High-resolution elevation data underpin landscape modeling and planning, which matter a great deal to Rhode Island's economy. Program managers balancing accuracy against cost seek the best elevation data they can get for climate change, environmental management, transportation design, aviation safety, river ecosystems, wildlife habitat, shellfish aquaculture, and mapping forests, parks, soils, wetlands and impervious surfaces. All depend on lidar (light detection and ranging), which builds a detailed 3D model of the ground and what stands on it.
The 3D Elevation Program
The USGS 3D Elevation Program (3DEP), run with Federal, State, Tribal, U.S. territorial and local partners, aims for the first-ever national baseline of consistent, high-resolution elevation data from lidar (IfSAR in Alaska). Baseline data are quality level 2 or better, with 1-meter or better elevation models and point clouds meeting the Lidar Base Specification 1.2 or newer; the data go into The National Map, free and unrestricted (download).
| Quality level | Vertical error, RMSEz (cm) | Pulse spacing (m) | Pulse density (per m²) |
|---|---|---|---|
| QL0 (highest) | ≤ 5 | ≤ 0.35 | ≥ 8.0 |
| QL1 | ≤ 10 | ≤ 0.35 | ≥ 8.0 |
| QL2 | ≤ 10 | ≤ 0.71 | ≥ 2.0 |
3DEP baseline lidar in Rhode Island as of December 2024: complete. Explore in the Lidar Explorer. USGS
Rhode Island's lidar
| When | |
|---|---|
| Spring 2011 | statewide quality level 3 lidar, through the Northeast Lidar Project |
| 2014–2018 | the National Oceanic and Atmospheric Administration, the U.S. Army Corps of Engineers and the USGS collect QL2 lidar for all coastal areas |
| Spring 2022 | statewide quality level 1 lidar, after the state, the USGS and the U.S. Department of Agriculture's Natural Resources Conservation Service identified uses that needed it — 100% complete (QL0 costs extra) |
Beach flights were timed within 120 minutes of predicted mean low tide, to measure the exposed beach as far into the intertidal zone as possible.
What it's used for
The National Enhanced Elevation Assessment (Dewberry, 2012) ranked Rhode Island's top 10 business uses for 3D elevation data by their estimated annual benefits:
- Flood risk management
- Natural resources conservation
- Coastal zone management
- Sea-level rise and subsidence
- Agriculture and precision farming
- Infrastructure and construction management
- Forest resources management
- Aviation navigation and safety
- Geologic resource assessment and hazard mitigation
- Homeland security, law enforcement and disaster response
Floods. Lidar feeds more accurate, cheaper hydrologic and hydraulic models for flood studies, retention-dam design, dam-breach studies and stormwater engineering — identifying vulnerable properties, improving floodplain decisions, and showing the public 3D models of how big storms could flood their areas.
The coast. Even before Hurricane Sandy in 2012, coastal towns were studying how sea-level rise and storm surge threaten natural resources, roads, buildings and cultural sites. That work needs current topographic and bathymetric data to keep up with a shoreline expected to change more often as storms grow stronger, more frequent and longer.
Infrastructure. With lidar on hand, costly field surveys are needed less, saving money on planning. It helps with preliminary highway alignment and design, earthwork estimates, road condition checks and safety projects; with regulatory compliance and site selection; with hydraulic design of bridges and culverts for big storms; and, combined with geologic, engineering, environmental and cultural data, with faster, cheaper project reviews.
Towns and cities. Municipalities use lidar for comprehensive plans, zoning, parcel slope models for subdivision runoff, climate adaptation, viewshed studies for proposed cell towers, mapping building footprints and impervious surfaces, correcting orthophotos, planning flood evacuation routes, and analyzing terrain and tree crowns in parks to improve visits.
Why a national program
Economies of scale, predictable federal investment, consistent coverage across boundaries, simpler buying, and national benefits of $690 million a year — potentially $13 billion more (Dewberry, 2012). Federal, State, Tribal, territorial, local and private partners can join through an annual Data Collaboration Announcement, fund USGS-managed projects or run their own with cooperative funds, and contribute data that meet 3DEP standards.
Sources
Based on Dan Walters, "The 3D Elevation Program—Supporting Rhode Island's economy," U.S. Geological Survey Fact Sheet 2025–3018, USGS; a work of the United States government in the public domain. The fact sheet gives the total annual benefit as $178,560 in its text but as 178,560 thousand dollars in its table, so no dollar figures are given for Rhode Island here.
Licence: CC0 1.0 (public domain) · Adapted from pubs.usgs.gov
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