Detecting Bedform Migration from High Resolution Multibeam Bathymetry in Portsmouth Harbor, New Hampshire, USA

TitleDetecting Bedform Migration from High Resolution Multibeam Bathymetry in Portsmouth Harbor, New Hampshire, USA
Publication TypeThesis
Year2009
AuthorsFelzenberg, J
Degree and ProgramMaster of Science
DegreeEarth Sciences/Ocean Mapping
Number of Pages107
Date Published09/2009
UniversityUniversity of New Hampshire
LocationDurham, NH
Keywordsbedform migration, portsmouth harbor

A study was undertaken to quantify dune migration in Portsmouth Harbor, New Hampshire, USA from repeat high-resolution multibeam echosounder (MBES) surveys. Repeat MBES surveys were conducted in June 2007 and July 2008 over periods ranging from 6 hours to 7 days in order to capture the response of dune morphology to ebb-flood and spring-neap tidal cycles. A new technique was developed for detecting bedform migration. This approach utilizes a fingerprint-detection algorithm (Bishnu et al., 2002) to convert the bathymetric surface to a binary map of bedform crests, which are subsequently tracked using a spatial cross-correlation technique (Duffy and Hughes-Clarke, 2005). Acoustic current-meter observations from July 2008 provided context for the observed bedform-migration patterns, and were subsequently used to compute bed shear stress. Results indicate that dune migration occurred over periods as short as 6 hours. Dune migration distances in excess of 2 m were observed over 6- and 7-day periods.