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Insight Into the Physical Signatures of Marsh Erosion

April 05, 2018
3:00 pm - 4:00 pm

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Dr. Thomas Huff
Department of Ecosystem Science & Management
Postdoctoral Research Associate

Abstract:
Salt marshes along the Galveston Bay coast experience a high degree of edge erosion caused by wave impact. Meters of marsh edge retreat per year lead to a significant loss of ecosystem services over time. The goal of this study was to determine the minimum wave height contributing to marsh erosion. A total of six marsh soil cores were extracted from Galveston Bay and placed in the Haynes Lab wave basin. Regular waves with a 2 second period and heights of 1 cm, 4 cm, 8 cm, 12 cm, 16 cm, and 20 cm were used to impact the marsh core surface. Wave staffs and Acoustic Doppler Velocimeters (ADV) were used to measure the height and water velocity of the impacting waves. The cores were then measured using a Terrestrial Lidar Scanner (TLS) at 1 mm point spacing. The scans were imported into Cloud Compare software to measure erosion at each LiDAR point.
This analysis showed that at even low wave heights (4 cm) that erosion was still measurable. From 8 cm wave heights to 20 cm wave heights irregularities were seen in the vertical erosion profiles. These deviations from the trend were caused by the wave form. Increased erosion was observed on waves that had a plunging wave impacting the core surface. Higher water levels were also shown to reduce erosion as less erosion occurred below the water line compared to above.
This experiment showed that erosion is happening at very small wave heights with only approximately 1 cm wave heights causing negligible erosion. This could indicate that a high frequency of small waves could have a similar long term impact as a low frequency of large waves.

Bio:
Thomas Huff has been at Texas A&M University for 4.5 years, where he received a PhD in Ecosystem Science and Management in August of 2017. During his doctorate, his work ranged from marsh restoration projects along the Texas coast, to creating better ways of modeling wind tides throughout the Gulf of Mexico and U.S. Atlantic Coast. This included G/S analysis and hydro/ogic modeling. The Magnolia Beach marsh project received the Ecological Excellence Award from the State of Texas. Before TAMU, he finished a Bachelor’s of Science degree in Wildlife Conservation and Management Sciences from TAMU- Commerce. He currently works as a Postdoctoral Researcher in the Costa/ Management Laboratory run by Dr. Rusty Feagin in the Department of Ecosystem Science and Management. He continues to run and manage a 7 meter wave tank that he designed and built during his PhD in addition to conducting field research at several locations along the Texas coast. His current research interest are focused toward marsh resilience, sea level rise’s effects on coastal ecosystems, and improving wind tide flood predictions.

Contact: Michael Bishop @ michael.bishop@tamu.edu

Details

Date:
April 5, 2018
Time:
3:00 pm - 4:00 pm

Venue

Eller O&M Bldg., Room 807