Lidar Elevation Data for Pennsylvania: The 3D Elevation Program

Publicly available lidar in Pennsylvania, March 2015. Only the southeast and a small central area met 3DEP's quality level 2 standard. USGS, from the U.S. Interagency Elevation Inventory.

Why elevation data matters

Elevation data underpin everything from forest and wildlife management to national security and recreation. In Pennsylvania they are critical for natural resources conservation — including the effects of oil and gas drilling — agriculture, flood risk management, infrastructure and construction, water supply and quality, and geologic hazards.

Pennsylvania already has statewide lidar. Federal, state and local agencies are working to replace older, lower-quality data with a newer, denser refresh of that coverage, to support the uses that better lidar makes possible.

What it's worth

• Benefits: at least $7.5 million a year in new benefits to the Commonwealth (conservative).
• Cost: about $15 million.
• Payback: 2.0 years; benefit/cost ratio 4.0 to 1 over 8 years.
• About 82% of the identified needs fall in conservation, agriculture and flood risk management.

Because not every benefit was given a dollar value, the true total is likely much higher.

How lidar helps Pennsylvania

Hidden hazards. Dense woods can hide danger. Bare-earth lidar models locate abandoned mine lands, track landscape change from oil and gas drilling, find active landslides and old ones that could move again, and detect sinkholes in karst that earlier elevation data missed — supporting public and environmental safety and site selection for industry. (The fact sheet illustrates this with an old but still active landslide in Clinton County.)

Shared state data. Governments, universities and businesses across the state save millions of dollars using the imagery, lidar and other data of PAMAP for work related to natural resource extraction — planning, permitting, design, environmental review, code enforcement and emergency response.

Floods. Lidar gives better, cheaper terrain for flood studies and hydrologic modeling; for designing bridges, culverts and dams to handle big storms; and for storm and wastewater engineering. Improved inundation models support floodplain decisions such as the early warnings of the Susquehanna Flood Forecast and Warning System, and help teach the public about flood risk.

About 3DEP

The National Enhanced Elevation Assessment (Dewberry, 2011) weighed options for data quality and how often to refresh it. The best return came 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 3DEP as the federal lead for land elevation data.

• Goal: complete national coverage by the end of 2022, depending on funding and partners — more accurate and current than the National Elevation Dataset.
• Value: conservatively $1.2 billion a year in new benefits nationally, with the potential for $13 billion a year — better government services, fewer crop and flood losses, more efficient vehicle routing and more.
• Why a national program: buying larger areas cuts costs by 25%; buying at higher quality avoids paying to "buy up" later; consistent data work across state and watershed lines; more federal money reduces what states and localities pay; and ready contracts and specifications simplify buying.

Sources

Based on William J. Carswell, Jr., "The 3D Elevation Program: summary for Pennsylvania," U.S. Geological Survey Fact Sheet 2015–3019 (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 landslide image, credited to a Pennsylvania state agency (the Pennsylvania Geological Survey), is not reproduced. The benefit figures come from Dewberry's National Enhanced Elevation Assessment (2011, revised 2012).