Effects of using inclined parametric echosounding on sub-bottom acoustic imaging and advances in buried object detection

This study reports an adaptation of a parametric echosounder system using 15 kHz as secondary frequency to investigate the angular response of sub-bottom backscatter strength of layered mud, providing a new method for enhanced acoustic detection of buried targets. Adaptions to achieve both vertical (0°) and non-vertical inclination (1– 15°, 30°, 45° and 60°) comprise mechanical tilting of the acoustic transducer and electronic beam steering. Data were acquired at 18 m water depth at a study site characterized by a flat, muddy seafloor where a 0.1 m diameter power cable lies 1–2 m below the seafloor. Surveying the cable with vertical incidence revealed that the buried cable can hardly be discriminated against the backscatter strength of the layered mud. However, the backscatter strength of layered mud decreases strongly at >3±0.5° incidence and the layered mud echo pattern vanishes beyond 5°. As a consequence, the backscatter pattern of the buried cable is very pronounced in acoustic images gathered at 15°, 30°, 45° and 60° incidence. The size of the cable echo pattern increases linearly with incidence. These effects are attributed to reflection loss from layered mud at larger incidence and to the scattering of the 0.1 m diameter buried cable. Data analyses support the visual impression of superior detection of the cable with an up to 2.6-fold increase of the signal-to-noise ratio at 40° incidence compared to the vertical incidence case

Investigation and Recovery of USS Westfield (Site 41GV151) Galveston Bay, Galveston County, Texas

This report represents the culmination of fourteen years of marine archeological investigations by PBS&J (now Atkins North America, Inc.) associated with the Texas City Channel Improvement Project. Over that time span Atkins’ investigations of the site of USS Westfield (41GV151) have included numerous remote-sensing surveys using various combinations of marine magnetometer, side-scan sonar, sector-scan sonar, sub-bottom profiler, and ROV; three diving investigations totaling 64 dives and over 72 hours of bottom time; and archeological salvage of Westfield resulting in the recovery of at least 8,380 artifacts. These combined efforts were undertaken in order to satisfy the responsibilities of the U.S. Army Corps of Engineers under Section 106 of the National Historic Preservation Act (Public Law 89-665; 16 U.S.C. 470) and the Antiquities Code of Texas (Texas Natural Resource Code, Title 9, Chapter 191). The archeological investigations reported in this document were conducted under Texas Antiquities Permits 3878, 4622, and 5271, issued by the Texas Historical Commission, and Federal Permits for Intrusive Archaeological Research on U.S. Naval Cultural Resources, Nos. PBSJ-2009-001 and PBSJ2009-0002, issued by the U.S. Naval History and Heritage Command. The minimum reporting and survey requirements for marine archeological studies conducted under a Texas Antiquities Permit are mandated by The Texas Administrative Code, Title 13, Part 2, Chapters 26 and 28, respectively. The results of six separate site investigations are reported in this document, including Contract DACW64-03-D-0001Delivery Orders 0004 and 0005, conducted in 2005 and 2006, respectively, and additional site assessments and data recovery conducted under Delivery Order 0006 and four subsequent delivery order modifications in 2007, 2009, and 2010. The results of Delivery Order 0004 conclusively demonstrated that the source of recorded anomaly GV0031 was a shipwreck (and given the site designation 41GV151), which tentatively matched the time period and characteristics of Westfield. The results of Delivery Order 0005 further substantiated the identity of 41GV151 as USS Westfield and concluded that the site demonstrates several criteria for eligibility to the National Register of Historic Places. Delivery Order 0006 resulted in the data recovery operations, which are the primary focus of this report

Oceanus.

v. 26, no. 3 (1983

PB2Y Coronado Flying Boat Archaeology and Site Formation Studies, Tanapag Lagoon, Saipan

The focus of this thesis is the further study of both pre- and post-depositional site formation processes that affect submerged WWII aircraft, specifically an unidentified US Navy Consolidated PB2Y Coronado flying boat in Tanapag Lagoon, Saipan, Commonwealth of the Northern Mariana Islands. The study of submerged aircraft is a relatively recent field of study in maritime archaeology. With the inclusion of aircraft in the Sunken Military Craft Act of 2004, these studies have become increasingly more important to stakeholders such as the US Navy.    Site formation process studies stipulate that a crucial aspect of the accurate interpretation of a site first requires a thorough understanding of the processes that create and subsequently alter the site. For terrestrial archaeologists, as well as those maritime archaeologists studying shipwreck sites, a database of this knowledge exists. For submerged aircraft, however, this database is incomplete. This thesis will contribute to the overall understanding and interpretation of submerged aircraft sites through the studies of the processes that created and subsequently affected the Tanapag Lagoon PB2Y Coronado site. Archaeological and historical evidence will be examined to identify the specific aircraft, determine its cause of crash, and understand any cultural or natural factors that may have affected the site. This will contribute further information about site formation processes on three different levels: specific (Consolidated PB2Y Coronado), general (flying boats), and broad (wreck type and artifact distribution).   Further, this information will be used to identify management challenges specific to this site, and offer solutions to those challenges. The management issues and solutions, as well as a completed application for the National Register of Historic Places, will be turned over to the relevant stakeholders. This will assist in the proper protection and management of not only this specific site, but will also be applicable to other submerged aircraft sites throughout the Pacific in particular and the world in general.  M.A

The future environment: US and world trends

The impact of rapidly developing technology and industrialization on human society and environments is considered