BOEMRE

U.S. Geological Survey

Florida Geologic Survey

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Higley D.K., M.P. Pantea and R.M. Slatt. 1997. 3-D Reservoir Characterization of the House Creek Oil Field, Powder River Basin, Wyoming, V1.00. U.S. Geological Survey Digital Data Series DDS-33.

McBride, R.A. and T.F. Moslow. 1991. Origin, evolution, and distribution of

shoreface sand ridges, Atlantic inner shelf, U.S.A. Marine Geology 97:57–85.

Rine, J.M., R.W. Tillman, S.J. Culver, and D.J.P. Swift. 1991. Generation of

late Holocene sand ridges on the middle continental shelf of New Jersey, USA – Evidence of formation in a mid-shelf setting based on comparisons with a nearshore ridge. International Association of Sedimentologists, Special Publication No. 14, pp. 395–423.

Tillman, R.W. 1985. A spectrum of shelf sands and sandstones. In: Tillman,

R.W., D. Swift, and R. Walker, eds. Shelf Sand and Sandstone Reservoirs. SEPM Short Course 13:1–46.

References

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