Real-time observations and predictions of scour burial at the Martha’s Vineyard Coastal Observatory

Abstract

Mine burial by scour was measured in real-time using cylindrical instrumented mines and rotary and two-axis pencil beam sonar. Two mines and the sonar were connected to a shore-based facility at the Martha’s Vineyard Coastal Observatory. Data on mine movement (heading, pitch, and roll), scour pit geometry, percent burial, and environmental processes responsible for scour burial including significant wave height, period, and tidal height were analyzed daily and presented on a mine burial web site. Sonar images show scour pits developing around the mines in response to storm generated significant wave heights greater than 2.0 m. Mines pitch, change heading as they roll into scour pits. A comparison of the observed mine burial and real-time predictions using a modified version of the Whitehouse equations for wave-induced scour model exhibited good agreement suggesting mine burial by scour in similar sandy environments is predictable from bathymetry, sediment type, and measured or predicted surface wave conditions. The Coastal Observatory at Martha’s Vineyard provided a unique opportunity for real-time data collection and analysis of both sediment transport events and seafloor-object interactions during storms. [Work supported by ONR.]