The Charleston District’s survey section is no stranger to using advanced visualization technologies to support the District’s decision makers. Recently, while hosting a seafloor mapping S.T.E.M. outreach event with the College of Charleston’s Marine Geology Mapping Group, the survey team was introduced to the Dynascan mobile Light Detection and Ranging (LiDAR) mapping system.
The District’s surveyors saw significant benefits to using this technology to the support their mission. Following the event, the team collaborated with the equipment vendor to perform a test and evaluation of the mapping system. The team mounted the LiDAR system on its 23 foot survey vessel and quickly configured the systems for operation.
After a few uses, it became evident that this would be an excellent tool to aid in improving maintenance and management of District projects. Due to improved operations and cost savings from the equipment, a LiDAR system was acquired in 2013.
The need for accurate, time-sensitive topographic data arose soon after at the Morris Island disposal site in Charleston Harbor. The large and remote site posed access difficulties that would be costly to overcome using conventional methods. A traditional GPS survey of the project area would have taken several days to complete. To surmount these challenges, the survey crew designed and fabricated a frame to mount the LiDAR on an all-terrain vehicle.
With the ATV, the team was able to complete the survey in one day, collecting significantly more data points than could have been collected otherwise.
The ability to move the unit from a vehicle to a vessel, with full functionality achieved in less than an hour, was an obvious benefit. That was the official birth of the rapid assessment mobile LiDAR, or RAMbLr.
Anyone who has worked with LiDAR can attest that its benefits cut both ways. More data can be a positive (in terms of detail provided) or a negative (when managing massive datasets). The survey crew and design engineers collaborated to develop procedures that ensure a balanced data acquisition strategy of prioritizing the collection of high-value data necessary for project design while reducing processing time.
With the integration of the RAMbLr, the team has capitalized on its newest ability by providing an efficient long-term beach monitoring solution. The South Carolina coast is characterized by wide beaches. Of these beaches, the Corps has periodic storm damage reduction projects in Myrtle Beach and Folly Beach. Using this system to collect snapshots in time of beach conditions allows scientists and engineers to understand the complicated dynamics of the sea and shore interface.
Many of the natural processes on these beaches are complicated by the use of shoreline stabilization structures and the data obtained with this technology will enable improved understanding and assessment of the structures’ performance. In addition to long-term monitoring, the system can be deployed quickly before and after a major storm to estimate material lost from protective beaches. This could help in long-term planning in an era of predicted increased storms.
The system was employed during the Folly Beach shore protection project to provide condition assessments in addition to traditional quality assurance checks. The data collected with the system has been invaluable to project managers in assessing the current state of the project. The graphics generated from this data provide easy-to-read topographic maps that can be used together with local sponsor reports to document and explain before and after conditions of storm impacts on the beach projects.
Press Release, July 15, 2014