Initial Morphological Evolution of an Artificial Intertidal Berm at Perdido Key
Beach, Florida
Ping Wang and Katherine E. Brutsche
Department of Geology, University of South Florida, Tampa, FL 33620, pwang@usf.edu
A nearshore berm was placed in the intertidal and swash zone of Perdido Key, Florida in January
2012. A pre-construction survey and approximately bi-monthly post-construction surveys are
conducted and analyzed to investigate morphological evolution of the berm during the first eight
months after construction. The Perdido Key berm is rather unique in that it is placed largely in
the intertidal zone with the elevation of the flat berm crest at +3ft NAVD88, or just above the
spring high tide level and 3 ft below the typical elevation of the back beach. A directional wave
gage was deployed approximately 600 m offshore of the middle of the berm project. Intensive
sediment sampling was conducted before and immediately after the berm construction to
compare the sediment characteristics of placed sand and the native sand.
The initial 3-month data suggest that the Perdido Key berm nourishment has exhibited
substantial morphological changes since the placement of the berm in December 2011-January
2012. Generally, the berm nourishment widened the beach (at +3 ft NAVD88 elevation)
approximately 200 ft. Two months after placement, the berm width decreased by approximately
50-100 ft. A natural berm was developed over the artificial berm placement. The growing
natural berm has an elevation of 4 ft two months after the placement, or one foot above the
constructed berm. Considerable longshore spreading of the artificial berm was measured toward
the east and the Pensacola Pass, where the sand were dredged. Tidal current in the vicinity of the
inlet seems to play a significant role in transporting sediment toward the inlet, based on field
observations during the survey. Longshore spreading toward the west, in the direction of
documented net longshore transport, is not significant during the first two months.
Frequent winter storms were captured by the nearshore wave gage. Relationship between berm
evolution and incident wave energy is being analyzed. Initial analyses of the wave data indicate
several energetic winter storms during the first two months post construction, with significant
wave height exceeding 2 m about 600 m from shoreline. Initial analyses of sediment samples
suggest that the placed sand is finer than the native sand.
The full presentation will include the first eight-month performance of the artificial berm. The
performance of the berm will be related to in situ measured incident wave conditions. Influence
of sand size to the berm performance will also be examined.
Biography of the Presenter
Ping Wang is the director of the Coastal Research Laboratory and an Associate Professor at the
Department of Geology at the University of South Florida. Wang obtained his Ph.D. in Coastal
Geology from the University of South Florida in 1995. Wang’s research interest includes:
coastal sedimentary processes, nearshore sediment transport, nearshore wave and current
dynamics, coastal morphodynamics, coastal engineering and management, numerical modeling
of coastal environments. Impact of the BP oil spill to beach environments is the new “research
adventure” by Wang and his research team. Wang and Dr. Nicole Elko co-led the field trip for
the 2009 ASBPA national conference.