Evaluating nearshore mapping capabilities of an autonomous kayak

Abstract

Deep drafted survey vessels, autonomous underwater vehicles, and expensive aerial LiDAR surveys have limitations when conducting bathymetric surveys in the nearshore, shallow, turbid conditions. These limitations are overcome with lightweight, shallow drafted autonomous surface vehicles (ASVs). Here, an autonomous kayak is tested as a practical, nearshore bathymetric survey platform, particularly in response to storm events. The accuracy and functionality of the autopilot aboard the kayak was evaluated, and the preliminary results show the on-track variability to be within 10% of the error of the autopilot's GPS. The autonomy of the system allows for repeatable and comparable data sets over the same area. A storm in January 2017 allowed for a storm response survey in which the kayak was deployed three days before and six days after a storm event occurred at Broadkill Beach, Sussex County, DE. These surveys further proved the viability of such a platform for not only nearshore coastal surveys but storm response bathymetric surveys as well. The quality of bathymetric and side-scan data recorded by two different single beam echo sounder/side-scan units have also been compared and evaluated, allowing for a cost-benefit analysis of the platform's payload. The preliminary budget for the kayak platform, including a single beam echo sounder/side-scan unit is relatively inexpensive at $3000. Based upon the early results of accuracy, cost, and modularity of this system, it is a viable platform for nearshore bathymetric surveying.