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. 41 .