Multiscale analysis of surface roughness for the improvement of natural hazard modelling

<p>Surface roughness influences the release of avalanches and the dynamics of rockfall, avalanches and debris flow, but it is often not objectively implemented in natural hazard modelling. For two study areas, a treeline ecotone and a windthrow-disturbed forest landscape of the European Alps,...

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Autores principales: N. Brožová, T. Baggio, V. D'Agostino, Y. Bühler, P. Bebi
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Publicado: Copernicus Publications 2021
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spelling oai:doaj.org-article:d7f6a0f17468408687bea4aa796d8d862021-11-22T13:31:00ZMultiscale analysis of surface roughness for the improvement of natural hazard modelling10.5194/nhess-21-3539-20211561-86331684-9981https://doaj.org/article/d7f6a0f17468408687bea4aa796d8d862021-11-01T00:00:00Zhttps://nhess.copernicus.org/articles/21/3539/2021/nhess-21-3539-2021.pdfhttps://doaj.org/toc/1561-8633https://doaj.org/toc/1684-9981<p>Surface roughness influences the release of avalanches and the dynamics of rockfall, avalanches and debris flow, but it is often not objectively implemented in natural hazard modelling. For two study areas, a treeline ecotone and a windthrow-disturbed forest landscape of the European Alps, we tested seven roughness algorithms using a photogrammetric digital surface model (DSM) with different resolutions (0.1, 0.5 and 1 m) and different moving-window areas (9, 25 and 49 m<span class="inline-formula"><sup>2</sup></span>). The <i>vector ruggedness measure</i> roughness algorithm performed best overall in distinguishing between roughness categories relevant for natural hazard modelling (including shrub forest, high forest, windthrow, snow and rocky land cover). The results with 1 m resolution were found to be suitable to distinguish between the roughness categories of interest, and the performance did not increase with higher resolution. In order to improve the roughness calculation along the hazard flow direction, we tested a directional roughness approach that improved the reliability of the surface roughness computation in channelised paths. We simulated avalanches on different elevation models (lidar-based) to observe a potential influence of a DSM and a digital terrain model (DTM) using the simulation tool Rapid Mass Movement Simulation (RAMMS). In this way, we accounted for the surface roughness based on a DSM instead of a DTM, which resulted in shorter simulated avalanche runouts by 16 %–27 % in the two study areas. Surface roughness above a treeline, which in comparison to the forest is not represented within the RAMMS, is therefore underestimated. We conclude that using DSM-based surface roughness in combination with DTM-based surface roughness and considering the directional roughness is promising for achieving better assessment of terrain in an alpine landscape, which might improve the natural hazard modelling.</p>N. BrožováN. BrožováN. BrožováT. BaggioV. D'AgostinoY. BühlerY. BühlerP. BebiP. BebiCopernicus PublicationsarticleEnvironmental technology. Sanitary engineeringTD1-1066Geography. Anthropology. RecreationGEnvironmental sciencesGE1-350GeologyQE1-996.5ENNatural Hazards and Earth System Sciences, Vol 21, Pp 3539-3562 (2021)
institution DOAJ
collection DOAJ
language EN
topic Environmental technology. Sanitary engineering
TD1-1066
Geography. Anthropology. Recreation
G
Environmental sciences
GE1-350
Geology
QE1-996.5
spellingShingle Environmental technology. Sanitary engineering
TD1-1066
Geography. Anthropology. Recreation
G
Environmental sciences
GE1-350
Geology
QE1-996.5
N. Brožová
N. Brožová
N. Brožová
T. Baggio
V. D'Agostino
Y. Bühler
Y. Bühler
P. Bebi
P. Bebi
Multiscale analysis of surface roughness for the improvement of natural hazard modelling
description <p>Surface roughness influences the release of avalanches and the dynamics of rockfall, avalanches and debris flow, but it is often not objectively implemented in natural hazard modelling. For two study areas, a treeline ecotone and a windthrow-disturbed forest landscape of the European Alps, we tested seven roughness algorithms using a photogrammetric digital surface model (DSM) with different resolutions (0.1, 0.5 and 1 m) and different moving-window areas (9, 25 and 49 m<span class="inline-formula"><sup>2</sup></span>). The <i>vector ruggedness measure</i> roughness algorithm performed best overall in distinguishing between roughness categories relevant for natural hazard modelling (including shrub forest, high forest, windthrow, snow and rocky land cover). The results with 1 m resolution were found to be suitable to distinguish between the roughness categories of interest, and the performance did not increase with higher resolution. In order to improve the roughness calculation along the hazard flow direction, we tested a directional roughness approach that improved the reliability of the surface roughness computation in channelised paths. We simulated avalanches on different elevation models (lidar-based) to observe a potential influence of a DSM and a digital terrain model (DTM) using the simulation tool Rapid Mass Movement Simulation (RAMMS). In this way, we accounted for the surface roughness based on a DSM instead of a DTM, which resulted in shorter simulated avalanche runouts by 16 %–27 % in the two study areas. Surface roughness above a treeline, which in comparison to the forest is not represented within the RAMMS, is therefore underestimated. We conclude that using DSM-based surface roughness in combination with DTM-based surface roughness and considering the directional roughness is promising for achieving better assessment of terrain in an alpine landscape, which might improve the natural hazard modelling.</p>
format article
author N. Brožová
N. Brožová
N. Brožová
T. Baggio
V. D'Agostino
Y. Bühler
Y. Bühler
P. Bebi
P. Bebi
author_facet N. Brožová
N. Brožová
N. Brožová
T. Baggio
V. D'Agostino
Y. Bühler
Y. Bühler
P. Bebi
P. Bebi
author_sort N. Brožová
title Multiscale analysis of surface roughness for the improvement of natural hazard modelling
title_short Multiscale analysis of surface roughness for the improvement of natural hazard modelling
title_full Multiscale analysis of surface roughness for the improvement of natural hazard modelling
title_fullStr Multiscale analysis of surface roughness for the improvement of natural hazard modelling
title_full_unstemmed Multiscale analysis of surface roughness for the improvement of natural hazard modelling
title_sort multiscale analysis of surface roughness for the improvement of natural hazard modelling
publisher Copernicus Publications
publishDate 2021
url https://doaj.org/article/d7f6a0f17468408687bea4aa796d8d86
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