Storm Scenario Impacts on Barrier Island Systems
Rangley Mickey
Cherokee Nation Technology Solutions
contracted to U.S. Geological Survey
600 4th Street South
St. Petersburg, FL 33701
727-502-8115
rmickey@usgs.gov
Poster Abstract
Coastal resiliency has become a major topic in the discussion of preserving important coastal habitats,
for both humans and wildlife. This topic applies to all coastal zones but it is particularly significant for
barrier island systems that contain residential properties, recreational areas, and important wildlife
habitats. The Chandeleur Islands off the coast of eastern Louisiana, part of the Breton National Wildlife
Refuge, were set aside in the early 1900s as an essential refuge and breeding ground for migratory birds,
such as the endangered piping plover and populations of brown pelicans. This barrier island system has
experienced an increasing amount of subsidence and erosion over the past century due to lack of
sediment availability, rising sea level, and major storm impacts. This area was anthropogenically
impacted by the 2010 Deepwater Horizon oil spill, at which time a 2 meter high sand berm was
constructed along the gulf shoreline to prevent oil from reaching the island. The construction of this
berm provided a natural laboratory to observe changes in island morphology on short time scales,
mostly due to storm events. The observed changes include spatially varying overwash and breaching
along the both the berm, and portions of the island where no berm was constructed. This provides a
comparison of island evolution over a range of conditions that can inform our understanding of coastal
change processes along barrier island systems.
In this work the hydrodynamic and morphodynamic numerical model Xbeach is used to investigate how
varying storm scenarios impact this newly formed berm along the Chandeleur Islands and adjacent areas
of the island chain that were not protected by a berm feature. The Xbeach model grid was generated
using satellite imagery to define a footprint of the as-built berm and then generating a 2 meter high
berm within the footprint area using a Gaussian curve. Using archived National Data Buoy Center data
collected at buoy 42007 (located northeast of the barrier island) from 1996 to 2007, a total of 10
scenario bins were developed based on wave height and storm duration to represent hypothetical storm
conditions. By executing these different model scenarios, changes in berm morphology (i.e. area, width,
and height) were examined and compared to aerial photographs and LIDAR data to determine the
effectiveness of scenario binning as well as model accuracy. The application of running these scenarios
consecutively in different combinations can also be used to determine the resiliency of the island chain
and berm over a series of storm events. Due to the overall simplicity of this binning technique, our
approach could be applied to most barrier island systems, particularly those with proposed or on-going
restoration projects, where historical data and island imagery are available. Similar investigations using
this technique could provide an essential tool for government agencies and stakeholders involved in
barrier island restoration and preservation.
Biography
The presenter, Rangley Mickey, received a B.S. in Biology from the University of North Carolina at
Charlotte in 2009 and a M.S. in Coastal Marine and Wetland Studies from Coastal Carolina University in
2013. His master’s research included spatial and temporal sediment grain size analysis, GUST erosional
microcosm experiments, and numerical modeling of hydrodynamic and sediment transport processes
across the Louisiana-Texas shelf. Rangley Mickey is currently employed by Cherokee Nation Technology
Solutions as a contractor to the United States Geological Survey. His current research focuses on using
numerical models to investigate how storm events impact barrier island systems.