UBC Theses and Dissertations
A rapid and objective characterization of channel morphology in a small, forested channel using a remotely piloted aircraft. Helm, Carina
The use of remotely piloted aircrafts (RPAs) in fluvial geomorphology has improved the ability to characterize streams at greater resolutions and spatial extents than was previously attainable using traditional survey techniques. However, their use has been generally limited to streams under ideal conditions that differ from the small, forested mountain channels common in the Pacific Northwest. These channels have remained difficult to characterize using modern techniques due to their dense canopies and rough terrain. A rapid and objective method of characterizing channel morphology across the river basin using a RPA is presented in this dissertation to help overcome this challenge. First, the accuracy of RPAs for extracting bed elevations, bathymetry and grain size along 3 km of Carnation Creek, a small, forested stream on Vancouver Island, was investigated through a sub-canopy survey. Relevant cross-sectional channel variables were then extracted to objectively characterize channel morphologies across the river basin using a principal component analysis-clustering (PCA-clustering) technique. Then the Shannon's diversity index was used to characterize the local diversity across the channel, and investigate the scale needed to study the system, to ensure its heterogeneity was characterized. The results demonstrate that RPAs provide a rapid alternative to characterizing these systems, through the construction of a 2-cm resolution digital elevation model spanning 3 km of channel, with a root-mean-square-error of 0.093 m for exposed bed check points and 0.1 m for submerged bed check points. The PCA-clustering analysis provided an objective means of classifying channel morphology with a correct classification rate of 85%. Altogether, the results provide a precedent for using a RPA to characterize the morphology and diversity of small, forested channels at a scale of ecological relevance to the life histories of Pacific salmonids.
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