Quantitative Rockfall Hazard Assessment of the Norwegian Road Network and Residences at an Indicative Level from Simulated Trajectories

Field observations provide valuable information for rockfall assessments, but estimating physical and statistical quantities related to rockfall propagation directly is challenging. Simulations are commonly used to infer these quantities, but their subjectivity can result in varying hazard land use...

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Main Authors: François Noël, Synnøve Flugekvam Nordang
Format: Article
Language:English
Published: MDPI AG 2025-02-01
Series:Remote Sensing
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Online Access:https://www.mdpi.com/2072-4292/17/5/819
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author François Noël
Synnøve Flugekvam Nordang
author_facet François Noël
Synnøve Flugekvam Nordang
author_sort François Noël
collection DOAJ
description Field observations provide valuable information for rockfall assessments, but estimating physical and statistical quantities related to rockfall propagation directly is challenging. Simulations are commonly used to infer these quantities, but their subjectivity can result in varying hazard land use zonation extents for different projects. This paper focuses on the application of simulated trajectories for rockfall hazard assessments, with an emphasis on reducing subjectivity. A quantitative guiding rockfall hazard methodology based on earlier concepts is presented and put in the context of legislated requirements. It details how the temporal hazard component, related to the likelihood of failure, can be distributed spatially using simulated trajectories. The method can be applied with results from any process-based software and combined with various prediction methods of the temporal aspect, although this aspect is not the primary focus. Applied examples for static objects and moving objects, such as houses and vehicles, are shown to illustrate the important effect of the object size. For that purpose, the methodology was applied at an indicative level over Norway utilizing its 1 m detailed digital terrain model (DTM) acquired from airborne LiDAR. Potential rockfall sources were distributed in 3D where slopes are steeper than 50°, as most rockfall events in the national landslide database (NSDB) occurred in such areas. This threshold considerably shifts toward gentler slopes when repeating the analysis with coarser DTMs. Simulated trajectories were produced with an adapted version of the simulation model stnParabel. Comparing the number of trajectories reaching the road network to the numerous related registered rockfall events of the NSDB, an indicative averaged yearly frequency of released rock fragments of 1/25 per 10,000 m<sup>2</sup> of cliff was obtained for Norway. This average frequency can serve as a starting point for hazard assessments and should be adjusted to better match local conditions.
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spelling doaj-art-477b24bced2e4ebba7243012155f71662025-08-20T02:59:15ZengMDPI AGRemote Sensing2072-42922025-02-0117581910.3390/rs17050819Quantitative Rockfall Hazard Assessment of the Norwegian Road Network and Residences at an Indicative Level from Simulated TrajectoriesFrançois Noël0Synnøve Flugekvam Nordang1Risk Analysis Group, Institute of Earth Sciences, University of Lausanne, 1015 Lausanne, SwitzerlandMitigations Section, The Norwegian Water Resources and Energy Directorate, 7030 Trondheim, NorwayField observations provide valuable information for rockfall assessments, but estimating physical and statistical quantities related to rockfall propagation directly is challenging. Simulations are commonly used to infer these quantities, but their subjectivity can result in varying hazard land use zonation extents for different projects. This paper focuses on the application of simulated trajectories for rockfall hazard assessments, with an emphasis on reducing subjectivity. A quantitative guiding rockfall hazard methodology based on earlier concepts is presented and put in the context of legislated requirements. It details how the temporal hazard component, related to the likelihood of failure, can be distributed spatially using simulated trajectories. The method can be applied with results from any process-based software and combined with various prediction methods of the temporal aspect, although this aspect is not the primary focus. Applied examples for static objects and moving objects, such as houses and vehicles, are shown to illustrate the important effect of the object size. For that purpose, the methodology was applied at an indicative level over Norway utilizing its 1 m detailed digital terrain model (DTM) acquired from airborne LiDAR. Potential rockfall sources were distributed in 3D where slopes are steeper than 50°, as most rockfall events in the national landslide database (NSDB) occurred in such areas. This threshold considerably shifts toward gentler slopes when repeating the analysis with coarser DTMs. Simulated trajectories were produced with an adapted version of the simulation model stnParabel. Comparing the number of trajectories reaching the road network to the numerous related registered rockfall events of the NSDB, an indicative averaged yearly frequency of released rock fragments of 1/25 per 10,000 m<sup>2</sup> of cliff was obtained for Norway. This average frequency can serve as a starting point for hazard assessments and should be adjusted to better match local conditions.https://www.mdpi.com/2072-4292/17/5/819rockfallsimulationvalidationsusceptibilityhazardrisk
spellingShingle François Noël
Synnøve Flugekvam Nordang
Quantitative Rockfall Hazard Assessment of the Norwegian Road Network and Residences at an Indicative Level from Simulated Trajectories
Remote Sensing
rockfall
simulation
validation
susceptibility
hazard
risk
title Quantitative Rockfall Hazard Assessment of the Norwegian Road Network and Residences at an Indicative Level from Simulated Trajectories
title_full Quantitative Rockfall Hazard Assessment of the Norwegian Road Network and Residences at an Indicative Level from Simulated Trajectories
title_fullStr Quantitative Rockfall Hazard Assessment of the Norwegian Road Network and Residences at an Indicative Level from Simulated Trajectories
title_full_unstemmed Quantitative Rockfall Hazard Assessment of the Norwegian Road Network and Residences at an Indicative Level from Simulated Trajectories
title_short Quantitative Rockfall Hazard Assessment of the Norwegian Road Network and Residences at an Indicative Level from Simulated Trajectories
title_sort quantitative rockfall hazard assessment of the norwegian road network and residences at an indicative level from simulated trajectories
topic rockfall
simulation
validation
susceptibility
hazard
risk
url https://www.mdpi.com/2072-4292/17/5/819
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