Date of Award

8-30-2022

Document Type

Campus Access Thesis

Degree Name

Master of Science (MS)

Department

Marine Sciences and Technology

First Advisor

Mark Borrelli

Second Advisor

Eugene Gallagher

Third Advisor

Crystal Schaaf

Abstract

Coastal waters are crucial to the socio-economic activities of humans, as well as to the health of our global oceans. Unfortunately, they have also long been a dumping ground with an ‘out of sight, out of mind’ mentality. Remote object differentiation in shallow water coastal environments is becoming increasingly important in the maintenance and restoration of these critical habitats. Detection, characterization, and localization (DCL) techniques are being developed around the use of the EdgeTech 6205 Phase-Measuring Sidescan Sonar (PMSS) in the coastal waters around Cape Cod, MA, USA. This instrument offers a unique look into the seafloor because of its ability to simultaneously collect co-located sidescan backscatter and bathymetry in extreme shallow water environments (<1m water depth). Inherent with the bathymetry is an uncalibrated amplitude backscatter dataset, referred to in this study as reflectivity backscatter. This reflectivity backscatter has been minimally used in current literature due to the coincidence of the sidescan backscatter dataset. This work aims to use the reflectivity backscatter to detect and differentiate between various objects on the seafloor, including unexploded ordnance (UXO), and placed marine debris such as derelict lobster pots, boat propellers, and car tires. The differentiation from multiple seabed types including sand, mud, and cobble, and different types of objects occurred through various statistical analysis methods including binomial and multinomial logistic regression (BLR, MLR). These methods have been applied to create statistical regression models for several variables including reflectivity backscatter amplitude, sounding distance from nadir, per-ping vessel roll, the orientation offset between per-ping vessel heading and object orientation, and all combinations of these variables. These statistical tests produced maximum likelihood odds ratios of individual soundings being associated with the various seabed and object types. Results from these analyses shows that DCL could be possible with reflectivity backscatter from PMSS, but significantly more testing is needed.

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