Coastal Dune Vulnerability Assessment: Integrating Adaptation Information into Dune Management System in South Padre Island

by Johnson O. Ajedegba; Tushar Sinha and Kim D. Jones

Posted on 2021-06-26 DOWNLOAD PDF

Abstract

A new integrated dune vulnerability assessment model was evaluated in this study to quantify the risk levels of dune vulnerability parameters for development of a dune management system. The methodology used dune exposure criteria such as marine, aeolian and anthropogenic impacts; dune sensitivity criteria such as geomorphological and vegetation conditions; and community adaptation programs to estimate the overall dune vulnerability along a 20 km coastal stretch in South Padre Island (SPI), Texas, USA. Analytical hierarchy process (AHP) was used to prioritize and select site-specific parameters from each criterion. Using remote sensing techniques with high resolution aerial images and digital elevation model, dune vulnerability parameters (including vegetation cover and dune elevation) were estimated. Results showed that dune geomorphology (e.g. low elevation and fragmentation) and vegetation characteristics (e.g. low vegetation cover and lack of root spreading species) were the most significant drivers of dune vulnerability at SPI with high to very high index values. Aeolian vulnerability had 78% correlation with vegetation vulnerability indicating a synergistic benefit for adequate dune vegetation maintenance. Where robust ecological and cultural adaptation programs were implemented at a dune segment, vulnerability index decreased by 20% while a lack of adaptation programs further increased vulnerability index by 11% at other segments. A dune management system was proposed for implementation by County Parks to match a specific dune segment’s vulnerability characteristic with appropriate restoration strategy.