High-resolution interpretative geomorphological mapping of river valley environments using airborne LiDAR data

The availability of airborne LiDAR data provides a new opportunity to overcome some of the problems associated with traditional, field-based, geomorphological mapping such as restrictions on access and constraints of time or cost. The combination of airborne LiDAR data and GIS technology facilitates the rapid production of geomorphological maps of floodplain environments; however, unfiltered LiDAR data, which include vegetation and buildings, are currently more suitable for geomorphological mapping than data that have been filtered to remove these features. Classification of LiDAR data according to elevation in a GIS enables the user to identify and delineate geomorphological features in a manner similar to field mapping, but it is necessary to use a range of classification intervals in order to map the various types of feature that occur within a single reach. Comparison of a LiDAR-derived geomorphological map with an independently produced field geomorphological map showed a high degree of similarity between the results of the two methods, although ground-truthing is essential in cases where a high degree of accuracy is required. Ground-truthing of a LiDAR-derived geomorphological map showed that around 80% of features mapped using both methods were identified from the LiDAR data, suggesting that the method is suitable for applications such as production of base maps for use in field mapping and selection of sites for detailed investigation.