Port Aransas High School

School Website: https://www.paisd.net/35330

2022-2023 field trip data: PortAransasHS2022-23v2.pdf

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Beach and Dune Monitoring on Mustang Island by 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 have 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 provided beneficial information about the beach and dune system on Mustang Island. The dune system on Mustang Island 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. Since the beginning of the coastal monitoring program, Port Aransas students have been monitoring the growth of the foredune system at all three of their profiling sites (Figs 2, 3, and 4).

Beach maintenance practices vary along the island and have changed over time, which the students have documented through their data. Several beaches on Mustang Island, particularly within the City of Port Aransas boundaries, are regularly scraped to remove seaweed (Sargassum) from the forebeach. The MUI01 site was dune notched in 2012 and 2015, a beach beach-maintenance practice where sand is removed from the dune and replaced with sargassum and sand scraped from the beach over time (Fig. 2). MUI01 also has shore-parallel bollards that have been installed to confine vehicles to the upper portion of the backbeach. The placement of these bollards has restricted further seaward advancement of the foredune complex and the vegetation line by maintaining a fixed location of the Mustang Island Beach Road starting at the toe of the dune (Fig. 2). The beach road has also impacted the seaward extent of dune growth and vegetation line movement at MUI03 (Fig. 3). The beach maintenance practices and the impacts of the fixed position of the Mustang Island Beach Road will continue to be monitored by Port Aransas students at MUI01 and MUI03 and compared with the natural processes that occur at MUI02 in Mustang Island State Park (Fig. 4). Minimal beach maintenance is performed within the state park boundaries, only to keep the beach access points open.

Figure 2

Figure 2. Student monitoring data from MUI01 on Mustang Island. (A) Beach profile data from April 2001 through April 2023 showing expansion of the dune width until dune notching in 2012 and more severely in 2016. The dune system has been filled in but is no longer moving seaward due to the location of the Beach Road. (B) Photos showing the changes to the dune at MUI01 on September 20, 2005, October 25, 2012, and April 26, 2023. The 2012 photo shows the notch in the dune where sand was removed.

Figure 3

Figure 3. Student monitoring data from MUI03 on Mustang Island. (A) Beach profile data from November 2000 through April 2023. The profile plot shows seaward expansion of the dune system through 2010. The Beach Road on the backbeach has stopped the expansion of the dunes creating a fixed position of the dune toe with minimal change between 2013 and 2023. (B). Photos from October 2, 2001 and April 25, 2018 looking north along the landward most dune crest on the beach profile. (C) Photo from November 15, 2021 looking north along the Beach Road. 

Figure 4

Figure 4. Student monitoring data at MUI02 in Mustang Island State Park. (A)Beach profile data and (B) GPS-mapped vegetation line positions between November 2000 and April 2023. The students have been documenting the seaward migration of the shore and vegetation lines as well as the growth of the dune system through 2020. The seaward most coppice dunes had been eroded and the vegetation line had moved landward during the April 2022 field trip. More erosion occurred during the 2022-23 academic year. (C) Photo looking north along the landward most dune crest on the beach profile on May 4, 2017.

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