Satellite-Derived Barrier Response and Recovery Following Natural and Anthropogenic Perturbations, Northern Chandeleur Islands, Louisiana

Abstract

The magnitude and frequency of storm events, relative sea-level rise (RSLR), sediment supply, and anthropogenic alterations drive the morphologic evolution of barrier island systems, although the relative importance of any one driver will vary with the spatial and temporal scales considered. To explore the relative contributions of storms and human alterations to sediment supply on decadal changes in barrier landscapes, we applied Otsu’s thresholding method to multiple satellite-derived spectral indices for coastal land-cover classification and analyzed Landsat satellite imagery to quantify changes to the northern Chandeleur Islands barrier system since 1984. This high temporal-resolution dataset shows decadal-scale land-cover oscillations related to storm–recovery cycles, suggesting that shorter and (or) less resolved time series are biased toward storm impacts and may significantly overpredict land-loss rates and the timing of barrier morphologic state changes. We demonstrate that, historically, vegetation extent and persistence were the dominant controls on alongshore-variable landscape response and recovery following storms, and are even more important than human-mediated sediment input. As a result of extensive vegetation losses over the past few decades, however, the northern Chandeleur Islands are transitioning to a new morphologic state in which the landscape is dominated by intertidal environments, indicating reduced resilience to future storms and possibly rapid transitions in morphologic state with increasing rates of RSLR.

Undeveloped and developed phases in the centennial evolution of a barrier-marsh-lagoon system: The case of Long Beach Island, New Jersey

“…in the literature (see Supplementary Tables S3, S4). Moreover, the mechanics of the numerical model used to describe the dynamics of these boundaries are consistent with several recent studies on different barrier islands along the U.S. East and Gulf Coasts (e.g., Walters et al, 2014;Rogers et al, 2015;Bernier et al, 2021). For instance, barrier width can exert a primary control over the magnitude of overwash fluxes (Figure 5F), which not only drive barrier landward migration (Figure 5B) but also are an important sediment source for backbarrier marshes (Figure 5C), allowing lower rates of erosion in comparison to isolated marshes (Figures 5D).…”

Editorial for Special Issue: “New Insights into Ecosystem Monitoring Using Geospatial Techniques”

“…The goal of the study of J. C. Bernier et al [14] was to provide a comprehensive analysis of recent landscape-scale changes along the northern Chandeleur Islands using a consistent dataset and methodology to better understand temporal and spatial variability in barrier response to natural and anthropogenic disturbances over the past few decades. The results presented in this study demonstrate that automated thresholding algorithms can be applied to multiple spectral indices derived from medium-resolution Landsat satellite imagery to rapidly delineate land-cover classes and barrier-island extents at the landscape scale.…”

A Methodology for National Scale Coastal Landcover Mapping in New Zealand

“…Despite the widespread use of pixel-based landcover classification in remote sensing, applying these methods for coastal research has remained limited to a small number of studies that have used pixel landcover classification to quantify sediment supply and vegetation cover to assess coastal change for barrier islands at regional scales [31,32]. A global approach [24] estimated that 31% of the world's ice free coasts are sandy beaches using supervised image classification techniques, and [33] were able to estimate beach width by comparing vegetation areas with IW position.…”