Bald earth digital terrain modeling with UAS collected LiDAR
Fort Laramie National Historic Site in Wyoming
In 2017, the National Park Service approached U.S. Geological Survey’s National Unmanned Aircraft Systems Project office to acquire geospatial data in support of developing a flood management plan for the Fort Laramie National Historic Site, Fort Laramie, WY. Originally established as a private fur trading fort in 1834, Fort Laramie evolved into the largest military post on the northern plains and eventually became part of the National Park System in 1938. Located at the confluence of the Laramie and North Platte Rivers, the park experienced two consecutive 100-year flood events in 2015, and 2016. Increased damage to the park highlighted a need to implement a flood management plan.
The mission objective was to collect a high-density LiDAR point cloud data to generate a bald earth digital terrain model to be used in additional flood analysis for the park. A quality control check was implemented with a stand-alone survey for research accuracy comparisons.
The two remote pilots collected 24 GB of RAW LiDAR scans and 53 GB of raw imagery over a 3-day period. The average point density of the cloud product was approximately 210 points per square meter. The integrated Yellowscan Surveyor LiDAR payload penetrated areas of thick vegetation to provide ground based returns near the river channel. River channels are especially prone to high vegetation growth and the ability to accurately scan and attribute the LiDAR point cloud, without null data, is necessary to create a bald earth digital terrain model of the surrounding channel. The Yellowscan Surveyor allowed the data collection to be conducted with a two-man crew, which allowed the field crew to focus on flying safely. Aviation Safety is the upmost importance to all DOI’s UAS research activities.
"The LiDAR data collected will be combined with channel cross sections of the Laramie River to create a floodplain map for evaluating the vulnerability of park assets affected by more frequent flooding events. This will better inform NPS management decisions for mitigating flood risks at Fort Laramie National Historic Site." - NPS Natural Resource Manager.
Study Point of ContactNell Conti
Intermountain Region GIS Coordinator
National Park Service