Sediment Transport Modeling off the Northeast Coast of Florida

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

1 Florida Inner Continental Shelf Study Areas

NE FL Shelf

2 Combining Geological and Numerical Models to Assess the Impacts of Mining Sand Resources on the Inner Continental Shelf of Northeast Florida

Geology of Shelf Sand Ridges Origin and Dynamics

Numerical Modeling • Strategy • Applications • Results

3 Geology of Shelf Sand Ridges

Cretaceous Shannon Sandstone – Powder River Basin, WY

(Higley et al. 1997)

Cross-Bedded Shallow Water Sandstones

From Tillman 1985 4

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

5 Sand Ridges in the Rock Record Mesozoic- Cenozoic Stratigraphy

From USGS 6 Oil Production from Ridge Sandstones

Sussex B Sandstone

7 From USGS Modern – Ancient Analogues

A6 Sand Ridge Cretaceous Period Sand Ridge NE Florida Continental Shelf

8 Transgressive Sand Ridge Deposits – Fox Hills Sandstone

9 Cross-bedded Storm Unit – Fox Hills Sandstone

10 Geology of Modern Shelf Sand Ridges

Ancient Sand Ridge Modern Sand Ridge : A6 NE Florida

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

11 Sand Ridge Origin in a Transgressive Barrier Island Setting

McBride and Moslow 1991 12 Shelf Sand Ridges – Florida Examples

McBride and Moslow 1991 13 Indian River Shoal off East Central Florida Inner Continental Shelf Beach Sand Borrow Area

14 Sand Ridges/Linear Shoals of the NE FL Study Area

15 Perspective Views of NE FL Shoals B11/B12

Shoals B12 and B11

16 Model Grid Boundaries

17 The Numerical Models: USACOE/ERDC Coastal Modeling System

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

18 Coastal Modeling System

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

19 Model Setup

- -

20 Model Setup – Boundary Time Series Water Level/ Winds

Tides

Wave Spectra

21 Storm-Related Wave Events

9 20

SignificntSignificant Wave Wave Height,Height, m m 8 18 Peak Period, s 16 7

Maximum Wave Event 14 6 12 5 10 Period, s Hsig, m Hsig, 4 8 3 6

2 4

1 2

0 0 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

22 Wave Model Calibration: NE Florida

23 Wave Model Measure v Calibration for NE Florida

Measured vs. Model Wave Period

Measured vs. Model Wave Direction

24 Numerical Modeling Strategy

ERDC/CHL Coastal Modeling System Coupled Wave and Circulation Models

• 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

25 Summary of NE Florida Model Test Cases

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

26 B11-B12 Model Test Case 3

B11 B12

27 Predicted Difference in Wave Height

Existing vs. Borrow Cuts: Hurricane Waves

B11

B12

28 Event Scale Topographic Change

Deposition Lower Shoreface Deposition: Lower Shoreface Erosion: Upper Shoreface

Hurricane Floyd 1999 29 Model Predictions in the Littoral Environment

Numerical Recording Stations

30 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

32 Shoal A6: Model Test Case 12

Federal Limit

Shoreline

33 Predicted Event Scale Sand Transport

St. Augustine Inlet

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

A6 Shoal Crest

No Sand Borrow Excavations

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

Borrow Excavation

36 Predicted Annualized Net Littoral Sand Transport A4 – A6 Shoals

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

38 Major Conclusions from the Model Simulations

• 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

39 Acknowledgments BOEMRE U.S. Geological Survey Florida Geologic Survey

40 References

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.

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