Coveney, Seamus and Fotheringham, Stewart and Charlton, Martin and McCarthy, Tim
(2010)
Dual-scale validation of a medium-resolution coastal DEM with terrestrial
LiDAR DSM and GPS.
Computers and Geosciences, 36 (4).
pp. 489-499.
ISSN 0098-3004
Abstract
The use of medium-resolution photogrammetric-derived Digital Elevation Models (DEMs) to model
coastal inundation risk is commonplace in the geosciences. However, these datasets are often
characterised by relatively large and loosely defined elevation errors, which can seriously limit their
reliability. Post-processed and static RTK dual-frequency GPS data and very high-resolution Terrestrial
Laser Scanning DSM data are used here to quantify the magnitude and spatial distribution of elevation
error on a 10 km coastal section of a medium-resolution photogrammetric DEM. The validation data are
captured at two scales and spatial-resolutions to minimise the risk of spatial bias in the validation
results. The strengths and shortcomings of each validation dataset are assessed, and the complimentary
value of GPS and Terrestrial Laser Scanning for external validation is demonstrated. Elevation errors
highlighted in the photogrammetric DEM are found to be significantly larger than suggested by the data
suppliers, with a tendency for the larger errors to occur with increasing proximity to the coastline. The
results confirm the unsuitability of the DEM tested for the local spatial modelling of coastal inundation
risk, highlighting difficulties that may be prone to occur when similar DEM datasets are used in coastal
studies elsewhere.
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