Debris flow hazard assessment for kunanyi / Mt. Wellington
MRT has released a new debris flow hazard assessment for kunanyi/Mt. Wellington. The assessment documents the evidence for, and methods used in, the creation of a new generation of debris flow maps for the Hobart area.
Debris flows, such as a large event originating on the slopes of Mt. Arthur and affecting areas down to the Derwent shoreline in 1872, pose a significant threat to communities situated in their potential runout zones. In order to identify these areas, MRT produced the first debris flow susceptibility maps for Hobart and Glenorchy in 2004.
In response to the release of the 2004 mapping, a validation study was commissioned by Hobart Water (now part of TasWater) using the services of specialist landslide consultants, with the assistance of MRT. The review, which was completed in 2007, recommended further work be undertaken to improve calibration of the regional debris flow database with the source area characteristics.
Since the release of MRT's original debris flow maps, and the 2007 review, tools for modelling debris flows have improved and new datasets, such as regional orthophoto imagery and high resolution digital elevation models (DEM) derived from LiDAR (Light Detection and Ranging imagery), have become available. The authors of this new study have taken the following approach:
- Review and refine the qualitative understanding of geological and geomorphic processes on the mountain;
- Collect and analyse information on past debris flows occurring both within the study area;
- Compare characteristics of the recorded events with those recorded in the international literature;
- Determine areas of regional and local debris flow susceptibility and calculate quantitative geomorphic process rates;
- Undertake predictive runout modelling for each of the principal catchments in the study area.
Download a copy of the report (with links to new debris flow mapping) here.