Debris Flow

Tamotsu Takahashi is Professor Emeritus at the University of Kyoto and at the Department of Sediment Research of the China Institute of Water Resources and Hydropower Research in Beijing. In addition to his academic positions, he is the Director of the Association for Disaster Prevention Research in Kyoto. Professor Takahashi began his career in flood dynamics research, and increasingly focused on debris flow and flood hazards. He has been honoured with several awards from the Japan Society of Civil Engineers and the Japan Society of Erosion Control Engineering. In 1991, an earlier book entitled 'Debris Flow', by Tamotsu Takahashi, in the book series of the International Association of Hydraulic Engineering and Research, was published by Balkema Publishers, now a part of the Taylor & Francis Group.

Preface





Chapter 1 What is debris flow?













Various sediment moving phenomena







Definition of debris flow







Classification and characteristics of debris flows









Stony type debris flow







Turbulent muddy type debris flow







Viscous debris flow









The significance of the mechanical classification of debris flows







Classifications on the other points of view










Chapter 2 Models for mechanics of flow







2.1 Models for solids and fluid mixture as the multi-phase flow


2.2 Single-phase continuum models


2.2.1 Visco-plastic fluid model


2.2.2 Dilatant fluid model


2.3 Two-phase continuum models (Mixture theory)


2.3.1 Stress equilibrium equations


2.3.2 Coulomb mixture theory (Quasi-static debris flows)


2.4 Theory for subaerial rapid granular flows


2.4.1 Particle collision stress


2.4.2 Kinetic stress


2.4.3 Skeletal stresses


2.4.4 Constitutive relations


2.4.5 Application of the theory to dry granular flow


2.4.6 Comparison with other constitutive relations for inertial range


2.5 Role of interstitial fluid in inertial debris flows


2.6 The mechanism of immature and turbulent muddy debris flows


2.6.1 Immature debris flow


2.6.2 Turbulent muddy debris flow


2.7 Generalized theory for inertial debris flows


2.7.1 Theoretical considerations


2.7.2 Verification by experimental data


2.7.3 Approximate solution for solids concentration and resistance to flow


2.8 Newtonian fluid model for viscous debris flow


2.8.1 Theoretical considerations


2.8.2 Verification by experiments





Chapter 3 Initiation and development of debris flow













Initiation and development of debris flow due to gully bed erosion









The formation of incipient debris flow by the effects of surface water runoff







The development of stony debris flow on sediment bed







Verification of the theory by experiments









Landslide-induced debris flow









Model for the transformation into debris flow







Mathematical model for the one-dimensional motion of an earth block







Numerical simulation of earth block and debris flow motions across three-dimensional terrain









Debris flow and flood flow induced by collapse of natural dam









Formative conditions and shapes of natural dam







Failure in entire channel width and the resulting debris flow







Prediction of debris flow/flood flow induced by the overflow in partial width












Chapter 4 Characteristics of fully developed flow













Translation of debris flow surge and the shape of the snout









The case of stony type debris flow







The case of viscous type debris flow









Boulder accumulation at the forefront of stony debris flow









Various concepts for the mechanism







The theory of Takahashi (1980)









Competence to transport large boulders







The cause of intermittency







Debris flow around bend







Routing of debris flow in the transferring reach









Kinematic wave method







Dynamic wave method












Chapter 5 Processes and geomorphology of deposition













One-dimensional stoppage/depositing processes of stony debris flow









The arrival distance at the abrupt change in channel slope







Topography of deposit formed at an abrupt slope change







Numerical simulation of depositing process









One-dimensional depositing process of turbulent muddy debris flow







Formation of debris flow fan









Description of the experimental results for stony debris flow and empirical presentations of the feature of debris flow fan







Numerical simulation of fan formation process and its verification







Numerical simulation of fan formation by turbulent debris flow









Particle size distribution in the fan formed by stony debris flow









General situations found in the field and experimental data







Mathematical model for particle size distributions









Erosion and deformation of debris flow fan









Experiments for the process of erosion







Model and its verification for the fan comprised of uniform material







Model and its verification for the fan comprised of heterogeneous material












Chapter 6 Debris flow disasters and their reproduction by computer simulations













The rain storm disasters at Okuetsu









Outline of the disaster







The natural dam formation and the damages done by backwater







Processes of destruction of the natural dam and damages downstream









Horadani debris flow disasters









Outline of the disaster







Hydrograph estimation of the debris flow







Reproduction of debris flow depositing area on the fan









Collapse of the tailings dam at Stava, Northern Italy









Outline of the disasters







Reproduction of the debris flow in the Stava River and its verification









Disasters caused by the eruption of Nevado del Ruiz Volcano









Outline of the disasters







Reproduction of the phenomena









Sediment disasters in Venezuela









Outline of the disasters







Debris flow routing under an arbitrary rainfall condition







Reproduction of debris flow hydrograph and others in the Camuri Grande River







Reproduction of sediment flooding on the Camuri Grande fan









Debris flow disasters at Atsumari, Hougawachi, Minamata City









Outline of the disasters







Reproduction of the processes of debris flow












Chapter 7 Countermeasures for debris flow disasters













Methods to prevent from debris flow generation









Hillside works







Drainage works







Groundsill and bed girdle









Debris flow control by closed type check dam









Sediment depositing process behind check (sabo) dam







Erosion process of the deposit behind sabo dam







Effects of sediment control by sabo dam to downstream









Debris flow control by open-type sabo dams









Kinds and sediment checking mechanism of open-type sabo dams







Blocking model of grid-type dam







Model for debris flow controlling by grid-type dabo dam







Determination of the optimum spacing and the optimum position to install









Making debris flow harmless by channel works and training walls









Design of countermeasures on the fan of the Camuri Grande River







Management of debris flow by training dike









Design debris flows for the countermeasure planning









Method based on the previous data







Prediction of total sediment runoff by field investigation







Theoretical prediction of debris flow scale









Debris flow prone ravines and hazardous area









Debris flow prone ravine







Hazardous zone by debris flow









Prediction of debris flow occurrence by rainfall










References





Notations





Index