# National Enhanced Elevation Assessment

Introduction

3D elevation data are essential for flood mitigation, conservation management, infrastructure development, national security, and many other applications. The National Enhanced Elevation Assessment (NEEA) was conducted to (1) document national level requirements for enhanced elevation data, (2) estimate the benefits and costs of meeting those requirements, and (3) evaluate multiple national enhanced elevation program scenarios.

Benefits of a National 3D Elevation Program

The National Enhanced Elevation Assessment (NEEA) documented business uses for elevation needs across 34 Federal agencies, agencies from all 50 States, selected local government and Tribal offices, and private and not-for profit organizations. Each need was characterized by the following:

• Data accuracy
• A refresh cycle for the data
• Coverage for geographic areas of interest

Each business activity was described and the expected benefits derived from enhanced elevation data were identified wherever possible. When benefits were expressed as a range of values, the lower number represented the conservative benefit and the higher number represented the potential benefit.

Ranking of Business Uses for Elevation Needs

1. Flood risk management - annual benefit of $295 million dollars (conservative), 502 million dollars (potential) 2. Infrastructure and construction management - annual benefit of$206 million dollars (conservative), 942 million dollars (potential)
3. Natural resources conservation - annual benefit of $159 million dollars (conservative), 225 million dollars (potential) 4. Agriculture and precision farminh - annual benefit of$122 million dollars (conservative), 2,011 million dollars (potential)
5. Water supply and quality - annual benefit of $85 million dollars (conservative), 156 million dollars (potential) 6. Wildfire management, planning and response - annual benefit of$76 million dollars (conservative), 159 million dollars (potential)
7. Geologic resource assessment and hazard mitigation - annual benefit of $52 million dollars (conservative), 1,067 million dollars (potential) 8. Forest resources management - annual benefit of$44 million dollars (conservative), 62 million dollars (potential)
9. River and stream resource management - annual benefit of $38 million dollars (conservative), 87 million dollars (potential) 10. Aviation navigation and safety - annual benefit of$35 million dollars (conservative), 56 million dollars (potential)

Analysis and Program Scenarios

Benefit-cost analyses were developed and examined for more than 25 program scenarios. Each scenario included a different data- quality level and data refresh cycle- combination. Ten leading scenarios emerged from this analysis.

The estimated costs for each scenario include those for data collection and life-cycle management. The scenario outlined in red is a middle-range option that offers uniform medium- to high-quality light detection and ranging (lidar) data for 49 States and U.S. territories and interferometric synthetic aperture radar (IfSAR) data for Alaska. These data would be acquired over an 8-year period and address 58 percent of the benefits associated with the requirements identified in the NEEA.

Benefit-cost analyses were developed and examined for more than 25 program scenarios. (Public domain.)

Elevation Data Inventory

An inventory of known high-resolution digital elevation data sources was conducted as part of the NEEA in the summer of 2011. The inventory was completed by the U.S. Geological Survey's Geospatial Liaisons in cooperation with the National Oceanic and Atmospheric Administration and the Federal Emergency Management Agency. The inventory included publicly available enhanced elevation data for any area where the coverage was complete for a county or was at least 300 square miles in size.

The following is an overview of the results of the inventory:

• Lidar data have been collected over 28 percent of the conterminous United States and Hawaii.
• IfSAR data have been collected over approximately 15 percent of Alaska.
• Elevation data was collected at an average annual rate of 4 to 5 percent from 2009-2011.
• The level of overlapping coverage is less than 10 percent.
• The quality of the data varies from project to project.

The following maps resulted from the inventory:

• The Elevation Data 2011 Inventory may be downloaded as a zipped Shapefile here

Since the NEEA Study, the inventory has been updated annually, and has evolved into the U.S. Interagency Elevation Inventory (USIEI). More information can be found on the U.S. Interagency Elevation Inventory webpage.

Partners in NEEA Study

The NEEA was conducted under a contract between the U.S. Geological Survey and Dewberry (a consulting firm based in Fairfax, Va.). Additional support for the assessment came from other Federal agencies: the Federal Emergency Management Agency, the National Geospatial-Intelligence Agency, the National Oceanic and Atmospheric Administration, and the Natural Resources Conservation Service.

NEEA Resources