Improving Stream Studies With a Small‐Footprint Green Lidar

Abstract

Technology is changing how scientists and natural resource managers describe and study streams and rivers. A new generation of airborne aquatic‐terrestrial lidars is being developed that can penetrate water and map the submerged topography inside a stream as well as the adjacent subaerial terrain and vegetation in one integrated mission. A leading example of these new cross‐environment instruments is the Experimental Advanced Airborne Research Lidar (EAARL), a NASA‐built sensor now operated by the U.S. Geological Survey (USGS) [ Wright and Brock , 2002]. Standard airborne terrestrial lidars, which currently produce the highest‐resolution maps of extensive land areas, use reflected near‐infrared laser pulses to make millions of point measurements of ground and vegetation elevations. However, near‐infrared energy is absorbed by water, which limits the use of these systems to mapping features outside of water bodies. EAARL uses a narrow‐beam green, rather than near‐infrared, laser with a footprint of only 15 centimeters from the nominal flying height (for system technical specifications, see Table S1 in the electronic supplement to this Eos issue (http://www.agu.org/eos_elec/).