Abstract
Abstract. r.avaflow represents an innovative open-source computational tool for routing rapid mass flows, avalanches, or process chains from a defined release area down an arbitrary topography to a deposition area. In contrast to most existing computational tools, r.avaflow (i) employs a two-phase, interacting solid and fluid mixture model (Pudasaini, 2012); (ii) is suitable for modelling more or less complex process chains and interactions; (iii) explicitly considers both entrainment and stopping with deposition, i.e. the change of the basal topography; (iv) allows for the definition of multiple release masses, and/or hydrographs; and (v) serves with built-in functionalities for validation, parameter optimization, and sensitivity analysis. r.avaflow is freely available as a raster module of the GRASS GIS software, employing the programming languages Python and C along with the statistical software R. We exemplify the functionalities of r.avaflow by means of two sets of computational experiments: (1) generic process chains consisting in bulk mass and hydrograph release into a reservoir with entrainment of the dam and impact downstream; (2) the prehistoric Acheron rock avalanche, New Zealand. The simulation results are generally plausible for (1) and, after the optimization of two key parameters, reasonably in line with the corresponding observations for (2). However, we identify some potential to enhance the analytic and numerical concepts. Further, thorough parameter studies will be necessary in order to make r.avaflow fit for reliable forward simulations of possible future mass flow events.
Highlights
Rapid flows or avalanches of snow, debris, rock, or ice, or processes, process chains, or process interactions involving more than one type of movement or material, frequently lead to loss of life, property, and infrastructures in mountainous areas worldwide
We note that the discharge and the flow height recorded by the hydrograph do not strictly follow the same pattern, as the discharge relates to a profile and the flow height relates to a point
High values of deposition indicator index (DII) are fairly constrained to those cells within the observed deposition area (ODA) which is most probably better defined than the observed impact area (OIA)
Summary
Rapid flows or avalanches of snow, debris, rock, or ice, or processes, process chains, or process interactions involving more than one type of movement or material, frequently lead to loss of life, property, and infrastructures in mountainous areas worldwide. Models attempt to identify those areas where mass flows are likely to release (landslide susceptibility; Guzzetti, 2006; Van Westen et al, 2006). Advanced fluid dynamics offer a broad array of physically based dynamic modelling approaches for mass flows, mostly referred to as granular avalanches or debris flows. Such models often centre on two-dimensional “shallow flow” equations, but they vary considerably among themselves in terms of their concept, complexity, and capacity to model specific types of phenomena. Such models often centre on two-dimensional “shallow flow” equations, but they vary considerably among themselves in terms of their concept, complexity, and capacity to model specific types of phenomena. Voellmy (1955) pioneered mass flow modelling, followed by the work of Grigoriyan et al (1967), Savage and Hutter (1989), Takahashi (1991), Iverson (1997), Published by Copernicus Publications on behalf of the European Geosciences Union
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