Rapid remote determination of hydrographic data for modified surf Index calculations and naval applications

Abstract

Amphibious operations present a unique set of challenges to naval personnel. Among these challenges is the need to rapidly obtain reliable real-time data for the surf zone, a high-energy environment in which beach profiles and wave regimes may not be known a priori, are difficult to measure remotely, and can change rapidly over time or following extreme weather events. The Naval Beach Group (NBG) has a requirement for hydrographic and beach surveys to plan amphibious landings, while Underwater Construction Teams (UCTs) have a mission to provide hydrographic survey data for the naval component of Joint Logistics Over-The-Shore (JLOTS), in addition to underwater construction, surveys, and repairs. The NBG and UCTs currently conduct surveys and inspections using divers, shore-based personnel, sonar (single, multi-beam, and side-scan), and remotely operated vehicles (ROVs).

The Modified Surf Index (MSI) is a non-dimensional number calculated from eight wave, wind, and current characteristics within the surf zone and is determined by Naval Beach Master Unit (BMU) personnel. The calculated MSI value is used as a go/no-go mission criterion for various landing craft during training, operational, or wartime missions. Unfortunately, some measured MSI parameters are subjective, dependent on operator experience and require operator presence on the beach. In addition, their determination is time intensive. U.S military forces desire a single technology or suite of measurement techniques that are capable of rapidly collecting accurate real-time data within the surf zone to aid in amphibious landings, surveillance, recovery, reconnaissance, cable replacement and repair, underwater construction, and ordinance detection.

The purpose of this thesis is to investigate the existing technologies available for bathymetric mapping and MSI calculation; to include data collection accuracy, post-processing time, range, deployability, and potential for military applications. Technologies explored will include remote and autonomous underwater vehicles, radar, LIDAR, sonar, unmanned aerial vehicles, optical imagery, GPS equipped jet-skis outfitted with precision echo sounders, classic surveying techniques, inference from offshore wave field data, and surf zone modeling. Understanding the current capabilities and limitations of existing technologies will enhance Naval readiness and increase the timeliness and accuracy of obtaining hydrographic data in the surf zone for current and future Navy operations.