Shoreline and Shoreface Assessment of Galveston Island: Seamless shoreface
surface analysis merging land-based Laser surveying with ultra-high resolution
swath bathymetry
Juan Moya1, Timothy M. Dellapenna2, Joseph Carlin2&3, Cris Weber1, and Rhonda
Gregg4
Summary
In 2014, the Atkins Coastal Group (Atkins) and the Coastal Geosciences Group (CGC) at
Texas A&M University, Galveston campus (TAMUG) began one of the most
comprehensive beach-shore face monitoring programs in the nation. First, the CGC team
has conducted a series of beach profies and side scan sonar and swath bathymetry surveys
of Galveston Island, beginning in 2001, with a complete mosaic merged together for preHurricane Ike (2008) and post-Hurricane Ike (2010-2011 surveys) data series. This
project extends the time series from 2001 through 2014. The post-Hurricane Ike beach
profiles revealed dramatic retreat of the beach, with up to 53 m (174 ft) of lateral beach
retreat, up to 1.7 m (5.5 ft) of vertical erosion of the beach and an estimated loss of
between 2-3 x 106 m3 (2.6-4 x 106 yd3) of sand. The side scan sonar mosaics revealed
substantial changes to the shore face and inner shelf of the island, including the formation
of scoured channels and pits on the shoreface and the formation of large sand bars in 7-10
m water depth, trapped seaward of the “fairweather” depth of closure.
In the next four years, Atkins will conduct land-based high-density laser surveys of the
entire dry beach of the island, from the landward toe-of-dune line to the water line and
collect beach profiles to wading depth every 305 m (1000 ft) along the 28.2 miles of
beach. In addition, CGC will conduct swath bathymetry surveys using a Teledyne
Benthos C3D® bathymetric side scan sonar system, from 2 m of water depth to 4 m,
every year for the entire length of the island (from the south jetty to San Luis Pass).
Every other year, they will conduct a survey from 2 m to 10 m (2014 and 2016). The
wave base/depth of closure for non-hurricane conditions is estimated to be approx. 6-7 m
of water depth, so the full surveys will extend beyond non-hurricane (fair weather) depth
of closure. The laser survey, wading depth surveys and swath bathymetry data will be
merged into one seamless and continuous point-cloud that may be used to create a digital
surface, available for input into any digital platform, such as Arc GIS or Surfer.
These surveys will provide a comprehensive data for the analysis of the shoreface,
providing the best geologic data available for beach related processes to be used by
coastal managers, monitors, as well as for researchers. Continuing this time series
through this beach monitoring program, the data will allow for the continual monitoring
of the recovery or general trends of the shoreface since Hurricane Ike, providing a
baseline dataset to assess future storm impacts and further understanding of the
geological framework of the barrier island system and the hydrodynamic process needed
to design engineering projects on the Gulf shorelines.
1
Freese and Nichols, Inc. 10431 Marodo Circle, Building 5, Suite 300, Austin, Texas 78759,
ph: 512-617-3134
2
Departments of Marine Science and Oceanography, Texas A&M University, Galveston,
TX.
3
Department of Geological Sciences, California State University, Fullerton, Fullerton,
CA.
4
Shelmark Engineering, LLC. 921 FM 517 Road East, Dickinson, TX 77539.
Presenter Biography
Dr. Juan Moya serves as a senior scientist for Freese & Nichols. He is the lead in Coastal
Restoration with more than 26 years of experience in environmental project management,
coastal and terrestrial geology, geomorphology, habitat restoration, mapping of surface
processes, and conducting feasibility studies for environmental and natural resource
projects for coastal areas. His experience includes serving as a coastal geologist/project
manager for the Texas General Land Office (GLO) for more than 11 years, where he
conducted sediment investigations as well as geologic studies and managed projects for
coastal erosion planning and response.