Title

Assessing the impact of subaerial vegetation to mitigate coastal erosion during extreme storms

Author

Felix Groetsch, University of Rhode IslandFollow

Date of Award

2022

Degree Type

Thesis

Degree Name

Master of Science in Ocean Engineering

Department

Ocean Engineering

First Advisor

Annette Grilli

Abstract

In a changing climate, protecting developed coastal areas becomes more challenging, as they are strongly affected by increasingly severe storms and rising sea levels. This study aims to assess the vegetation's role in protecting New England coastal communities. Using the morphodynamic model XBeach, a static and a dynamic modeling approach are implemented to (1) improve the mapping of published vegetation coverage data, (2) calibrate the XBeach model, (3) investigate the parameterization of subaerial vegetation in the model, and (4) assess how coastal vegetation management policy influences the mitigating effect of vegetation for the selected site.

A comprehensive literature review and an interview with two Rhode Island National Wildlife Refuge Complex wildlife biologists are conducted, providing a theoretical and empirical foundation. The simulated responses of the barrier beach system to Hurricane Sandy coupled with 0ft and 1ft of sea-level rise are evaluated by testing their sensitivity to the bed roughness associated with the land cover type. An improved high-resolution classification focusing on the spatially varying bed roughness is generated based on the assessment of published land cover classifications.

The calibration and model results exhibit a strong dependency on the facua parameter. The dynamic roughness model improves model results by simulating natural processes more realistically than the static approach. The resolution, accuracy, and level of detail regarding the bed roughness of land cover classifications influence the model results and can lead to significant local differences. The XBeach model is sensitive to bed roughness values, and using highly detailed land cover classification improves simulations. The results demonstrate the fundamental mitigating effect of vegetation. When completely removing barrier beach vegetation, the prevailing erosion nearly doubles. In contrast, local vegetation management policies affect the sediment distribution at the shoreline but do not significantly increase erosion and accretion rates. Therefore, preserving the existing vegetation is essential to maintain the vegetation's mitigating effect.

Recommended Citation

Groetsch, Felix, "Assessing the impact of subaerial vegetation to mitigate coastal erosion during extreme storms" (2022). Open Access Master's Theses. Paper 2239.
https://digitalcommons.uri.edu/theses/2239