University of Texas at Austin

THSCMP - Tidehaven Middle School

Tidehaven Middle School students collect data at MAT03 (Fig. 1). Tidehaven's fall and spring field trips are scheduled to coincide with the Beach Clean-Up at Matagorda Bay Nature Park.

figure 1
Figure 1. Location map of Tidehaven Middle School monitoring site MAT03.

Matagorda area students collect beach measurements at Matagorda Bay Nature Park. The park has two special circumstances that make this monitoring especially informative and important. Monitoring sites have been established (1) on the updrift side of the jetty at the mouth of the Colorado River and (2) at sites that allow students to compare a beach/dune system where vehicular traffic on the beach will be limited (MAT03) with adjacent areas where vehicular traffic will continue to be unrestricted (MAT01 and MAT02). Impacts of coastal structures (jetties) are critical to coastal management, and impacts of vehicles on Texas’ beaches are not well documented. Vehicular traffic was permitted on the beach adjacent to the Nature Park until 2007. Currently, this section of beach has restricted access for vehicular traffic.

During the 2009–2010 academic year, the U.S. Army Corps of Engineers began constructing a new east jetty at the mouth of the Colorado River. GPS-mapped shorelines from September 2009 and September 2012 show a 45-m seaward movement of shoreline position at MAT03 updrift of the new jetty (Fig. 2). Student data at MAT03 has shown that the new jetty on east Matagorda Peninsula has caused the shoreline to move seaward at an average rate of 11 m per year between 2009 and 2016.” 

Figure 2

Figure 2. Shoreline position change at Matagorda Peninsula.

The shoreline and vegetation line position have been continuously moving seaward and volume has been increasing at this site throughout the study period (Fig. 3). The combination of the new jetty impounding sand on the updrift side and the decreased vehicle access at MAT03 has allowed for coppice dune formation to occur on the expanded backbeach area and for new vegetation to develop without being disturbed. On the field trips during the 2015–2016 and 2016—2017 academic years, it was documented that salt marsh plants have become established on the widened backbeach area in the swales between the coppice dunes.

Figure 3

Figure 3. Changes in beach and dune volume, shoreline position, and vegetation line position at MAT03 on Matagorda Peninsula.