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Existing and planned public lidar in Wyoming, October 2014. USGS, from the U.S. Interagency Elevation Inventory.
Why elevation data matters
In Wyoming, elevation data are critical for geologic hazards, flood risk management, water supply and quality, conservation and agriculture. Federal, state, tribal and local agencies work together to replace older lidar and fill gaps, aiming for consistent statewide coverage.
By the numbers
| Expected annual benefits | $6.19 million |
| Estimated total cost | $32.66 million |
| Payback | 5.3 years |
| Benefit/cost ratio (8 years) | 1.5 to 1 |
| Cost to buy up to quality level 1 | $20.78 million |
About 72% of the identified needs fall in conservation, agriculture and infrastructure. State officials later said the benefits for geologic hazards and flood risk management were probably underestimated, and because not every benefit had a dollar value, the true total is likely higher.
| Rank | Business use | Annual benefits (millions) |
|---|---|---|
| 1 | Natural resources conservation | $2.63 |
| 2 | Agriculture and precision farming | 0.99 |
| 3 | Infrastructure and construction management | 0.82 |
| 4 | Water supply and quality | 0.57 |
| 5 | Geologic resource assessment and hazard mitigation | 0.40 |
| 6 | Flood risk management | 0.30 |
| 7 | Forest resources management | 0.20 |
| 8 | Renewable energy resources | 0.10 |
| 9 | Aviation navigation and safety | 0.09 |
| 10 | River and stream resource management | 0.05 |
| Other | 0.04 | |
| Total | 6.19 |
How lidar helps Wyoming
Landslides and faults. Lidar terrain models reveal faults and landslide-prone ground. In spring 2014, a landslide in Jackson, near Broadway Avenue and Budge Drive at the foot of East Gros Ventre Butte, cracked and shifted homes, retaining walls, pavement and curbs — part of one house sheared off at the landslide's head scarp. Remediation was estimated at about $7.5 million.
Floods. From 1905 to 2010, Wyoming's flood losses averaged $3.7 million a year (in 2010 dollars). Lidar gives better, cheaper terrain for flood studies and hydrologic modeling; for designing bridges and culverts; for dam design, dam-breach studies and stormwater engineering; and for identifying vulnerable properties in floodplains and showing the public their true risk.
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 chose an 8-year cycle. The USGS runs it as the federal lead for land elevation data.
| 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 Wyoming," U.S. Geological Survey Fact Sheet 2014–3108, version 1.1 (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 photograph of the Budge Drive landslide, courtesy of the Wyoming State Geological Survey, is not reproduced. Benefit figures come from Dewberry's National Enhanced Elevation Assessment (2011, revised 2012).
Licença: CC0 1.0 (domínio público) · Adaptado de pubs.usgs.gov
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