2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 39-10
Presentation Time: 9:00 AM-5:30 PM

OBSERVATIONS OF RIPPLE VARIABILITY ALONG THE ASSATEAGUE ISLAND INNER CONTINENTAL SHELF


FRIEDRICHS, Andrew, Middlebury, VT 05753, DUVAL, Carter, College of Earth Ocean and Environment, Newark, DE 19716 and TREMBANIS, Arthur, College of Earth Ocean and Environment, University of Delaware, 109 Penny Hall, Newark, DE 19716, amfriedrichs@middlebury.edu

Fundamental characterization of spatial and temporal patterns in ripple bedform evolution remains incomplete. This study works to address this issue by examining the effectiveness of different sonar systems to characterize fine-scale changes in ripple morphology, through the use of an automated bedform analysis technique. Additionally, insight concerning seabed morphological variability over the span of months is given, with the goal of outlining more focused questions for future work. In May and July of 2015, high-resolution boat and AUV-mounted side scan sonar systems were used to map a series of ripple patches offshore of Assateague Island National Seashore. Through this experience, a commentary was developed on the efficiency of each sonar system for gathering detailed data on large-scale seasonal ripple morphology, as well as the effectiveness of the Fingerprint Algorithm automated bedform analysis technique in analyzing such complicated bedforms. In creating a before and after study of how spring and summer wave conditions affected changes in the local seabed, parallels were drawn between the more storm-intensive months of April and early May and the existence of clearly sorted bedforms, as well as how the comparatively calm late May through mid-July resulted in changes to and the disappearance of these ripple patches. A connection between wave data and ripple orientation was then found both through buoy data analysis and predictive modeling. Finally, speculations are made on the effects that varying sediment size had upon the ripple morphology that was examined.