2014 FSBPA Annual Conference Effectiveness of Beach Nourishment in Response to Sea Level Rise Navarre Beach Santa Rosa County July 18, 2005 Lovers Key Lee County April 23, 2012 South County St. Lucie County November 30, 2012 Michael Walther, P. E., D. CE Andrew Condon, Ph. D. September 24, 2014
Presentation Outline Beach Management Objectives Sea Level Rise in Florida - historical & projected Effectiveness of Alternatives relative to Objectives Beach Fill Managed Retreat Coastal Armoring Seawalls Conclusions 2
Classic Beach Management Objectives Protection - of upland property & infrastructure (storm-damage reduction) Preserve Land Enhance Recreational Beach Habitat Restoration (via creation, restoration, &/or expansion) (turtle nesting, shorebirds, &/or beach mice) 3 Reference: USACE National Economic Development Manuals Chapter 161 - Florida Statutes
MSL Trend Location Period (mm/yr) (in/yr) Fernandina Beach 1897-2006 2.02 0.08 Mayport 1928-2006 2.40 0.09 Daytona Beach Shores 1925-1983 2.32 0.09 Miami Beach 1931-1981 2.39 0.09 Vaca Key 1971-2006 2.78 0.11 Key West 1913-2006 2.24 0.09 Naples 1965-2006 2.02 0.08 Fort Meyers 1965-2006 2.40 0.09 St. Petersburg 1947-2006 2.36 0.09 Clearwater Beach 1973-2006 2.43 0.10 Cedar Key 1914-2006 1.80 0.07 Apalachicola 1967-2006 1.38 0.05 Panama City 1973-2006 0.75 0.03 Pensacola 1923-2006 2.10 0.08 Average: 2.10 0.08 Florida Historical Sea Level Rise Adapted From: "Sea Level Variations of the United States 1854-2006", NOAA December 2009 4
Florida Projected Sea Level Change - 2065 0.34 2.82 0.24 2.72 0.30 2.78 0.44 2.91 0.38 2.86 0.38 2.86 0.39 2.87 State-wide Lowest to Highest Range per USACE Overall: 0.24 feet to 2.91 feet 0.39 2.87 0.33 2.80 0.40 2.87 0.37 2.84 5 Adapted from: USACE Sea-Level Change Curve Calculator https://corpsclimate.us/ccaceslcurves.cfm
Sea Level Rise (ft above 2014 MSL) 7 6 Florida Projected Sea Level Change Florida: All Gauges Average 2065 5 4 3 2 1 0 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100 NOAA Low / USACE Low NOAA Int Low / USACE Int NOAA Int High USACE High NOAA High 6 Adapted from: USACE Sea-Level Change Curve Calculator https://corpsclimate.us/ccaceslcurves.cfm
Alternatives Beach Fill Managed Retreat No Action to abate erosion Coastal Armoring Seawalls 7
Sea Level Rise Effect on Beach Fills future nourishment to offset longshore sediment transport gradient & sea level rise V t = h + B R 0 t + W S t S 0 t Where V t R 0 t S t S 0 t = Volumetric rate of nourishment addition per unit length of beach (cyds. / ft. / yr.) = Existing background erosion rate (ft. / yr.) = Rate of sea level rise (ft. / yr.) = Existing sea level rise rate (ft. / yr.) W = Width of the active beach profile (ft.) h = Depth of closure (ft.) B = Berm height (ft.) Volume required for present rate of SLR Amount due to the increased SLR rate 8 Adapted from: Dean, R.G and Dalrymple, R.A., 2002. Coastal Processes with Engineering Applications. Cambridge: Cambridge University Press, 475 p.
Managed Retreat No Action Allows the shoreline to migrate landward unimpeded. Buildings & infrastructure either demolished or relocated. 9 From: Beaver, J.W., Climate Readiness Planning at the SWFRPC and CHNEP 2009 to 2013. October 17, 2013.
Sea Level Rise Shoreline Recession: Bruun Rule Assumes 1. Profile shape does not change with respect to the water line. 2. The sand volume in the profile must be conserved. y = R = S W h + B Where y = -R = Horizontal shoreline recession S = Sea level rise W = Width of the active beach profile h = Depth of closure B = Berm height 10 Adapted from: Dean, R.G and Dalrymple, R.A., 2002. Coastal Processes with Engineering Applications. Cambridge: Cambridge University Press, 475 p.
Sea Level Rise Shoreline Recession: Dean Equilibrium Profile Assumes 1. Beach shaped to equilibrium by steady state sea conditions 2. Erosion 2-dimensional mass balance of accretion & erosion 3. Profile shape given by h = Ax m Where h = stillwater depth above the equilibrated profile x = the horizontal distance from the shoreline m = exponent to fit A = Dimensional scale parameter related to sediment 11 Adapted from: Dean, R.G and Dalrymple, R.A., 2002. Coastal Processes with Engineering Applications. Cambridge: Cambridge University Press, 475 p.
Navarre Beach Santa Rosa County 12
Navarre Beach Santa Rosa County July 18, 2005 13
Navarre Beach Santa Rosa County Initial Construction: 2.95 Mcy 4.1 miles 136 cyds/ft 2006 14
Navarre Beach Santa Rosa County R-200 15 Photo From: Google Earth
Navarre Beach - Santa Rosa County R-200 16
Santa Rosa County Navarre Beach 17
Renourishment Volume (cyds/ft) Effectiveness of Beach Nourishment in Response to Sea Level Rise 70 65 60 55 50 45 40 46.4 Navarre Beach - Santa Rosa County Nourishment - future needs based on 8 year cycle to offset longshore sediment transport gradient & sea level rise 2006 Fill Density = 136 cyds/ft for 8-year cycle 2015 Fill Density = 73 cyds/ft for 8-year cycle 48.6 50.8 53.0 54.8 41.09 41.53 42.41 42.86 42.86 43.74 44.18 44.62 45.50 45.50 57.0 59.2 61.4 63.2 65.4 35 30 2020 2030 2040 2050 2060 2070 2080 2090 2100 USACE Int. USACE High 18
Height above MSL (ft) Effectiveness of Beach Nourishment in Response to Sea Level Rise Navarre Beach - Santa Rosa County No Action - Intermediate Sea Level Change - 2065 15.0 12.5 10.0 7.5 5.0 2.5 0.0-2.5-5.0-300 -250-200 -150-100 -50 0 50 Distance from MSL (ft) R-200 40 122 Equilibrium Profile Zero Int Bruun Dean 19
Height above MSL (ft) Effectiveness of Beach Nourishment in Response to Sea Level Rise Navarre Beach - Santa Rosa County No Action - High Sea Level Change - 2065 15.0 12.5 10.0 7.5 5.0 2.5 0.0-2.5 268-5.0-300 -250-200 -150-100 -50 0 50 Distance from MSL (ft) R-200 112 Equilibrium Profile Zero High Bruun Dean 20
Height above MSL (ft) Effectiveness of Beach Nourishment in Response to Sea Level Rise 15.0 12.5 10.0 7.5 5.0 2.5 Navarre Beach - Santa Rosa County Seawall by 2065 Seawall at 30 ft. seaward of house 0.0 214-2.5 174-5.0 103-300 -250-200 -150-100 -50 0 50 Distance from MSL (ft) R-200 Zero Int High Equilibrium Profile USACE Int. USACE High 21
22 Effectiveness of Beach Nourishment in Response to Sea Level Rise
Lovers Key - Lee County We are here! Lovers Key R-219 23
April 23, 2012 24
Lovers Key Lee County Initial Construction: 533,385 cy 1.1 miles 90cy/ft 2004 25
Lovers Key - Lee County R-219 26
XLovers Key Lee County 27
Lovers Key Lee County R-219 28
Renourishment Volume (cyds/ft) Effectiveness of Beach Nourishment in Response to Sea Level Rise 90 80 70 60 Lovers Key - Lee County Nourishment - future needs based on 8 year cycle to offset longshore sediment transport gradient & sea level rise 2004 Average Fill Density = 90.0 cyds/ft for 8 year cycle 2014 Average Fill Density = 58.1 cyds/ft for 8 year cycle 64.2 66.8 69.4 57.9 58.4 59.0 71.5 74.1 60.0 60.0 76.7 79.3 81.4 84.1 86.7 61.0 61.6 62.1 62.6 63.1 50 2020 2030 2040 2050 2060 2070 2080 2090 2100 USACE Int. USACE High 29
Height above MSL (ft) Effectiveness of Beach Nourishment in Response to Sea Level Rise 8.00 6.00 4.00 2.00 0.00-2.00-4.00-6.00 Lovers Key - Lee County No Action - Intermediate Sea Level Change - 2065-8.00-200 -100 0 100 75 Distance from MSL (ft) R-219 34 Equilibrium Profile Zero Int Bruun Dean 30
Height above MSL (ft) Effectiveness of Beach Nourishment in Response to Sea Level Rise Lovers Key - Lee County No Action High Sea Level Change - 2065 8.00 6.00 4.00 2.00 0.00-2.00-4.00-6.00 R-219 Estero Bay 97 199-8.00-400 -300-200 -100 0 100 Distance from MSL (ft) Equilibrium Profile Zero High Bruun Dean 31
Height above MSL (ft) Effectiveness of Beach Nourishment in Response to Sea Level Rise Lovers Key - Lee County Seawall by 2065 Seawall at 30 feet seaward of tram house 8.00 6.00 4.00 2.00 0.00-2.00-4.00-6.00 50-8.00-100 0 100 Distance from MSL (ft) R-219 Zero Int High Equilibrium Profile USACE Int. USACE High 32
South County St. Lucie County 33
34 Effectiveness of Beach Nourishment in Response to Sea Level Rise
Ft. Pierce Inlet South County St. Lucie County Martin County Line Initial Construction: 682,500 cy 3.4 miles 38.5cy/ft 2013 35
South County - St. Lucie County Normandy Beach Park R-101 36
South County - St. Lucie County R-101 37
South County - St. Lucie County 38
Renourishment Volume (cyds/ft) Effectiveness of Beach Nourishment in Response to Sea Level Rise 39 50 45 40 35 30 25 20 15 10 5 17.9 South County - St. Lucie County Nourishment - future needs based on 10 year cycle to offset longshore sediment transport gradient & sea level rise 2013 Fill Density = 38.5 cyds/ft for 10-year cycle 22.2 26.0 30.4 34.2 38.5 9.8 10.3 11.4 12.5 13.6 14.1 41.8 46.6 15.7 16.3 0 2020 2030 2040 2050 2060 2070 2080 2090 2100 USACE Int. USACE High
Height above MSL (ft) Effectiveness of Beach Nourishment in Response to Sea Level Rise South County - St. Lucie County No Action - Intermediate Sea Level Change - 2065 20.00 15.00 10.00 5.00 R-101 0.00-5.00-10.00-200 -150-100 -50 0 50 100 85 36 Distance from MSL (ft) Equilibrium Profile Zero Int Bruun Dean 40
Height above MSL (ft) Effectiveness of Beach Nourishment in Response to Sea Level Rise South County - St. Lucie County No Action High Sea Level Change - 2065 20.00 15.00 10.00 5.00 R-101 0.00-5.00 95 183-10.00-200 -150-100 -50 0 50 100 Distance from MSL (ft) Equilibrium Profile Zero High Bruun Dean 41
Height above MSL (ft) Effectiveness of Beach Nourishment in Response to Sea Level Rise 20.00 15.00 10.00 5.00 South County - St. Lucie County Seawall by 2065 Seawall at 30 feet seaward of house R-101 0.00-5.00 11-10.00-250.00-200.00-150.00-100.00-50.00 0.00 50.00 100.00 Distance from MSL (ft) Zero Int High Equilibrium Profile USACE Int. USACE High 107 71 42
Summary Shoreline Recession (feet / year) Florida Shoreline Recession Navarre Beach SRC 1 Lovers Key Lee 2 South County SLC 3 Int. High Int. High Int. High Bruun 0.81 2.24 1.49 3.97 0.72 1.91 Dean 2.45 5.35 0.67 1.94 1.70 3.65 Historic 1.0 4.4 0.56 1: Historic based on 1970 2008 surveys 2: Historic based on 1972 2008 surveys 3: Historic based on 1972 2006 surveys 43 Historic data from: Absalonsen, L. and Dean, R. G., 2010. Characteristics of the Shoreline Change Along the Sandy Beaches of the State of Florida: An Atlas.
Summary Alternative Protection Preserve Land Recreational Beach Habitat Beach Fill Classic Beach Management Objectives Yes Yes Yes Yes limited by Design MHWL fluctuates beach width fluctuates habitat fluctuates Retreat Seawall No No Yes Somewhat "demolished/ relocated" MHWL recedes width same & migrates loss of upland habitat Yes Somewhat No No limited by Design landward of seawall beach width diminishes loss of beach habitat 44
Conclusions Sea level change is estimated to rise 0.36 feet to 2.84 feet in Florida over the next 50 years. Over the next 50 years, fill quantities needed to offset sea level rise are within range of historical values. Beach nourishment is the only viable alternative to meet classic Beach Management Objectives. A better understanding of the effects of sea level rise upon beach nourishment is warranted. 45
Thank you Questions?