Field testing innovative differential geospatial and photogrammetric monitoring technologies in mountainous terrain near Ashcroft, British Columbia, Canada

Abstract

This paper presents a novel approach to continuously monitor very slow-moving translational landslides in mountainous terrain using conventional and experimental differential global navigation satellite system (d-GNSS) technologies. A key research question addressed is whether displacement trends captured by a radio-frequency "mobile" d-GNSS network compare with the spatial and temporal patterns in activity indicated by satellite interferometric synthetic aperture radar (InSAR) and unmanned aerial vehicle (UAV) photogrammetry. Field testing undertaken at Ripley Landslide, near Ashcroft in south-central British Columbia, Canada, demonstrates the applicability of new geospatial technologies to monitoring ground control points (GCPs) and railway infrastructure on a landslide with small and slow annual displacements (<10 cm/yr). Each technique records increased landslide activity and ground displacement in late winter and early spring. During this interval, river and groundwater levels are at their lowest levels, while ground saturation rapidly increases in response to the thawing of surficial earth materials, and the infiltration of snowmelt and runoff occurs by way of deep-penetrating tension cracks at the head scarp and across the main slide body. Research over the last decade provides vital information for government agencies, national railway companies, and other stakeholders to understand geohazard risk, predict landslide movement, improve the safety, security, and resilience of Canada's transportation infrastructure; and reduce risks to the economy, environment, natural resources, and public safety.

Benchmarked RADARSAT-2, SENTINEL-1 and RADARSAT Constellation Mission Change-Detection Monitoring at North Slide, Thompson River Valley, British Columbia: ensuring a Landslide-Resilient National Railway Network

“…Geocoding digital elevation models from LiDAR, bathymetry, UAV and RTK-GNSS surveys Rigorous change-detection monitoring requires an accurate and precise elevation model to serve as a reference base map (Huntley et al 2021a). InSAR processing and landslide change-detection and benefits from an accurate high-resolution digital elevation model (DEM) to simulate and remove the topographic effects from the interferograms (cf.…”

“…In March 2015, a single-beam acoustic bathymetric survey of Thompson River was undertaken between Ashcroft and the Basque Slide (Huntley et al 2019a(Huntley et al , 2021a; Figure 1b). Extreme weather conditions and very low river levels produced operational safety concerns, limiting jet boat operation to the thalweg (i.e., the longitudinal path of greatest depth down the channel).…”

“…To provide high-precision data, jet boat speed was maintained to 14-11 (11) 06-01 to 23-02, 08-12 (4) 2015 07-04 to 09-11 (9) 01-01 to 14-03, 03-12 to 27-12 (6) 2015 10-03 to 01-11 (14) 17-01 to 29-01, 25-11 to 19-12 (4) 2015 27-03 to 10-11 (20) 14-01 to 07-02, 04-12 to 28-12 (4 between 5 km h À1 and 8 km h À1 . The RTK-GNSS rover was also used to measure water surface, wetted width, and bank elevations up to the high-water mark at channel gradient changes (e.g., upstream and downstream ends of rapids where data quality was poor or absent), and where bathymetric surveying coverage was acceptable (Figure 5b; Huntley et al 2021a).…”

“…UAV survey flight planning was conducted using Map Pilot (2019 and 2020). Plan-view color aerial photographs were merged using SfM software to generate a 2 cm-resolution DSM (Huntley et al 2021a).…”

“…Satellite-based C-band synthetic aperture radar (SAR) has been widely and successfully applied to monitor landslide deformation at local and regional scales in many parts of the world (e.g., Barrett et al 2012; Cascini et al 2010;Hu et al 2019;Mateos et al 2017;Michoud et al 2016;Necsoiu et al 2014;Novellino et al 2017;Tanteri et al 2016). Recent studies in the Thompson River valley have demonstrated the effectiveness of persistent coherent target and differential interferometric techniques applied to RADARSAT 2 (RS2) C-band SAR imagery to delimit unstable terrain, back-analyse slope displacement velocities, and derive long-term displacement trends (e.g., Huntley et al 2017Huntley et al , 2021aJournault et al 2016Journault et al , 2018. This technical note builds upon, and extends earlier research efforts in the transportation corridor.…”