Comparison of New Technologies for Mapping Bathymetry for Use in Hydrodynamic Models

Management of aquatic ecosystems can be enhanced by fine-scale bathymetric maps; however traditional methods for data collection are resource intensive and spatially limited.  Low cost side-scan sonar (e.g. Humminbird) and airborne bathymetric LiDAR technologies (e.g. USGS EAARL-B sensor) may improve data collection by decreasing time and resource investment while potentially yielding comparable or improved quality.  We first assessed accuracy, resolution and agreement of each sensor’s data and tested how bed files generated from each sensor affected hydrodynamic models.  Preliminary evaluations indicate high spatial agreement between the two sensors and good accuracy (±0.25m) between both sensors and RTK point elevations.  Hydrodynamic models indicate similarities in data collection technologies, but differences in data point spacing.  Sonar spatial coverage is limited to boat tracks while LiDAR collects many points across a large spatial area.  Sonar was useful for measuring water depths down to 30m, while LiDAR was useful only at depths <8m, although both had limited utility at shallow depths (< 0.15m).  Our findings indicate these technologies can be useful in development of bathymetric maps and hydraulic modeling.  Their combined use may produce a more accurate river bed depiction.