Potential Application of. Shore-Stabilizing Structures along an Open-Coast Shoreline. Christopher G. Creed, P.E. 23 rd Annual National Conference on

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1 23 rd Annual National Conference on Potential Application of Beach Preservation Technology February 3-5, 2010 Indialantic, FL Shore-Stabilizing Structures along an Open-Coast Shoreline Christopher G. Creed, P.E.

inlets, headlands, or other coastal features that

2 Open-Coast Shoreline An open-coast shoreline is one that is generally long, straight and not affected by inlets, headlands, or other coastal features that would significantly alter the alongshore transport of sand.

3 Deerfield Beach Hillsboro Beach Segment I Hillsboro Inlet Pompano Beach Segment II Fort Lauderdale Port Everglades Inlet Hollywood Segment III Hallandale Beach Open Coast Shorelines in Broward County

4 Palm Beach County Broward County Dominance from NE 6-7 times more southerly transport than northerly Unidirectional Transport Miami-Dade County NTS Offshore Wave Climatology

5 History of Shore Protection in Broward County Extensive groin use with limited nourishment ( s) Comprehensive beach nourishment (1970-present) Improvements e to sand bypassing at inlets Hillsboro Inlet Port Everglades Inlet (Pending) Consideration of strategic use of Shore-Stabilizing Structures to compliment continued beach nourishment

6 Southern Hollywood (1960 s) Miami Beach (1960 s) Historical Structure Use in Southeast FL

7 In 1967 there were approximately 230 groins along the Broward County shoreline

8 Hollywood Hallandale A1A R-125 R-126 Diplomat Hotel R-124 R-123 R-122 R-121 Hook Groin Diplomat Groins Photo date: Beach and Structure Conditions in Southern Hollywood and Hallandale Beach R-120

9 Present Conditions Localized persistent problematic shoreline conditions Desire to maintain consistent beach conditions along all of Broward County Reduced availability of sand resources Need to reduce demand on sand resources/ long-term beach management costs

10 Problematic Conditions Beach width < than 75-ft minimum desired Encroachment Locally high erosion rates Areas where alongshore sediment transport conditions contribute to erosion

11 SEGMENT III SEGMENT II SEGMENT I New River Inlet Dania Pier Balboa St Pompano Pier Fishing Pier (Anglin's) THE DIPLOMAT MIAMI-DADE CO. PALM BEACH CO. Deerfield Beach Hillsboro Beach HILLSBORO INLET Pompano Beach Lauderdale By The Sea GALT OCEAN MILE Fort Lauderdale PORT EVERGLADES John U. Lloyd Beach State Park Dania Beach Hollywood Hallandale R-1 R-3 R-5 R-7 R-9 R-11 R-13 R-15 R-17 R-19 R-21 R-23 R-25 R-27 R-29 R-31 R-33 R-35 R-37 R-39 R-41 R-43 R-45 R-47 R-49 R-51 R-53 R-55 R-57 R-59 R-61 R-63 R-65 R-67 R-69 R-71 R-73 R-75 R-77 R-79 R-81 R-83 R-86 R-88 R-90 R-92 R-94 R-96 R-98 R-100 R-102 R-104 R-106 R-108 R-110 R-112 R-114 R-116 R-118 R-120 R-122 R-124 R-126 R-128 D-3 D-5 0 Encroachment Narrow Beach Conditions MHWL Recession Beach Volume Loss Erosional Transport Gradient 0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50,000 55,000 60,000 65,000 70,000 75,000 80,000 85,000 90,000 95, , , , , , , ,000 Alonghsore Distance South of Palm Beach/Broward County Line (R-001) (feet) Problem Area Summary

Accelerating Transport Gradient Regional

12 Northern Fort Lauderdale (Galt Ocean Mile) Two Study Sites - Mild Erosion - Localized Encroachment - Narrow Beach Widths Southern Hollywood and Hallandale Beach - High Erosion - Regional Encroachment - Narrow Beach Widths - Accelerating Transport Gradient Regional 2d / Local 3d Delft3d Sediment Transport/ Morphological Model

13 Approaches Strategic Retreat Continue Renourishment Continue Renourishment with Co t ue e ou s e t t Shore-Stabilizing Structures

14 Structure Types Evaluated Impermeable T-Head Groins Semi-Permeable T-Head Groins Highly Permeable T-Head Groins Emergent Breakwaters Small, Emergent Breakwaters Semi-Submerged Breakwaters (MSL) Submerged Breakwaters (-3 ft, MSL) - Configured strictly for shore-stabilizing function - No consideration for aesthetics, environmental effects, etc.

15 Regional Nourishment Local Nourishment Requires high-frequency maintenance or stabilization Central Fort Lauderdale (Galt Ocean Mile)

16 1-Year Net Change Emergent Breakwaters (Not Designed for Tombolo Formation)

17 1-Year Net Change Fully Submerged Breakwaters (Designed to have minimal effect)

18 32 nd Street Breakwaters (Miami-Dade County) Predicted Downdrift Embayment Actual Downdrift Embayment 1-Year Emergent Breakwaters (Not Designed for Tombolo Formation)

19 Updrift Impoundment Problem Area Three Emergent Nearshore Breakwaters (Constructed in July 2002) Downdrift Erosion and Landward Offset Jan 1999 Jan 2003 Mar 2004 Updrift Impoundment Downdrift Erosion Embayment and Landward Offset Dec 2005 May 2007 Nov nd Street Breakwaters (Miami-Dade County)

20 1-Year 2-Year 3-Year Highly Permeable Groins with Fill (3-yr Results)

21 3-Year Net Change Highly Permeable Groins with Fill (3-yr Results)

22 Miami- Dade Broward County Encroachment/Highest Erosion Erosional Shoreline Southern Hollywood/Hallandale Beach

23 1-Year Net Change Permeable Groins (1-yr Results)

24 1-Year Net Change Emergent Breakwaters (1-yr Results)

25 1-Year Net Change Submerged Breakwaters (1-yr Results)

26 Unclear if shoreline condition is related to structures Two low-crested, submerged breakwaters Unclear if recession is downdrift effect of structures Jan 29, 2003 Mar 4, 2004 No apparent influence of structures to shoreline Salient -- Not definitive that it is related only to structures. t Similar features are observed along other areas of the coastline at this same time. May 8, 2007 Mar 5, 2009 Northern Sunny Isles Submerged Breakwaters (Miami-Dade County)

27 109 R-110 R-115 Golden Beach Hallandale Hollywood R-120 R-125 Hollywood/Hallandale Study Area Sunny-Isles Submerged Breakwaters Accretion Erosion Accretion Stable Erosion Accretion -80,000-70,000 Southerly -60,000-50,000-40,000-30,000-20,000-10,000 Sediment Transport Rate (cy/yr) 0 Northerly 10,000 20, , , , , , , , , , , , ,000 Southern Broward County Predicted Transport Conditions

28 1-Year 2-Year 3-Year Small, Emergent Breakwaters (3-yr Results) (Designed for Very Weak Salients)

29 3-Year Net Change Small, Emergent Breakwaters (3-yr Results) (Designed for Very Weak Salients Mild Effect)

30 1-Year 2-Year 3-Year Predicted Multiple Year Downdrift Volume Change for Various Alternatives

31 Miami- Dade Broward County Downdrift Beach Structure Application -27,800 cy/yr Existing -6,200 cy/yr -14,700 cy/yr Conditions Structure Induced -59,000 cy/yr 0 cy/yr (stable to accretional) Ttl Total -65,200 cy/yr 0 cy/yr 1-yr Post Structure Induced Total -17,700 cy/yr 0 cy/yr (stable to accretional) -23,900 cy/yr 0 cy/yr 3-yr Post Effect to Sand Budget (Example for Small, Emergent Breakwaters Mild Effect)

32 Miami- Dade Broward County Downdrift Beach Structure Application Maintain Beach Conditions with Nourishment ~ $1.25 million per year Structures and Nourish Downdrift Beach at 1-Yr Post Erosion Rate ~ $2.33 million per year Structures and Nourish Downdrift Beach at 3-Yr Post Erosion Rate ~ $0.77 million per year Effect to Beach Management Economics (Example for Small, Emergent Breakwaters Mild Effect)

33 Effect to Shoreline Structures and Nourish Downdrift Beach at 3-Yr Post Erosion Rate Requires permanent landward relocation of downdrift beach (R-125 to R-128) -> 45 and 65 feet Existing beach width is only 75 to 110 feet Effect is predicted to extend at least 3,000 ft south of structure field

34 Conclusions Calibrated 2D/3D Delft3D model appears to simulate expected beach response to shorestabilizing structures (groins and breakwaters) reasonably well Predicted results for the structure alternatives tested are generally consistent with observations at other structure projects in southeast Florida

35 Conclusions Predictions suggest that the use of groins or breakwaters will improve beach width and stability along the stabilized and updrift shoreline, but will also induce erosion along the adjacent downdrift shoreline Modeling demonstrated that the overall extent of predicted structure-induced erosion varied little among tested alternatives

36 Conclusions Northern Fort Lauderdale Structures are not recommend where existing erosion rates are relatively l mild Predicted structure-induced beach change is not expected to result in a net improvement of regional beach conditions o

37 Conclusions Hollywood/Hallandale Beach If shoreline planform change (i.e., downdrift retreat) is acceptable, shore-stabilizing structures may potentially reduce the long-term demand on sand resources and the cost of beach management at that location With such changes, however, it may not be possible to maintain desired minimum beach widths downdrift of structures due to location of development line

38 Thank You 23 rd Annual National Conference on Potential Application of Beach Preservation Technology February 3-5, 2010 Indialantic, FL Shore-Stabilizing Structures along an Open-Coast Shoreline Christopher G. Creed, P.E.

PORT EVERGLADES SAND BYPASS PROJECT

28 th Annual National Conference on Beach Preservation Technology February 4, 2015 Clearwater Beach, FL PORT EVERGLADES SAND BYPASS PROJECT AN IMPORTANT FUTURE SAND SOURCE FOR SOUTHEAST FLORIDA BEACHES