28 Aug 2023

Improving Spatial and Temporal Monitoring of Dredging Operations Incorporating Unmanned Technologies

Abstract: The US Army Corps of Engineers (USACE) is responsible for maintaining safe and navigable waterways through the periodic dredging of shoaled sediment from federal navigation channels. While dredging, a portion of the bottom sediments become resuspended creating a sediment plume near the dredging operation. Suspension of sediments during dredging and dredged sediment disposal operations continues to be a primary concern of regulatory agencies charged with the protection of environmental resources. Consequently, almost all dredging projects incorporate some level of regulatory compliance monitoring dedicated to measuring sediment resuspension. For numerous reasons the conventional approach using manned surface vessels to perform compliance monitoring is frequently ineffective in both adaptively managing dredging projects and ensuring true environmental protection. Advancements in unmanned platforms and payload technologies offer new and potentially more robust alternatives to conventional platforms. In this study, the use of unmanned aerial system (UAS) and weather balloon mounted camera imagery was demonstrated, and the use of an unmanned surface vessel (USV) to monitor turbidity in navigation channels and near a dredging operation. The imagery from the UAS and weather balloon were compared to in-situ turbidity measurements in a turbid distributary channel and near a dredging operation, while the USV was used to learn more about in-situ turbidity associated with passing vessels in a navigation channel. The results of the demonstrations show the unmanned technology bundled with off-the-shelf payloads can help to produce evidence-based information through easily interpreted aerial imagery and in situ measurements which can help to inform and manage water quality in areas where sediment plumes are an environmental concern.