Monitoring tidal hydrology within saltmarsh vegetation to detect current attenuation using the Mini Buoy

Merz, Nina (2025) Monitoring tidal hydrology within saltmarsh vegetation to detect current attenuation using the Mini Buoy. MSc(R) thesis, University of Glasgow.

Abstract

Coastal zones are associated with growing populations, and with climate change increasing intensity and frequency of storms these communities are increasingly facing the threat of flooding. Saltmarshes are coastal ecosystems which are known to attenuate hydrodynamic energy thereby reducing risk for coastal populations. The incorporation of saltmarshes into coastal defence strategies is hindered by gaps in our knowledge concerning lateral saltmarsh dynamics and biophysical feedback networks. This knowledge is essential for accurately and reliably predicting the risk reduction capacity of nature-based solutions for flooding. Developing a tool for long-term hydrodynamic monitoring, quantifying the current velocity (Cv) attenuation effects of salt marsh vegetation, and understanding how plant traits can impact the Cv attenuation capacity of saltmarsh species are critical steps towards better understanding saltmarsh dynamics.

In this study, we quantified the Cv attenuation of two salt marsh species (Bolboschoenus maritimus and Phragmites australis) that are abundant in the Inner Clyde Estuary. Using a novel low-cost method (the Mini-Buoy), we monitored hydrodynamics at the edge and five meters into the vegetation at three monospecific stands of each species. Two models of the Mini Buoy (the Pendant and the B4+) were compared against each other to determine which was better suited for deployment within saltmarsh vegetation and for quantifying current attenuation. Vegetation surveys at the start, middle, and end of the growing season (May-Sep) were carried out to associate plant traits with their attenuation effect. This study found that the Pendant Mini Buoy was the better model for hydrodynamic monitoring within the vegetation canopy and for quantification of current attenuation in shallow, low-energy conditions. Also, morphological adaptations to the physical environment were observed in both B. maritimus and P. australis where slenderness of the plants increased landward of the wave-exposed seaward boundary. Between the two species, significant differences in morphology and attenuation capacity were observed. Lower stem density and FSA was consistently observed in P. australis which was also found to develop in lower hydrodynamic energy areas, suggesting that P. australis is more vulnerable to hydrodynamic forcing. Overall, B. maritimus (maximum Cv reduction of ~60%) was found to be more effective at reducing current velocities than P.australis (maximum Cv reduction of ~40%).

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Subjects: G Geography. Anthropology. Recreation > G Geography (General); G Geography. Anthropology. Recreation > GE Environmental Sciences
• Colleges/Schools: College of Science and Engineering > School of Geographical and Earth Sciences
• Funder's Name: Natural Environment Research Council (NERC)
• Supervisor's Name: Vovides, Dr. Alejandra and Bass, Dr. Adrian
• Date of Award: 2025
• Depositing User: Theses Team
• Unique ID: glathesis:2025-84871
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 07 Feb 2025 15:29
• Last Modified: 07 Feb 2025 15:29
• Thesis DOI: 10.5525/gla.thesis.84871
• URI: https://theses.gla.ac.uk/id/eprint/84871