Morphological Behavior - Coastal System Change at Fire Island, New York

Science Center Objects

Sand is constantly exchanged between beaches, dunes, and the submerged shoreface, which includes the nearshore sand bar system. We use specialized vessels and equipment to understand the feedbacks between nearshore morphology changes and coastal change to improve predictions of future impacts.

Repeat mapping of nearshore morphology off of Fire Island since Hurricane Sandy is providing detailed information about the evolution of the submerged shoreface during the period of recovery after Sandy, and in response to seasonal changes in waves and currents. Because of shallow water depths and breaking waves, bathymetry data are collected using single-beam echosounders mounted on personal watercraft. Documenting elevated or unexpected variability in sand bar morphology along the island provides important information for coastal change models that predict what the coast will look like in 6 months to hundreds of years.

Photo collage of researchers on personal watercraft at Fire Island

Personal watercraft were utilized to collect bathymetry in the surf zone and shore face (top left), setup on the beach (top right), instrument configuration (bottom left) and Pelican case hardware configuration (bottom right). Credit: USGS

Island wide average cross shore profiles

Island wide average cross shore profiles showing the response and recovery from pre-Hurricane Sandy October 2012 to post-Hurricane Sandy: December 2012, October 2013, and Jun 2014. Credit: Tim Nelson, USGS

Comparing maps of the shoreface from multiple surveys allows us to quantify changes that resulted from Sandy and document subsequent changes in the years since the storm. The data show changes in the steepness of the nearshore profile and shifts in the shape and location of the shore-parallel sand bar.  Mapping shifts in sand volume between the beach and the sand bar helps us to understand where sand is in the coastal system over short time scales, providing key information about storm-reponse and recovery processes.