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| Titel |
Use of High Resolution LiDAR imagery for landslide identification and hazard assessment, State Highway 6, Haast Pass, New Zealand |
| VerfasserIn |
Andrew Walsh, Valerie Zimmer, David Bell |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250114599
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| Publikation (Nr.) |
 EGU/EGU2015-15390.pdf |
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| Zusammenfassung |
| This study has assessed landslide hazards associated with steep and densely vegetated bedrock slopes adjacent to State Highway 6 through the Southern Alps of New Zealand. The Haast Pass serves as one of only three routes across the Southern Alps, and is a lifeline to the southern West Coast of the South Island with a 1,000km detour required through the nearest alternative pass. Over the last 50 years the highway has been subjected to numerous landslide events that have resulted in lengthy road closures, and the death of two tourists in September 2013. To date no study has been undertaken to identify and evaluate the landslide hazards for the entire Haast Pass, with previous work focusing on post-failure monitoring or investigation of individual landslides. This study identified the distribution and extent of regolith deposits on the schist slopes, and the location and sizes of dormant and active landslides potentially impacting the highway. Until the advent of LiDAR technology it had not been possible to achieve such an evaluation because dense vegetation and very steep topography prevented traditional methods of investigation (mapping; trenching; drilling; geophysics) from being used over a large part of the area. LiDAR technology has provided the tools with which to evaluate large areas of the slopes above the highway quickly and with great accuracy. A very high resolution LiDAR survey was undertaken with a flight line overlap of 70%, resulting in six points per square metre in the raw point cloud and a post-processing point spacing of half a metre. The point cloud was transformed into a digital terrain model, and the surface interpreted using texture and morphology to identify slope materials and landslides. Analysis of the LiDAR DTM revealed that the slopes above the highway consist of variable thicknesses of regolith sourced from landsliding events, as well as large areas of bare bedrock that have not been subjected to landslides and that pose minimal hazard to the highway. The location and geometry of previously identified landslides, as well as several new landslides, have been mapped geomorphologically, and indicate that several kilometres of the pass is exposed to potentially significant landslide hazards. This study provides an example of the effectiveness of using high resolution LiDAR surveying to identify surficial deposits and landslide features in densely vegetated and steep terrain. It provides the information with which to focus investigations into the risk that theses hazards pose to the highway, as well as providing for future highway management prioritising remediation and/or protection measures. |
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