The growing reliance on precise topographic data requires a coordinated effort. This need is well-known by the U.S. Geological Survey (USGS), which highlighted the value of improving 3D elevation data in its National Enhanced Elevation Assessment (NEEA) in 2011 and continues to support the data’s expanding and evolving applications with its 3D Elevation Program (3DEP).
“The NEEA study provided a cost-benefits analysis on the value of topographic LiDAR data for the U.S.,” said Mike Meiser, geospatial program director for Woolpert a global architecture, engineering and geospatial (AEG) firm. “The study found that roughly 70 percent of the National Elevation Dataset was more than 30 years old and that data was not sufficiently accurate to meet user requirements for multiple applications.”
Following the NEEA study, and the development of the 3DEP program, USGS Geospatial State Liaisons have worked with various federal, state and local agencies to plan and prioritize data collections and make the data available to the public. The USGS, in support of the 3DEP initiative, is systematically collecting 3D elevation data over an approximately eight-year period of the conterminous U.S., Alaska, Hawaii and U.S. territories.
“The primary goal of 3DEP is to collect Quality Level 2 (QL2) LiDAR data—QL2 is collected at 2 points per square meter or better—across the continental U.S., so organizations can have access to high-density elevation data for many important planning and mitigation missions,” Meiser said. “Nationwide coverage via QL2 LiDAR data has been estimated to provide a 5:1 return on investment across many disciplines, and that data will provide a base map of high-accuracy elevation data essential to monitoring the changing landscape.”
QL2 LiDAR data is a highly accurate tool ideal for coastal zone management, conservation planning, wetlands mapping, soil mapping and coastal resiliency. Quality Level 1 (QL1) LiDAR data, collected at 8 points per square meter, produces a higher-density point cloud. It can be used to model more refined features—from very small hydrologic features to the degree of sag in a power line, for instance—and can penetrate heavily forested areas to fully characterize a dense vegetation structure.
“Prior to the 3DEP program, most LiDAR data acquisition was less dense than QL2, was acquired with a less coordinated approach and had varying specifications,” Meiser said. “Having the USGS Base Specification for LiDAR has provided standardized guidelines for LiDAR projects and has greatly increased the overall quality and compatibility of LiDAR between users. Prior to the improved coordination we see today, specifications ranged widely from project to project.”
3DEP’s systematic, coordinated approach avoids data duplication and mandates uniform specifications, increasing efficiency and cutting costs. It organizes LiDAR collections to ensure regions are mapped once and that data is shared so it can be used repeatedly.
“The USGS created an efficient, consistent program and became the national agency responsible for managing a National Elevation Dataset and working with NOAA, FEMA, the NRCS (National Resources Conservation Service), state and local governments, along with private industries,” Meiser said. “With 3DEP, we’re all working together in this very successful public-private partnership to map the U.S. with high-accuracy, high-density LiDAR. And I’m happy to report that about 60 percent of the work is now completed.”
There are several compelling use cases for enhanced LiDAR elevation data, including:
#1 Floodplain mapping
In the U.S. alone, shifting topography adversely affects life and livelihood from Florida to Alaska, as intensified storm activity and dissipating sea ice have caused persistent coastal flooding, coastal erosion and habitat loss. Highly accurate LiDAR and imagery data provide immediate, accurate assessments of affected regions to support coastal mapping, and to plan for resilience, response and recovery.
#2 Mineral extraction
Mining companies are using LiDAR as a more efficient means to locate, evaluate, and extract critical minerals used in electronics, agriculture, manufacturing and construction products across the globe. “The Stillwater Complex project (https://pubs.usgs.gov/pp/1038/report.pdf) is a great example of this,” said Meiser. “The U.S. depends on foreign countries for many of its critical minerals. The goal is to find and extract some of these minerals locally. LiDAR elevation data can provide a foundation for analyzing rich data, so companies can decide where to explore without the need to conduct extensive field excursions for exploration.”
#3 Forest management
LiDAR data collected before a wildfire can be used to predict and address a fire’s behavior, path, and intensity, while LiDAR data collected after a wildfire can be used to analyze hazards created by the fire. “LiDAR data provides 3D information about the forest canopy and vegetation structure, which is used to support wildfire fuel management,” Meiser said. “Having accurate, high-resolution imagery regarding topographic conditions like elevation, slope and aspect provides information for analyses that help protect communities, livelihoods, and infrastructure, and supports reconstruction efforts and ecological assessments.”
3DEP LiDAR projects all have a basis in helping the public in some way, which Meiser said makes the work very rewarding.
“With projects like collecting LiDAR data following the recent California wildfires, a process that helps predictive models of flood and mudflow hazards, you have a real sense of how the data is going to help people,” said Meiser. “Or work we’ve performed in the Yukon Delta in Alaska, where LiDAR data has helped mitigate inundation problems that are wiping out entire villages. When you have a clear vision of how the information you’ve gathered is going toward the greater good of public safety, it makes the work extremely gratifying and empowering. It’s just the best.”