UAS‐based remote sensing of fluvial change following an extreme flood event

Abstract

The effects of large floods on river morphology are variable and poorly understood. In this study, we apply multi‐temporal datasets collected with small unmanned aircraft systems (UASs) to analyze three‐dimensional morphodynamic changes associated with an extreme flood event that occurred from 19 to 23 June 2013 on the Elbow River, Alberta. We documented reach‐scale spatial patterns of erosion and deposition using high‐resolution (4–5 cm/pixel) orthoimagery and digital elevation models (DEMs) produced from photogrammetry. Significant bank erosion and channel widening occurred, with an average elevation change of −0.24 m. The channel pattern was reorganized and overall elevation variation increased as the channel adjusted to full mobilization of most of the bed surface sediments. To test the extent to which geomorphic changes can be predicted from initial conditions, we compared shear stresses from a two‐dimensional hydrodynamic model of peak discharge to critical shear stresses for bed surface sediment sizes. We found no relation between modeled normalized shear stresses and patterns of scour and fill, confirming the complex nature of sediment mobilization and flux in high‐magnitude events. However, comparing modeled peak flows through the pre‐ and post‐flood topography showed that the flood resulted in an adjustment that contributes to overall stability, with lower percentages of bed area below thresholds for full mobility in the post‐flood geomorphic configuration. Overall, this work highlights the potential of UAS‐based remote sensing for measuring three‐dimensional changes in fluvial settings and provides a detailed analysis of potential relationships between flood forces and geomorphic change. Copyright © 2015 John Wiley & Sons, Ltd.

Application of Low-Cost Fixed-Wing UAV for Inland Lakes Shoreline Investigation

“…Using UAVs is now widespread across a range of disciplines (Anderson and Gaston 2013;Liu et al 2014;Smith et al 2016). The most popular environmental applications are: landslide monitoring (Lucieer et al 2014a), measuring changes in coastal morphology (Casella et al 2014;Gonçalves and Henriques 2015;Papakonstantinou et al 2016), monitoring glacier movement (Immerzeel et al 2014;Ryan et al 2015), studying Antarctic moss beds (Lucieer et al 2014b), soil erosion monitoring (d'Oleire-Oltmanns et al 2012), fluvial geomorphology (Mori et al 2002;Tamminga et al 2015;Woodget et al 2015) and forest research (Tang and Shao 2015;Wallace et al 2012). These studies are conducted using different UAV platforms delivered by various manufacturers (i.e., hybrid, flapping-wing, fixed-wing, coaxial, duct-fan, single rotor, and multi-rotor).…”

Review article: the use of remotely piloted aircraft systems (RPASs) for natural hazards monitoring and management

“…In the case of flood monitoring by image-based photogrammetry, however, areas under water are often problematic because the bed is not often fully seen in aerial images. If the water is clear enough, bed images under water can be captured, and the bed morphology can be measured with additional corrections of refraction (Tamminga et al, 2015;Woodget et al, 2015), but the floodwater is often unclear because of the abundant suspended sediment and disruptive flow current. Another option is the fusion of different data sets using a sonar-based measurement for the water-covered area, which is registered with the terrestrial data sets (Flener et al, 2013;Javernick et al, 2014).…”

“…RPASs have great potential to provide enhanced flexibility for positioning and repeated data collection. Tang and Shao (2015) summarize various approaches of remote drone sensing, surveying forests, mapping canopy gaps, measuring forest canopy height, tracking forest wildfires and supporting intensive forest management. These authors underlined the usefulness of drones for wildfire monitoring.…”

Application of UAV-SfM photogrammetry and aerial lidar to a disastrous flood: repeated topographic measurement of a newly formed crevasse splay of the Kinu River, central Japan

“…Reasons may include the low relief and urban or agricultural land uses of floodplains (Ninfo et al, 2016) and the low preservation potential of flood-related topography in urban areas (Nelson and Leclair, 2006). Moreover, in many cases, reliable topographic data before a flood event, allowing the investigation of topographic changes, are not available, which prevents detailed quantification of flood-caused topographic changes (Tamminga et al, 2015a).…”