Combination of UAV and terrestrial photogrammetry to assess rapid glacier evolution and map glacier hazards

Abstract

Abstract. Tourists and hikers visiting glaciers all year round face hazards such as sudden terminus collapses, typical of such a dynamically evolving environment. In this study, we analyzed the potential of different survey techniques to analyze hazards of the Forni Glacier, an important geosite located in Stelvio Park (Italian Alps). We carried out surveys in the 2016 ablation season and compared point clouds generated from an unmanned aerial vehicle (UAV) survey, closerange photogrammetry and terrestrial laser scanning (TLS). To investigate the evolution of glacier hazards and evaluate the glacier thinning rate, we also used UAV data collected in 2014 and a digital elevation model (DEM) created from an aerial photogrammetric survey of 2007. We found that the integration between terrestrial and UAV photogrammetry is ideal for mapping hazards related to the glacier collapse, while TLS is affected by occlusions and is logistically complex in glacial terrain. Photogrammetric techniques can therefore replace TLS for glacier studies and UAV-based DEMs hold potential for becoming a standard tool in the investigation of glacier thickness changes. Based on our data sets, an increase in the size of collapses was found over the study period, and the glacier thinning rates went from 4.55 ± 0.24 m a −1 between 2007 and 2014 to 5.20 ± 1.11 m a −1 between 2014 and 2016.

Glacier Facies Mapping Using a Machine-Learning Algorithm: The Parlung Zangbo Basin Case Study

“…Due to the laborious work of manual delineation, many researchers have further proposed semi-automated methods to extract the debris-covered glacial surface [13,14]. The use of Unmanned Aerial Vehicles (UAVs) and terrestrial remote sensing techniques offers new ways to monitor the debris-covered glaciers on a detailed spatial scale [15,16].Nevertheless, the spatial heterogeneity of the glacier surface still hampers the identification of glaciers and increases the difficulty of observing and understanding glacier changes. Automated mapping of glaciers based on remotely sensed multispectral data is often hindered by orographic clouds, highly variable snow conditions, and the spectral similarity of supraglacial debris with the adjacent bedrock [6].…”

“…Due to the laborious work of manual delineation, many researchers have further proposed semi-automated methods to extract the debris-covered glacial surface [13,14]. The use of Unmanned Aerial Vehicles (UAVs) and terrestrial remote sensing techniques offers new ways to monitor the debris-covered glaciers on a detailed spatial scale [15,16].…”

Monitoring Alpine Glaciers From Close-Range to Satellite Sensors

“…In Scaioni et al (2018) the use of SfM to reconstruct Alpine glaciers is addressed and some technical considerations reported. As discussed in Fugazza et al (2018), the integration of images collected from ground-based station and images acquired from a drone is demonstrated to be a more complete way to describe the topography of an Alpine glacier.…”

“…On the other hand, raw images to process or final products such as digital elevation models (DEMs) and orthoimages may be retrieved from regional projects. Though the image resolution is typically lower than in the case of close/near sensing campaigns, aerial photos may help compute the global volume of a glacier to be compared within different measurement epochs, if available (see Fugazza et al, 2018).…”

“…In recent years the Forni Glacier (Ortles Cevedale group, Rhaetian Alps) located in the National Stelvio Park (Italy) has been deeply investigated using remote-sensing techniques (see Fugazza et al, 2018;Scaioni et al, 2018;Fugazza, 2019). These analyses have continued a series of observations recorded during previous decades when a progressive thinning has happened (Diolaiuti and Smiraglia, 2010).…”