Mapping riverine habitats of the Delaware River using bathymetric LiDAR

Science Center Objects

Ecosystem management and assessment of rivers requires detailed data on bathymetry before estimates of aquatic habitats can be determined. However, mapping bathymetry in shallow rivers is challenging due to river depth limitations for watercraft.  Light detection and ranging (LiDAR) technology has revolutionized aerial mapping of topography and vegetation, but the infrared lasers used on these systems can’t penetrate water and are therefore unsuitable for river mapping. However, recently developed LiDAR systems that use green light lasers hold promise for aerial mapping of river bathymetry We conducted a research project to test the implementation of this technology on the upper Delaware River. While we are finding some limitations due to depth, substrate, and water clarity, results suggest that this technology holds promise for mapping large stretches of clear, shallow rivers.

Objectives of this project were to test the capability of an aerial bathymetric LiDAR system (EAARL-B) for mapping a large stretch (196 km, 122 miles) of the Delaware River (USA).   We acquired, processed are evaluating this data through comparison with boat-based dual-beam sonar depth mapping and wading elevation surveys using RTK-GPS at 14 river access locations throughout the mapped area. While quantifying differences with boat-based sonar depth mapping is problematic, the bathymetric lidar derived elevations compare well with RTK GPS elevations (RMSE 0.244m overall), although differences in mapping accuracy by bottom substrate are evident. 

Collection of RTK-GPS and boat-based sonar on the upper Delaware River

Field data to validate the bathymetric LiDAR was collected by RTK-GPS wading surveys and boat-based sonar at 14 river access sites.

(Credit: John Young, USGS Leetown Science Center. Public domain.)

Bathymetric LiDAR mapping result.

A section of the Delaware River near Callicoon, NY showing results of bathymetric mapping using the EAARL-B green light LiDAR system.  Laser pulses from the EAARL-B were georeferenced, corrected for water refraction, filtered to remove above ground objects (i.e. bridges), mapped as x,y,z elevations, and merged with other data.

(Credit: John A. Young, USGS Leetown Science Center. Public domain.)