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Publicly available lidar in Michigan, March 2015. USGS, from the U.S. Interagency Elevation Inventory.
By the numbers
| Expected annual benefits | $10.19 million |
| Estimated total cost | $19.39 million |
| Payback | 1.9 years |
| Benefit/cost ratio (8 years) | 4.2 to 1 |
| Cost to buy up to quality level 1 | $12.34 million |
About 72% of the identified needs fall in agriculture, conservation and flood risk management; since not every benefit had a dollar value, the true total is likely higher.
| Rank | Business use | Annual benefits (millions) |
|---|---|---|
| 1 | Agriculture and precision farming | $3.16 |
| 2 | Natural resources conservation | 2.93 |
| 3 | Flood risk management | 1.27 |
| 4 | Water supply and quality | 0.75 |
| 5 | Infrastructure and construction management | 0.72 |
| 6 | Coastal zone management | 0.69 |
| 7 | Forest resources management | 0.36 |
| 8 | Aviation navigation and safety | 0.13 |
| 9 | Geologic resource assessment and hazard mitigation | 0.11 |
| 10 | Renewable energy resources | 0.03 |
| Other | 0.04 | |
| Total | 10.19 |
How lidar helps Michigan
- Farming. About 28% of Michigan is farmland. Better terrain data improve precision farming — higher yields, less soil loss and less chemical runoff.
- Conservation. Governments could do less fieldwork for grade stabilization, ponds, grassed waterways, terracing and wetland delineation and restoration, saving public money.
- Geology. Lidar shows subtle features missing from topographic maps and aerial photos. The fact sheet compares a 1980 USGS map of Northwest Albion in Calhoun County with lidar relief that reveals eskers — ridges of glacial gravel, often valuable sources of gravel. Lidar has fundamentally changed geologic mapping.
About 3DEP
The National Enhanced Elevation Assessment (Dewberry, 2011) found the best return from quality level 2 lidar for the conterminous United States and quality level 5 radar (ifsar) for Alaska, refreshed every 6 to 10 years. 3DEP, run by the USGS as the federal lead for land elevation data, chose an 8-year cycle, covering the conterminous United States, Hawaii and the territories with lidar and Alaska with radar, and making the data public.
| Quality level | Pulse spacing | Vertical error (RMSEz) |
|---|---|---|
| QL1 | 0.35 m | 10 cm |
| QL2 | 0.7 m | 10 cm |
| QL3 | 1.4 m | 20 cm |
| QL4 | — | 139 cm |
| QL5 (radar, Alaska) | — | 185 cm |
- Goal: complete national coverage by the end of 2022, depending on funding and partners.
- Value: conservatively $1.2 billion a year nationally, with the potential for $13 billion a year.
- Why a national program: larger purchases cut costs by 25%; buying high quality once avoids paying to "buy up" later; consistent data across state and watershed lines; more federal money reduces state and local shares; and ready contracts and specifications simplify buying.
Sources
Based on William J. Carswell, Jr., "The 3D Elevation Program: summary for Michigan," U.S. Geological Survey Fact Sheet 2014–3107, version 1.2 (2015); a work of the United States government in the public domain. The map and tables are taken from the fact sheet's PDF; its lidar comparison image, courtesy of the Michigan Geological Survey, is not reproduced. Benefit figures come from Dewberry's National Enhanced Elevation Assessment (2011, revised 2012).
Licence : CC0 1.0 (domaine public) · Adapté de pubs.usgs.gov
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