Simulation of debris flows in the Central Andes based on Open Source GIS: possibilities, limitations, and parameter sensitivity

Abstract

A GIS-based model framework, designed as a raster module for the Open Source software GRASS, was developed for simulating the mobilization and motion of debris flows triggered by rainfall. Designed for study areas up to few square kilometres, the tool combines deterministic and empirical model components for infiltration and surface runoff, detachment and sediment transport, slope stability, debris flow mobilization, and travel distance and deposition. The model framework was applied to selected study areas along the international road from Mendoza (Argentina) to Central Chile. The input parameters were investigated at the local scale. The model was run for a number of rainfall scenarios and evaluated using field observations and historical archives in combination with meteorological data. The sensitivity of the model to a set of key parameters was tested. The major scope of the paper is to highlight the capabilities of the model-and of this type of models in general-as well as its limitations and possible solutions.

Physically-based modelling of granular flows with Open Source GIS

“…(1) to (3) were solved using a high resolution Total Variation Diminishing NonOscillatory Central Differencing (TVD-NOC) Scheme, a numerical scheme useful to avoid unphysical numerical oscillations (Nessyahu and Tadmor, 1990). Cell averages of h, u and v are computed using a staggered grid: the system is moved half of the cell size with every time step, the values at the corners of the cells and in the middle of the cells are computed alternatively.…”

“…Zwinger et al (2003) adapted the Savage-Hutter model for arbitrarily shaped mountain terrain, introducing some geometric simplifications. Based on Nessyahu and Tadmor (1990) and Tai et al (2002), Wang et al (2004) devised a numerical scheme applicable to flows over complex shallow terrain along a horizontally straight flow path (Gray et al, 1999). Pudasaini and Hutter (2003) proposed an avalanche model for generally curved and twisted channels which was further developed by Pudasaini et al (2005aPudasaini et al ( , b, 2008.…”

r.randomwalk v1, a multi-functional conceptual tool for mass movement routing

“…Constrained random M. Mergili et al: r.randomwalk v1, a multi-functional conceptual tool walk approaches are used for routing mass movements such as debris flows through elevation maps (DEMs), e.g. by Gamma (2000), Wichmann and Becht (2003), Mergili et al (2012a), and Gruber and Mergili (2013). Such methods enable a certain degree of spreading of the movement by also considering other routing directions than the steepest descent.…”

“…They consider only the centre of the flowing mass, but not its deformation and the spatial distribution of the flow variables. This type of models is mainly used for snow avalanches and debris flows (Perla et al, 1980;Gamma, 2000;Wichmann and Becht, 2003;Mergili et al, 2012a;Horton et al, 2013).…”

“…Various -mostly open-source -software tools for conceptual modelling of mass movements (mainly flows) at medium or broad scales are available (e.g., Gamma, 2000;Wichmann and Becht, 2003;Mergili et al, 2012a;Horton et al, 2013). However, most of these tools lack substantial features: (i) they are limited to one single type of break criterion; (ii) they do not allow one to directly account for the uncertainty of the break criteria; (iii) they do not allow one to back calculate the statistics of a set of observed mass movements; and (iv) they do not offer built-in functionalities for evaluating the model results against observations.…”