Lidar Elevation Data and Montana's Economy: The 3D Elevation Program

Montana is the fourth largest state in the country, at 147,040 square miles, and its terrain varies enormously. The western two-fifths lies in the Rocky Mountains and the eastern three-fifths in the Great Plains. Because the Continental Divide runs through it, Montana's rivers drain either to the Pacific Ocean or to the Gulf of Mexico. It is called the Treasure State for its mineral wealth of oil, gas and coal, but agriculture is its main economic activity. Other important work includes natural resources conservation, water supply and quality, infrastructure and construction management, flood risk management, and assessing geologic resources and hazards.

Much of that work depends on lidar (light detection and ranging): laser measurements that build a highly detailed three-dimensional model of the ground and everything standing on it.

The program

The 3D Elevation Program (3DEP) is run by the U.S. Geological Survey (USGS) with federal, state, Tribal, territorial and local partners. Its goal is the first national baseline of consistent, high-resolution elevation data, covering the country with lidar (with interferometric synthetic aperture radar, or IfSAR, in Alaska). Its products include bare-earth digital elevation models and 3D point clouds, the full set of collected points.

Baseline data must reach quality level 2 or better and meet version 1.2 or newer of the USGS Lidar Base Specification, with elevation models at a resolution of 1 meter or finer:

The USGS adds the data to The National Map, where they are free to download with no restrictions on use.

Status of 3DEP baseline lidar data in Montana as of October 2023. Data are available or in progress over most of the state, pending contributions are scattered, and one area in southeastern Montana has no baseline data. U.S. Geological Survey.

What the data are worth to Montana

The National Enhanced Elevation Assessment, published in 2012, surveyed what users needed and conservatively estimated that lidar data would bring Montana at least $13.08 million a year in new benefits. The estimated cost of finishing quality level 2 coverage is $8.30 million (higher-quality levels cost extra), a payback period of 0.63 year.

The Montana Lidar Plan (Montana State Library, 2019) aims for lidar coverage of the whole state. The data are used by federal, state, Tribal and local governments, businesses, nonprofits and the public.

Farming

Montana's agribusiness and related industries produced $4.3 billion in revenue in 2021, according to the Montana Department of Agriculture; wheat, hay, barley, lentils and dry peas are its most valuable crops. Lidar supports building and rebuilding levees, restoring wetlands, planning farms, modeling farmland in 3D for precision farming, and preventing soil erosion.

Flood mapping

For the Montana Department of Natural Resources and Conservation (DNRC), lidar is indispensable. Steve Story, chief of its Water Operations Bureau, explained in 2021 that new flood hazard maps meeting Federal Emergency Management Agency standards cannot be made at all without lidar bare-earth data, and that accurate flood-plain studies need quality level 2 data at least, preferably quality level 1. With quality level 2 data available, he said, the department had taken on mapping at a historic scale: more than half of the state's flood-plain mapping portfolio, about 8,000 stream miles, was being restudied. Updating flood hazard and risk is DNRC's primary mission, and he said it depends on that data.

Geology and hazards

The Montana Bureau of Mines and Geology (MBMG) is required to collect and publish information on the state's geology so that its energy, groundwater and mineral resources can be developed responsibly. Lidar has become essential to that work: for choosing places to do fieldwork, finding new areas for mineral discovery and locating old mine workings. Recent lidar has also revealed Quaternary faults and landslides no one had recognized before. In one example, a slope-shade map made from lidar traces the Quaternary-age Bitterroot fault running north–south across the Ward Creek fan in the southern Bitterroot Valley, offsetting several of the fan's surfaces.

Why a national program

The USGS points to several advantages of collecting elevation data nationally:

• economies of scale from acquiring larger areas at once
• predictable, flexible federal investment that lowers costs and makes planning easier
• consistent coverage for work that crosses project, jurisdictional and watershed boundaries
• simpler acquisition, with contracts, project management, quality assurance and published specifications already in place
• national benefits conservatively estimated at $690 million a year, with the potential for $13 billion a year more through uses across the economy

Federal, state, Tribal, territorial and local governments and private companies can take part. Partners can contribute funds to projects the USGS manages, or receive cooperative funding to run their own, and can pay to collect higher-quality data. Agreements are made through an annual Broad Agency Announcement, and organizations can also contribute existing data that meet 3DEP requirements.

Sources

• U.S. Geological Survey, "The 3D Elevation Program—Supporting Montana's economy," Fact Sheet 2023–3041. https://pubs.usgs.gov/publication/fs20233041/full
• Dewberry, National Enhanced Elevation Assessment (2012); Montana State Library, Montana Lidar Plan (2019); Montana Department of Agriculture (2022); Stickney and Lonn (2018). Lidar data: https://apps.nationalmap.gov/downloader/; Lidar Base Specification: https://www.usgs.gov/3dep/lidarspec
• Steve Story's written communication of November 10, 2021, is paraphrased here. The fact sheet's slope-shade map of the Bitterroot fault is credited to the Montana Bureau of Mines and Geology and is not reproduced.
• Words on this page from people and organisations outside the federal government are paraphrased; rewritten in hubnx's own words.