Fairfax, Va. — Dewberry announced that mapping efforts under the Alaska Statewide Digital Mapping Initiative (SDMI) have surpassed the 50 percent mark, with new maps now complete for many of the state’s high-priority areas. Recent achievements include the recording of a revised elevation for Denali (formerly Mount McKinley) in Denali National Park.
Dewberry, as prime consultant to the U.S. Geological Survey (USGS) under its Geospatial Products and Services contract, began mapping Alaska in 2010 to assist the state in updating its map data and creating a new series of digital elevation models (DEMs). The initiative followed a 2008 study prepared by Dewberry that examined the lack of reliable digital elevation data and explored options to update the state’s inventory of USGS topographic maps.
“As of 2008, when we began working in Alaska, no maps of Alaska had ever been compiled, at any scale, to National Map Accuracy Standards,” says Dave Maune, Ph.D., a senior manager leading the SDMI project for Dewberry. “Most maps were deficient, making it difficult to manage the state’s natural resources and infrastructure, and creating perilous conditions for pilots.”
Dewberry’s study recommended interferometric synthetic aperture radar (IFSAR), a digital mapping technology that operates day and night and can map rugged terrain through heavy fog and cloud coverage. USGS contracted Dewberry, along with subconsultants Intermap Technologies and Fugro EarthData Inc., to begin mapping the state with IFSAR, subject to the availability of funds. To date, IFSAR data has been collected for more than 319,000 square miles, with nearly 60 percent of the state now re-mapped including the Copper River region and Glacier Bay National Park and Preserve.
Among the SDMI’s recent milestones, a team of surveyors under Dewberry management recently scaled the summit of Denali, the highest point in North America, to secure a new elevation using modern GPS survey equipment. The previous elevation of 20,320 feet has now been revised to 20,310 feet. While a 2013 elevation obtained through IFSAR was calculated at a lower elevation, Dewberry had recommended a GPS survey as more accurate than IFSAR in gauging the elevation of a summit. “IFSAR has been remarkably useful in obtaining digital elevation data throughout Alaska given the technology’s ability to map through fog and clouds,” says Maune. “But its application is limited in situations where there are steep slopes. The 2013 IFSAR data did reveal several new ridgelines in Alaska that had never been mapped, but we weren’t convinced of its accuracy for Denali itself.”
Maune helped assemble a team from Colorado-based CompassData, a firm with experienced surveyors who had climbed Denali several times. Three CompassData employees were joined by a scientist from the University of Alaska-Fairbanks for the climb, which involved carrying extensive GPS equipment and supplies to the summit. The trip was sponsored by USGS and the National Oceanic and Atmospheric Administration’s National Geodetic Survey (NGS). USGS announced the revised elevation on September 2.
“With the leadership and support of USGS, Alaska is making great strides toward acquiring comprehensive and accurate digital elevation data to update its maps,” says Maune. “This will not only benefit pilots across Alaska, but it will help in managing natural resources, maintaining infrastructure, preparing for natural disasters, economic development, and many other aspects of managing the state.”