Changes in Beach Profile and Grain Size after Beach Renourishment

Kevin Bodge, PE PhD Krista Egan, EI olsen associates, inc. and Mike McGarry Brevard County Natural Resources Mgt. Dept. Changes in Beach Profile and Grain Size after Beach Renourishment February 2018 Beach Preservation Tech. Conf.

How does beach profile shape change after a beach renourishment event? How does sand grain size change across the profile after a beach renourishment event? We ll contrast Pre- and Post-Project Conditions and first 2 years after a renourishment.

Brevard County, Florida Merritt Island Banana River CCAFS Sand Bypassing North Reach CSI Offshore Borrow Area CSII Shore Protection Project Atlantic Ocean Patrick AFB South Reach

Sand Grain Size varies across the Natural Beach Beach Profile 12 8 4 0-4 -8-12 -16-20 -24-28

Sand Grain Size varies across the Natural Beach Offshore Beach Nourishment Sand Brevard Native Beach* Median Sand Size (1995 2003) Beach Profile CSII *Cape Canaveral Air Station

Sand Grain Size Distribution

Canaveral Shoals II offshore sand

The existing post project sand matches the pre project sand by depth zone 2013 Samples (3 8 yrs post renour) Native Berm (pre project) Canaveral Shoals II offshore sand BERM

The existing post project sand matches the pre project sand by depth zone 2013 Samples 3 8 yrs post renour. Native Intertidal (pre project) INTER TIDAL

The existing post project sand matches the pre project sand by depth zone Native Subtidal (pre project) 2013 Samples 3 8 yrs post renour. SUB TIDAL

EXPECTED CHANGE IN SAND SIZE? OFFSHORE MIGRATION FINER SAND COARSER BERM AFTER EQUILIBRATION?

Beach Profiles Cocoa Beach R 36 Pre Nourishment (1972 2000)

Beach Profiles Post Nourishment (2001 2012) Cocoa Beach R 36 Pre Nourishment (1972 2000)

Beach Profiles Composite Profiles N 3 rd St to S 11 th St R 33 to R43 Pre Nourishment (2000/01)

Beach Profiles Post 2005 Nourishment (May 2005) Composite Profiles N 3 rd St to S 11 th St R 33 to R43 Pre Nourishment (2000/01)

Beach Profiles May 2012 (7 Yrs Post Nour.) Post 2005 Nourishment (May 2005) Composite Profiles N 3 rd St to S 11 th St R 33 to R43 Pre Nourishment (2000/01)

What happens immediately after beach renourishment construction? We examined: Beach profiles: 6 nourished and 3 non-nourished. Sand grain size at 6 depths along each profile at pre-construction and 0-, 3-, 6-12-, and 24-months post-construction. o 54 beach profile surveys, and o 324 sand samples

Beach Fill Areas x xxxxx x xxxxx x xxxxx x xxxxx x xxxxx x xxxxx North Reach Nourished Profiles (2013-14) Nourished (2014) Control (No Fill) Sand Samples x x x 2013 14 RENOURISHMENT (Brevard County) x xxxxx Control Profiles (No Fill) x xxxxx x xxxxx South Reach

Beach profiles shifted to Mean High Water alignment Control 0 MONTHS Nourished Control 3 MONTHS Nourished COMPOSITE PROFILES

Nourished 6 MONTHS Control Control 12 MONTHS Nourished COMPOSITE PROFILES

Nourished 24 MONTHS Control COMPOSITE PROFILES

0 MONTHS 3 MONTHS NOURISHED 6 MONTHS 12 MONTHS 24 MONTHS CONTROL

Elevation (ft, NAVD88) +7.5' MSL +3' MSL -1.5' MSL -10.5' MSL Elevation (ft, MSL) BEACH SLOPE ANALYSIS ZONES

Elevation (ft, MSL) NR SR SLOPE ANALYSIS: BERM CONTROL Steeper

Elevation (ft, MSL) NR SR SLOPE ANALYSIS: INTERTIDAL Steeper

Elevation (ft, MSL) NR SR SLOPE ANALYSIS: SUBTIDAL Steeper

Elevation (ft, MSL) Nourished Control SLOPE ANALYSIS: BERM

Elevation (ft, MSL) Nourished Control SLOPE ANALYSIS: INTERTIDAL

Elevation (ft, MSL) Control Nourished SLOPE ANALYSIS: SUBTIDAL

Elevation (ft, NAVD88) +7.5' MSL -9' MSL Elevation (ft, MSL) SURF ZONE WIDTH

Elevation (ft, MSL) SURF ZONE WIDTH

SEABED SAND SAMPLES

R 36 GRAIN SIZE DISTRIBUTION +3 MSL R-36 230 14 7 25 45 80 170 18 10 35 60 120 200 230 7 45 80 170 25 14 10 60 120 200 35 18 230 7 45 25 14 170 80 35 10 60 18 200 120 14 7 25 45 170 230 80 18 10 35 60 200 120 230 7 170 14 80 45 25 10 18 120 35 200 60 230 14 25 7 170 80 45 18 35 10 200 120 60 14 25 45 80 230 170 18 35 7 120 60 10 200 7 45 80 230 170 14 25 10 60 120 200 18 35 24 mos. 0 months Beach Fill Beach Fill Profile

Beach Fill Profile GRAIN SIZE VS. ELEVATION

Control Profile GRAIN SIZE VS. ELEVATION

MEAN GRAIN SIZE Nourished BERM Control Nourished +3 MSL Control

MEAN GRAIN SIZE Nourished -3 MSL Control Nourished -6 MSL Control

MEAN GRAIN SIZE Nourished -9 MSL Control Nourished -12 MSL Control

Summary Profiles Post-project beach profile conforms to native pre-project profile, except for steeper beachface slope (as expected from restoration of eroded beach). Negligible difference in average beach profile shape between nourished and non-nourished, at 0- to 24- months. Change in nourished beach slopes similar to or lesser than non-nourished profiles from pre- to 12- to 24-months. Temporal changes in profile slope and surf zone width similar between nourished and non-nourished profiles. Surf zone widths increasingly converged at 12- to 24-months.

Summary - Sand Existing post-project sand matches native sand, by depth. Grain size at nourished berm slightly increased at 0-6 months, returned to pre-renourishment within 12-24 months. Little net change in grain size at/below MHW..changes were less than non-nourished profiles. Negligible changes below -9 ft MSL anywhere. Temporal variations in grain size are significant -- mostly greater at non-nourished profiles, and obscure trends.. though there is limited indication of increasing coherence at 12- and 24-months post-construction.