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Publicly available lidar in New Jersey, June 2014. USGS, from the U.S. Interagency Elevation Inventory.
All of New Jersey had public lidar by 2014, but mostly at quality level 3, below the standard of the USGS 3D Elevation Program (3DEP).
By the numbers
| Expected annual benefits | $16.08 million |
| Estimated total cost | $2.52 million |
| Payback | 0.2 years |
| Benefit/cost ratio (8 years) | 51 to 1 |
| Cost to buy up to quality level 1 | $1.60 million |
About 91% of the identified needs are in water supply and quality. The devastation of Hurricane Sandy in 2012 suggests the benefits for coastal management, sea-level rise, subsidence and flood risk are much higher than the survey recorded.
| Rank | Business use | Annual benefits (millions) |
|---|---|---|
| 1 | Water supply and quality | $14.66 |
| 2 | Flood risk management | 0.37 |
| 3 | Natural resources conservation | 0.28 |
| 4 | Agriculture and precision farming | 0.25 |
| 5 | Infrastructure and construction management | 0.18 |
| 6 | Coastal zone management | 0.14 |
| 7 | Sea level rise and subsidence | 0.10 |
| 8 | Aviation navigation and safety | 0.04 |
| 9 | Forest resources management | 0.04 |
| 10 | Geologic resource assessment and hazard mitigation | 0.01 |
| Other | 0.01 | |
| Total | 16.08 |
How lidar helps New Jersey
- Water quality. Runoff carries eroded soil, oil and grease, fertilizer, chemicals, pet waste and litter into waterways and groundwater recharge areas. Lidar-based models locate places in a watershed to store runoff temporarily, cutting peak flows and pollution; in cities they support wetland protection, impervious-surface mapping for stormwater plans and the rehabilitation of drainage systems.
- Floods. Lidar makes flood studies, retention-dam design, dam-breach studies and stormwater engineering more accurate and cheaper, pinpoints vulnerable properties in floodplains, and powers 3D models of flooding.
- Coast. After Sandy, repeated coastal lidar proved its worth for damage assessment and hazard mitigation planning.
Seaside Heights before (May 21, 2009) and after Hurricane Sandy (November 5, 2012); arrows mark the same structures. USGS photos.
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, managed by the USGS as the federal lead for land elevation data, chose an 8-year cycle, with the data made public.
| Quality level | Pulse spacing | Vertical error (RMSEz) |
|---|---|---|
| QL1 | 0.35 m | 10 cm |
| QL2 | 0.7 m | 10 cm |
| QL3 | 2.0 m | 20 cm |
| QL4 | — | 139 cm |
| QL5 (radar, Alaska) | — | 185 cm |
- Goal: operational by January 2015, national coverage by the end of 2022, depending on funding and partners.
- Value: conservatively $1.2 billion a year nationally, potentially $13 billion a year.
- Why a national program: larger purchases cut costs by 25%; buying high quality once avoids "buying up" later; data stay consistent across boundaries; federal money eases state and local shares; and ready contracts simplify buying.
Sources
Based on William J. Carswell, Jr., "The 3D Elevation Program: summary for New Jersey," U.S. Geological Survey Fact Sheet 2014–3091; a work of the United States government in the public domain. The map, photographs and tables are taken from the fact sheet's PDF. Benefit figures come from Dewberry's National Enhanced Elevation Assessment (2011, revised 2012).
Licenza: CC0 1.0 (pubblico dominio) · Tratto da pubs.usgs.gov
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