The objective of this project is to demonstrate the use of a physics-based acoustic inversion technique to provide a wide-area survey of geoacoustic parameters and their associated uncertainties needed for unexploded munitions detection and classification. This will be accomplished by working with colleagues at Teledyne-RESON to collect a second set of multibeam echosounder data in Sequim Bay in late summer of 2021. This new dataset will be representative of a typical survey for which a commercial implementation of the inversion will be used and will not involve any additional environmental characterization. This will allow the project team to identify and address any issues that arise in processing such a large and continuous dataset and to develop and refine the data output such that it can be processed by commercial survey software to visualize the geoacoustic parameters and their uncertainties.

Using historical sonar and sediment sampling data, a large survey area will be identified which encompasses a majority of the sites sampled in the 2019 field test. Working with Teledyne-RESON, the T-50 multibeam sonar used in 2019 will be deployed over the side of the R/V Robertson and used to collect densely sampled, survey-quality datasets. Data collection will take place over three days and surveys will be conducted at multiple frequencies from 200-400 kHz. These datasets will be processed using the physics-based inversion algorithm to produce wide-area maps of multiple sediment parameters and their uncertainties.

A physics-based, high-frequency acoustic inversion does not require ground-truth data, thus reducing efforts and costs in wide-area surveys for sediment characterization. The data collected under this effort should help complete refinement of the inversion code and be in a position to address the requirements that must be met to integrate the algorithm into a commercial application. Also, in developing approaches to meaningfully visualize the inversion output, the project team hopes to demonstrate to both SERDP and the user community the capabilities of the inversion and establish a clear path to transition under ESTCP.

Additional work to be conducted under MR18-1406.