Controls on coastal dune morphology, shoreline erosion and barrier island response to extreme storms

C. Houser; C. Hapke; S. Hamilton

doi:10.1016/j.geomorph.2007.12.007

Home/Archive/USGS

USGS · 70000234

Controls on coastal dune morphology, shoreline erosion and barrier island response to extreme storms

C. Houser·C. Hapke·S. Hamilton

View original source ↗Export metadata ↓

Abstract

The response of a barrier island to an extreme storm depends in part on the surge elevation relative to the height and extent of the foredunes which can exhibit considerable variability alongshore. While it is recognized that alongshore variations in dune height and width direct barrier island response to storm surge, the underlying causes of the alongshore variation remain poorly understood. This study examines the alongshore variation in dune morphology along a 11 km stretch of Santa Rosa Island in northwest Florida and relates the variation in morphology to the response of the island during Hurricane Ivan and historic and storm-related rates of shoreline erosion. The morphology of the foredune and backbarrier dunes was characterized before and after Hurricane Ivan using Empirical Orthogonal Function (EOF) analysis and related through Canonical Correlation Analysis (CCA). The height and extent of the foredune, and the presence and relative location of the backbarrier dunes, varied alongshore at discrete length scales (of ~ 750, 1450 and 4550 m) that are statistically significant at the 95% confidence level. Cospectral analysis suggests that the variation in dune morphology is correlated with transverse ridges on the inner-shelf, the backbarrier cuspate headlands, and the historical and storm-related trends in shoreline change. Sections of the coast with little to no dune development before Hurricane Ivan were observed in the narrowest portions of the island (between headlands), west of the transverse ridges. Overwash penetration tended to be larger in these areas and island breaching was common, leaving the surface close to the watertable and covered by a lag of shell and gravel. In contrast, large foredunes and the backbarrier dunes were observed at the widest sections of the island (the cuspate headlands) and at crest of the transverse ridges. Due to the large dunes and the presence of the backbarrier dunes, these areas experienced less overwash penetration and most of the sediment from the beachface and dunes was deposited within the upper-shoreface. It is argued that this sediment is returned to the beachface through nearshore bar migration following the storm and that the areas with larger foredunes and backbarrier dunes have smaller rates of historical shoreline erosion compared to areas with smaller dunes and greater transfer of sediment to the washover terrace. Since the recovery of the dunes will vary depending on the availability of sediment from the washover and beachface, it is further argued that the alongshore pattern of dune morphology and the response of the island to the next extreme storm is forced by the transverse ridges and island width through alongshore variations in storm surge and overwash gradients respectively. These findings may be particularly important for coastal managers involved in the repair and rebuilding of coastal infrastructure that was damaged or destroyed during Hurricane Ivan.

Explore related subjects

Geomorphology Article

Source-reported bounding extent: 30.313616689930676° to 30.40012204559436° latitude; -87.30148315429688° to -86.52008056640624° longitude. This indicates report coverage, not an exact sampling location. View area on OpenStreetMap.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

C. Houser, C. Hapke, S. Hamilton. 2008. Controls on coastal dune morphology, shoreline erosion and barrier island response to extreme storms. https://doi.org/10.1016/j.geomorph.2007.12.007

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related USGS reports

USGS2026

The influence of riparian zone grazing on channel stability in an arroyo

The introduction of large herds of domesticated grazing animals by European immigrants in the late 19th century is one primary hypothesis used to explain the initiation of arroyo cutting in the American West. But studies designed to quantify the effects of grazing on watershed hydrology and sedimentation have had conflicting results that are often scale dependent. We used a before-and-after study design to examine effects of changes in cattle grazing practices on channel stability in Muddy Creek, an arroyo in the Colorado River headwaters. We digitized 620 meander loop cutoff geometries in the alluvial bottom of Muddy Creek and used meander loop cutoff rate as a broad measure of channel stability. Poisson regression modeling indicated that the change in grazing practices caused an order-of-magnitude decrease in meander loop cutoff rate that was independent of other forcings. Repeat measurements of channel geometry showed a decline in bankfull channel width of about 40% after the changes were implemented. Increases in riparian vegetation density are deduced to be the primary mechanism for the increase in channel stability. Prior to the changes in grazing practices, at least one meander loop cutoff occurred each year, some of which were large enough to create headcuts that scale with the depth of downcutting in this arroyo system. Our analysis demonstrates the profound effects that different grazing practices have on channel stability in headwater arroyo systems, and the potential for grazing animals to initiate a cascade of sediment yields to receiving stream networks.

Colorado, Utah, Wyoming↗

USGS2026

Revisiting the geochronology of late Quaternary marine terraces and uplift rates in coastal Santa Barbara County, California, USA

In several early studies, central California marine terraces between Santa Barbara and Point Conception were interpreted to record sea-level high stands of the last interglacial complex, ∼80 ka to ∼120 ka (marine isotope stage [MIS] 5). These ages and their elevations (∼20 m to ∼45 m) indicate modest rates of tectonic uplift, similar to those from other localities in southern and central California. A recent study, using a combination of luminescence and radiocarbon dating, has challenged the older age interpretations, implying much younger terrace ages, between ∼40 ka and ∼55 ka (MIS 3). From these new ages and a considerably lower sea level during MIS 3, much higher rates of tectonic uplift are inferred. In the present study, new uranium-series ages of terrace corals and amino acid age estimates of terrace mollusks were determined to test these competing interpretations. With the exception of a low-elevation terrace in Isla Vista (near Santa Barbara) that dates to MIS 3, terraces farther west are interpreted to date to MIS 5 and imply tectonic uplift rates of 0.20–0.34 m/kyr. A compilation of data for the region yields a decreasing rate of late Quaternary uplift from east, near Ventura, to west, near Point Conception. This trend is interpreted to reflect a decreasing influence of the processes of compression and crustal shortening south of the Big Bend in the San Andreas fault.

California↗

USGS2025

Toward an efficient framework for remote sensing of river bathymetry: Comparing sensors and algorithms on an inaccessible proglacial river in Alaska

Remote sensing can provide reliable information on river depths and this approach might be particularly valuable in areas that are difficult to survey via conventional field methods. In this study, we assessed the potential to map the bathymetry of an inaccessible proglacial river in Alaska from both aerial orthophotos and a multispectral satellite image. In addition, we evaluated a variety of depth retrieval algorithms with different input data requirements, including some methods that require field measurements of water depth for calibration and other techniques that can be applied even when such field data are not available. These approaches might enable more efficient use of remote sensing methods by resource management agencies. Our results suggest that bathymetric mapping along the turquoise-colored river we examined was not only feasible but highly accurate ( R 2 up to 0.94) for both types of image data. Algorithms that use paired observations of depth and reflectance to train depth retrieval models were the most accurate, with errors on the order of 15%–20% and little or no bias. Alternative techniques based on hydraulic and statistical concepts also led to strong agreement between predicted and observed depths but were more susceptible to systematic biases toward under- or over-estimation of depth. In contrast to clear-flowing streams, bathymetric mapping in this environment was enabled by a direct relationship between the depth and brightness of the water due to scattering by suspended sediment. In selecting an appropriate depth retrieval method, a compromise might need to be reached between the level of field effort invested and the accuracy of the resulting image-derived bathymetry. Standalone software for implementing these techniques is freely available.

Alaska↗