Monday, September 28, 2015

The Benefits of Improved National Elevation Data

National elevation data is extremely useful in areas such as flood hazard mitigation, agricultural productivity, infrastructure and energy development, resource conservation, and national security.  The National Digital Elevation Program (NDEP) was created to meet the needs of the government and industry for digital elevation models.  The program includes numerous federal agencies such as the USGS, the Census Bureau, and numerous agencies within the Department of the Interior.  In general, elevation data updates come for areas every 30 years, while the technology grows at a much faster pace.  At the time of this writing, the elevation data needs of the United States were not being met, so a task force was created to assess the potential for improving the national elevation data.  The National Enhanced Elevation Assessment (NEEA) was conducted in 2011 to assess the current needs for improved elevation data, assess the costs and benefits of improving data, and evaluate new models.
The benefits of improved data are many, and their significance cannot always be captured by a dollar value.  For example, improved elevation data can eliminate the need for survey crews when constructing new roads, which eliminates deaths to survey crews that occur yearly.  A larger-scale example occurred in Washington, where improved elevation modeling helped discover a fault near the Tacoma Narrows that led to an over $700 million bridge repair.  As recently as 2014, President Obama declared that the National Digital Elevation Program would be used as part of the Climate Action Plan to locate which areas will be most affected by climate change.  Improved data can also be used for siting wind farms, directing agricultural runoff, and constructing efficient oil and water pipeline paths.  The research of the NEEA also showed that technology is at a stage of growth where it makes sense from a cost standpoint to engage in updating the digital elevation models.

The assessment determined that the benefits of improving the national elevation models outweigh the costs by a large factor.  There are several different levels of elevation data quality that can be used, however, and each quality level comes with a corresponding level of benefits that can accrue at each level of precision.  Each quality level except for the very highest comes with a net benefit to the US, and at ratios greater than 4:1.  Figure 1 shows the relative image quality of the highest three quality levels, and Figure 2 shows the cost/benefit analysis of quality levels ranging from highest to lowest levels of improvements.  The assessment ultimately led to the creation of the 3D Elevation Program (3DEP), which is now in the process of being implemented.  Federal and state agencies work together along with others to improve the elevation using light detection and ranging (LIDAR) and interferometic synthetic aperture data (IFSAR) which is used specifically for data in Alaska.  Data will be collected on 8 year cycles, and annual benefits from a fully funded program would be $690 million.  The 3DEP receives $50 million annual now, and needs an additional $96 million annually to be fully implemented.  This relatively small investment could lead to huge savings over time, especially in case of disasters.  Improved elevation data leads to better emergency flood mitigation plans, better preparedness for impacts of climate change, and increased operating efficiency and capacity.  Watch for annual improvements in the coming years from 3DEP.  The program’s website is:

Snyder, G. I. (2013). The benefits of improved national elevation data.Photogrammetric Engineering and Remote Sensing79(2).

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