Surf Zone (SZ) Mapping and Sensor System

The importance of Very Shallow Water (VSW) and the Surf Zone (SZ), VSW/SZ, for littoral operations is well known. Both ocean dynamic conditions and bathymetry may vary significantly in space and time. The harsh SZ environment (mainly due to currents, waves, and surf) makes data collection using in-situ sensors or Autonomous Underwater Vehicles (AUVs) difficult especially for a mobile sensor system to be used where needed. An innovative bottom drifting sensor system is proposed to measure oceanographic variables, including bathymetry, in 3-D space and time in the SZ and extending into the VSW region. A drifter would be relatively invulnerable to breaking waves and would utilize near bottom currents to provide drifter locomotion without using its own power. While bottom drifters would be miniaturized, they could be large enough to accommodate several sensors to measure bathymetry, waves, surf, and other data. Several deployed drifters would constitute a mobile SZ measurement and mapping system. Techniques will be investigated and developed to track drifters recognizing SZ acoustic limitations. Because of SZ currents (e.g. undertow and rip currents), drifters will generally be transported outside of the SZ where, particularly for scientific experiments, they could return to the surface for reuse.