New airborne mapping technology known as light detection and ranging has been used to accurately map land surface elevations across more than half of New Hampshire, from Massachusetts to Quebec. This major data collection project was a partnership between the state of New Hampshire, U.S. Geological Survey, USDA Natural Resources Conservation Service, Federal Emergency Management Agency, and the White Mountain National Forest.
Data collected during the fall in 2015 has now been fully processed and reviewed and is ready for release.
The project footprint adjoins several areas of the state where LiDAR data already exist with an additional 5,200 square miles along the Connecticut River and around Lake Winnipesaukee. As a result of this project, enhanced elevation data is now available for 84 percent of the state and can be obtained from the spatial data clearinghouse at http://lidar.unh.edu.
A contract is currently in place to acquire LiDAR data for the remaining area and complete statewide coverage.
Accurate, high-resolution data on land surface elevations and contours (topography) are critical for mapping the extent of areas impacted by river flooding as well as numerous other economic development and natural resource applications. Before LiDAR, topographic maps produced decades ago by the USGS were the most commonly used source of elevation data for engineers and other resource professionals. However, the elevation contour lines on these maps too inaccurate to support modern computerized mapping methods.
LiDAR technology has been proven to provide a vertical accuracy of +/- 6 inches, and has become the widely accepted standard for acquiring elevation data over large geographic areas.
The mapping is performed using a rapidly pulsing laser that is directed toward the ground from an airplane flying 180 mph in a straight line at an altitude of over a mile. Because LiDAR can “see” the ground even when it is covered by trees, the method is ideal for mapping in heavily forested areas like much of New Hampshire.
For more information, contact N.H. State Geologist Rick Chormann at 271-1975 or Frederick.Chormann@des.nh.gov.