Debris flow runout simulation based on empirical and continuum modelling approaches

Arghya, Arijit Biswas (2024) Debris flow runout simulation based on empirical and continuum modelling approaches. Masters thesis, Memorial University of Newfoundland.

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Abstract

Debris flow is an extremely rapid flow type of landslide that consists of a mixture of materials, including soil, mud, rock, and water, which flows down a slope. A debris flow might be initiated due to rapid rainfall, logging, snowmelt, or sudden changes in the landscape. It has a relatively higher potential to cause loss of lives and damage to the infrastructure due to its higher velocity, huge impact force, and longer runout. Therefore, predicting the extent and impacts of debris flow is important. Several computer programs are available for simulating debris flows. These programs have been developed based on some simplified models due to the challenges of encompassing the complexities of the mechanisms of such a large event. This study uses three simulation tools— DebrisFlow Predictor, Flow-R, and RAMMS—to simulate actual debris flow events at three different sites. Each site is characterized by unique features. (e.g., channelized/unchannelized, granular/muddy flow, topography, soil type, etc.). The underlying features (e.g., displacement of debris) of each program are also different. By comparing the simulation results with satellite images, it is shown that all three numerical programs can simulate the debris flows if appropriate model parameters are selected. The erosion of the channel bed during downslope displacement of debris can significantly affect simulation results. RAMMS has the capability of simulating the erosion effects if the erosion properties and erosion zone are defined properly. Defining the erosion zone without having post-event data is challenging. Therefore, the authors suggest using DebrisFlow Predictor, which can be used to identify the zones of erosion and deposition based on statistical approaches. Flow-R can be advantageous for preliminary assessments of runout extent over a large area which is based on fewer input parameters and limited information about the initiation of debris flow.

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