Lidar Allows Sandy River to be Mapped30/05/2013
|In September 2012, Watershed Sciences, Inc. (WSI) and Dewberry collected airborne topobathymetric Lidar data for the Sandy River in Oregon, USA. These data are being used to map channel and floodplain morphology and to evaluate the effectiveness of RIEGLís VQ-820-G hydrographic airborne scanner in a Pacific Northwest riverine environment. The shallow river system - including side-channel and off-channel areas that are notoriously difficult to measure using conventional techniques - was successfully mapped using Lidar.|
The Sandy River in northwestern Oregon is a shallow river running from Reid Glacier on Mount Hood for 56 miles to the Columbia River and flows through areas of steep terrain and dense forest. The nature of the river makes it challenging for traditional transect or boat-based bathymetric surveys. The RIEGL VQ-820-G sensor was selected for its pulse repetition rate, short pulse width, and narrow beam divergence.
The VQ-820-G was mounted in WSI’s Cessna Caravan and flown at 600 metres above ground level with 50% overlap between flight lines. With a flying speed of 105 knots, 7,000 acres of topo-bathymetric surfaces were mapped in less than 6 hours at a pulse density of 6 points per square metre. Analysis involved post processing and further line-to-line calibration to match collected ground survey data. Laser returns from water were corrected for refraction using software developed by Dewberry that utilised an extracted water surface. A depth model was calculated along with a confidence layer to assess depth penetration, coverage, and accuracy.
The clarity in the Sandy River was measured at a 2 metre Secchi depth on the day of the survey. With RIEGL advertising a depth finding range of 1 Secchi depth, it was expected that the majority of the river channel would be mapped. The mapped area was divided into high and low confidence categories based on density of bathymetric returns. High confidence areas accounted for 83% of the mapped channel and had a vertical accuracy of 0.18 metre RMSE when compared against channel cross section data. However, the accuracy of ground data collection was hindered by difficult wading conditions and GPS masking (terrestrial returns had a 0.03 metre RMSE).
Overall, the project produced encouraging results for the utilisation of small footprint, topobathymetric Lidar for mapping channel floodplains and shallow water river systems. WSI and Dewberry have received strong positive feedback from project partners about the results of the survey and the future opportunities of airborne hydrographic scanning.
Contributing partners for the test project were the Oregon Department of Geology and Mineral Industries, the Federal Emergency Management Agency and Bureau of Land Management.
comments powered by Disqus
Read more about:
data Environment Lidar mapping software
Supplier: RIEGL Laser Measurement Systems GmbH
More news from this supplier:
RIEGL LiDAR 2015: Abstracts Sought
Double RIEGL LIDAR 2015 User Conference
RIEGL Opens Sales Office in Beijing
Award for Hydrographic Lidar Scanner
Riegl and Applanix Integrate on UAV
RIEGL at US Hydro
Laser Mapping Technology at Ocean Business
Hydrographic Airborne Scanner Integrated in UAV
Geospatial Excellence Award for RIEGL
Demo of Hydrographic Airborne Laser Scanning System
Planet Ocean Team with dotOcean
Second Cougar for Tidal Renewable Energy Installers
Call for Abstracts for OI China 2015 and OI 2016
Teledyne Technologies Fully Owns Optech Shares
Optech at AUVSI Unmanned Systems 2015
The ECDIS Revolution Confirmed
Wello Extends Penguin Wave Energy Converter Tests at EMEC
ULS-500 Underwater Laser Scanner Interface for QINSy
Introduction to Inertial Navigation
Technical Workshops by Fugro during Offshore Technology Conference
Teledyne BlueView 3D Scanning Sonar in Use for Inspections
Teledyne BlueView 3D scanning sonar is used in infrastructure inspection such as post scour remediation inspection. Infrastructure managers verify construction was completed to contract specifications and for pre-construction inspection to assist with project planning.