Book Description

Debris flows are a potentially catastrophic geological hazard worldwide destroying lives, properties, and infrastructure. It is characterized as one of the most destructive among different types of landslide phenomena. They are gravity-driven mass flows involving multiple interacting phases in contact with the environment and with each other during its propagation. The wide range of material sizes ranging from clay to huge boulders with varying compositions poses significant modeling challenges. Lack of monitoring stations, event data, and effective physical models renders it necessary to employ numerical simulations to study the process of the debris flows and predict possibilities for potential hazards. The present study explores a recently developed multi-phase model, implemented in a novel computation tool r.avaflow for simulation of complex multi-phase flows. The present study aims to understand the difference in flow characteristics of different types of mass flows, which vary in material type and composition. First, a numerical simulation of debris flow, mudflows, earth flow, and complex flows, on an idealized slope is conducted to analyze the differences in their flow behavior in the form of run-out distance, velocity, the height of flow, peak discharge, final deposition, kinetic energy, and flow pressure, etc. The results demonstrate the high destructive potential of different types of flows and can be utilized for the delineation of hazard-prone areas. Subsequently, two case studies of well-documented debris flow events in active debris flow sites are also carried out. The first case study focuses on a debris flow event of August 2009 in Tyrol, Austria, and the second case study investigates a debris flow incident of the Chalk Cliff region in Colorado, USA. These studies allow extensive utilization of the important features of numerical simulations in actual landscapes. The case studies are validated using available event data and show reasonably good accuracy. The physical characteristics of the debris flow of case studies are further analyzed. Parametric studies are performed to investigate the effect of various parameters on the flow behavior. An important phenomenon of the entrainment of the material, a major reason for many catastrophic debris flows, is numerically simulated, and the results show how a small event could turn into a massive event by the erosion of basal material. Sensitivity analysis shows the variation of simulation results with the aid of various statistical performance scores. The study will help to understand and differentiate the behavior of various flows. It may also eventually assist in developing effective hazard assessment and mitigation strategies with reliable quantitative modeling of potential future flow events.