• stream ecology;
  • bathymetric lidar;

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 (