Publicly available lidar in Nebraska, March 2015. USGS, from the U.S. Interagency Elevation Inventory.
Why elevation data matters
In Nebraska, elevation data are most valuable for agriculture and precision farming, conservation, flood risk management, infrastructure and geologic hazards. 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 | $11.10 million |
| Estimated total cost | $25.84 million |
| Payback | 2.3 years |
| Benefit/cost ratio (8 years) | 3.4 to 1 |
| Cost to buy up to quality level 1 | $16.44 million |
About 86% of the identified needs fall in agriculture and conservation; 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 | $6.34 |
| 2 | Natural resources conservation | 3.18 |
| 3 | Flood risk management | 0.63 |
| 4 | Infrastructure and construction management | 0.46 |
| 5 | Geologic resource assessment and hazard mitigation | 0.14 |
| 6 | Water supply and quality | 0.14 |
| 7 | Aviation navigation and safety | 0.10 |
| 8 | Renewable energy resources | 0.10 |
| 9 | River and stream resource management | 0.01 |
| 10 | Homeland security, law enforcement and disaster response | 0.00 |
| Total | 11.10 |
How lidar helps Nebraska
Precision farming. About 46% of Nebraska is cropland. More accurate terrain improves precision farming — raising yields, preventing soil loss and cutting chemical runoff, so farmers get a better return.
Floods. 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 finding vulnerable properties in floodplains.
Water quality. Lidar-based models of watersheds, catchments and wetlands support wellhead protection and land management that reduces risks to water quality. They can pinpoint places in a watershed where runoff could be stored temporarily to cut peak flows and the sediment and nutrients it carries, and support wetland preservation and the restoration of waterways.
Filter strips used with terraces in Sarpy County keep sediment and other contaminants out of nearby waterways. Photograph courtesy of the USDA Natural Resources Conservation Service.
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., "3D Elevation Program: summary for Nebraska," U.S. Geological Survey Fact Sheet 2014–3112, version 1.1 (2015); a work of the United States government in the public domain. The map, photograph and tables are taken from the fact sheet's PDF. Benefit figures come from Dewberry's National Enhanced Elevation Assessment (2011, revised 2012).
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