University of Texas at Austin

THSCMP - Port Aransas High School

Beach and Dune Monitoring on Mustang Island
Tiffany Caudle and Jeffrey Paine

Port Aransas students collect data at three profile locations on Mustang Island: MUI01 near Horace Caldwell Pier, MUI02 in Mustang Island State Park, and MUI03 (Fig. 1). Port Aransas High School has been measuring these profiles since 1999.

figure 1
Figure 1. Location map of Port Aransas High School monitoring sites.

The beach-monitoring activities of Port Aransas High School students have also provided beneficial information regarding the beach and dune system on Mustang Island. The dune system on Mustang is healthy, with tall (>3 m), wide foredunes along most of the island. The only breaks in the foredune system are at beach-access points and washover features. On Mustang Island, beaches are regularly scraped to remove seaweed from the forebeach. The sand and seaweed removed from the berm and forebeach are regularly placed at the seaward base of the foredunes. Since the beginning of the coastal monitoring program, Port Aransas students have been monitoring the growth of the foredune system at their profiling sites. Figure 2 is an example of expansion of the foredune at MUI01 near Horace Caldwell Pier in Port Aransas. Note that the width of the dune increased between 2001 and early 2012, although the shoreline remained in a relatively stable position.

Figure 2

Figure 2. Foredune expansion at MUI01 on Mustang Island.

When Port Aransas students arrived to collect profile data in October 2012, a large part of the dune face had been excavated (Fig. 3) for beach-maintenance purposes. Students documented that sand was replaced in the foredune by May 2013 and that the vegetation line has been re-established at the toe of the dune. The dune has again been excavated since the 2014–2015 academic year. The current width of the foredune is narrower and the volume of sand in the profile is significantly less than when THSCMP began monitoring in 1999. Also the crest of the foredune is lower in elevation because there is no vegetation on the crest. The dune crest is no longer stabilized at this location and sand is being carried away by the wind. The excavated area is slowly being filled in. Notice the increase in sand at the base of the dune face on the latest profile plot (Fig. 3).

Dune Excavation

Figure 3. Excavated dune profile and photos at MUI01 on Mustang Island.