The 3D Elevation Data Program is a Game-Changer

For decades, engineers have relied on a patchwork of data consisting of field surveys, orthographic photos, and other sources to piece together baseline topographic data for infrastructure design and other purposes. The United States Geological Survey (USGS) has long been aware that 3D elevation data for the entire United States would bring significant economic and practical value to local, state, and federal initiatives; now in 2026, after roughly eight years of targeted data collection through state and local partnerships, a dataset once considered a “pipe dream” has become a reality.

The USGS 3D Elevation Program (3DEP), consisting of high-resolution light detection and ranging (or LiDAR) data for the conterminous U.S., its territories, Hawaii and Alaska (with Interferometric synthetic aperture radar), brings consistent topographic elevation data to the aid of modern-day planning and crisis management. USGS calls 3DEP a “digital twin of the nation’s topography,” and this is a fair assessment. Decision-making in complex hydrology, hazard mitigation, and other related fields gains in accuracy as 3DEP replicates with high-quality data countless surface details. More detail reduces uncertainty and allows engineers to sharpen and refine the engineering analysis, ultimately improving the quality of engineering projects across the board.

Advantages and applications

Lidar data are used increasingly in fields as diverse as conservation, urban planning, precision agriculture, and hazard mitigation. Lidar works by way of tracking sensor-emitted light pulses that reach Earth’s surface and return, generating millions of elevation points in what is referred to as a “point cloud”. These points represent terrain in all its variability: tree canopy, buildings, bare land, and other surface features. Digital elevation models (DEMs) can be derived from lidar data and represent “bare-earth”, stripped of surface features in a data-dense topographic profile. Ultimately, 3DEP reduces the inconsistency that creeps into engineering analysis via outdated maps and other error-prone sources of data. Regular cycles of additional data collection will ensure that the 3DEP dataset remains current and continues to detect fine-scale changes in the natural and built landscape.

Lidar is already used in a broad range of water management fields, from floodplain mapping, hydrologic model development, dam breach analysis, and watershed delineation, to many others. All fields benefit from a consistent baseline from which to compare different structural designs or stormwater management strategies. Moreover, these data may be easily integrated with other data relating to hydrography, vegetative cover, and others for additional levels of analysis. For example, in one recent study by Oladunjoye et al., lidar was used in combination with multispectral sensing to track and assess the long-term performance of stormwater management practices over time.

3D elevation data in practice

From a hydrologist’s perspective, one of the principal advantages of 3DEP is the ability to do preliminary terrain processing without the need to send out a field crew for early-stage survey work. In a hypothetical case of reconstructing a circa1950s dam, for example, 3DEP DEMs could be used to delineate watershed geometry and upstream subbasins, identify flow paths, slope, basic surface contours, and more for purposes of building a preliminary terrain model. Similarly, 2D flood surfaces downstream of the structure may be plotted for downstream flow in the event of dam breach. Important details showing subtle terrain variability —often indiscernible in coarser elevation data—can be identified before design flaws affect model accuracy.

USGS is still in the process of integrating 3D hydrography data, but supplementary data for channel bathymetry, storage curves, dead storage, and other hydrologic details would be necessary as well. It’s important to keep in mind that as good as lidar is, areas of dense vegetation, rocky outcroppings, or where earthworks have recently been modified can hide important details. In these cases, field surveys to identify fine-scale detail are necessary. Complex projects like dam reconstruction also typically require supplementary topographic surveys, field-validated measurements, geotechnical information, and other structure-specific data. Despite these limitations, 3DEP data provide an invaluable baseline of information for further analysis and investigation.

The 3DEP dataset is only one subpart of the comprehensive 3D National Topography Model vision launched by USGS. When the project is complete, this “digital twin” of the U.S. will consist not just of 3D elevation data, but important hydrographic data (3DHP) as well. Our profession will be laboring under engineering challenges for years to come, but the quality and scale of the data that are coming online lately are keeping pace with need. Our charge is to continue to develop ways to make the best use of them.