Mapping River Bathymetry with Green Lidar

Airborne bathymetric lidar systems designed for coastal and marine surveys are increasingly sought after for high-resolution mapping of fluvial systems. To evaluate the potential utility of bathymetric lidar for applications of this kind, we compared detailed surveys collected using wading and sonar techniques with measurements from the USGS hybrid topographic ⁄ bathymetric Experimental Advanced Airborne Research Lidar (EAARL). These comparisons, based upon data collected from the Trinity and Klamath Rivers, California, and the Colorado River, Colorado, demonstrated that environmental conditions and post-processing algorithms can influence the accuracy and utility of these surveys and must be given consideration. These factors can lead to mapping errors that can have a direct bearing on derivative analyses such as hydraulic modeling and habitat assessment. We are examining the water and substrate characteristics of the sites, comparing the conventional and remotely sensed riverbed topographies, and investigating the laser waveforms reflected from submerged targets to evaluate the suitability and accuracy of the EAARL system and associated processing algorithms for riverine mapping applications.