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/).

Making riverscapes real

“…Terrestrial-based LiDAR can be used over short distances (reach-scales) to measure high-resolution topography and estimation of particle sizes from mm-scale topographic maps (Hodge et al, 2009a,b). A few groups have experimented with bathymetric LiDAR; a technology that uses active green wavelength LiDAR technology to detect the water surface and the channel-bottom (McKean et al, 2008(McKean et al, , 2009a.…”

Remote sensing of rivers: the emergence of a subdiscipline in the river sciences

“…Developing automated techniques as part of stand-alone software or as plug-ins for existing software will go a long way towards enabling managers and river scientists to use the techniques. Authors have recently begun to make advances in this direction (Dugdale and Carbonneau, 2009;McKean et al, 2009;Wheaton et al, 2009), but the large majority of river remote sensing techniques remain inaccessible to many river scientists and to most river managers.…”

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“…This evolution constitutes a highly variable spatial process and, depending on selection of time intervals, spatial units, and data aggregation methods, differing or even quite opposite trends can be derived (Burroughs and Tebbens, 2008;Zhou and Xie, 2009). Complex spatial and temporal patterns of elevation change have been observed for stream channels (McKean et al, 2009) and for disturbed landscapes exposed to severe erosion (Kincey and Challis, 2009). To adequately understand the mechanisms that govern landscape evolution, these processes need to be monitored at different spatial extents, spatial resolutions, and temporal scales.…”