Abstract
Landslides hazard analyses entail a scale-dependent approach in order to mitigate accordingly the damages and other negative consequences at the respective scales of occurrence. Medium or large scale landslide run-out modelling for many possible landslide initiation areas has been a very difficult task in the past. This arises from the inability of the run-out models to compute the displacement with a large amount of individual initiation areas as it turns out to be computationally strenuous. Most of the existing physically based run-out models have difficulties in handling such situations. For this reason, empirical methods have been used as a practical mean to predict landslides mobility at a medium scale (1: 10,000 to 1: 50,000). They are the most widely used techniques to estimate the maximum run-out distance and affected zones not only locally but also regionally. In this context, a medium scale numerical model for flow-like mass movements in urban and mountainous areas was developed. “AschFlow” is 2-D one-phase continuum model that simulates, the entrainment, spreading and deposition process of a landslide or debris flow at a medium scale. The flow is thus treated as a single phase material, whose behavior is controlled by rheology (e.g., Voellmy or Bingham). The model has been developed and implemented in a dynamic GIS environment. The deterministic nature of the approach makes it possible to calculate the velocity, height and increase in mass by erosion, resulting in the estimation of various forms of impacts exerted by debris flows at the medium scale. The developed regional model “AschFlow” was applied and evaluated in well documented areas with known past debris flow events. The “AschFlow” model outputs can be considered as an indication of areas possibly affected with a defined intensity for one or more landslide events. From a user perspective the “AschFlow” model can be seen as a standalone model which can be utilized for a first assessment of potentially impact areas.
Highlights
Landslides hazard analyses entail a scale-dependent approach in order to mitigate the damages and other negative consequences at the respective scales of occurrence
The empirical equations are implemented in a geographical information system (GIS)-based simulation program and combined with a simple flow routing algorithm, to determine the potential run-out area covered by debris flow deposits
“AschFlow” is based on an infinite slope model without any lateral or active-passive forces assuming that the forces are hydrostatic
Summary
Landslides hazard analyses entail a scale-dependent approach in order to mitigate the damages and other negative consequences at the respective scales of occurrence. Most of the existing physically based run-out models have difficulties in handling such situations For this reason, empirical methods have been used as a practical mean to predict landslides mobility at a medium scale (1: 10,000 to 1: 50,000). Empirical methods have been used as a practical mean to predict landslides mobility at a medium scale (1: 10,000 to 1: 50,000) They are the most widely used techniques to estimate the maximum run-out distance and affected zones locally and regionally. The goal of a medium scale analysis is to identify all the potentially unstable areas as accurate as possible and the down-slope regions probably affected by the flow of the failed material This analysis should be used as a first assessment for the potential impact zones and to give an indication where further local studies should be carried out with more detail (van Westen et al 2006). The AschFlow model was Literature review The main approaches that have been carried out in the past for a medium scale hazard analysis of landslides and debris flows can be divided by: − methods using empirical approaches, − methods using flow routing models; and - method using dynamic run-out models.
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