GIS-based numerical modelling of debris flow motion across three-dimensional terrain

Abstract

Abstract:The objective of this study is to incorporate a numerical model with GIS to simulate the movement, erosion and deposition of debris flow across the three dimensional complex terrain. In light of the importance of erosion and deposition processes during debris flow movement, no entrainment assumption is unreasonable. The numerical model considering these processes is used for simulating debris flow. Raster grid networks of a digital elevation model in GIS provide a uniform grid system to describe complex topography. As the raster grid can be used as the finite difference mesh, the numerical model is solved numerically using the Leap-frog finite difference method. Finally, the simulation results can be displayed by GIS easily and used to debris flow evaluation. To illustrate this approach, the proposed methodology is applied to the Yohutagawa debris flow that occurred on 20th October 2010, in AmamiOshima area, Japan. The simulation results that reproduced the movement, erosion and deposition are in good agreement with the field investigation. The effectiveness of the dam in this real-case is also verified by this approach. Comparison with the results were simulated by other models, shows that the present coupled model is more rational and effective.

Predictive Simulation of Concurrent Debris Flow: How Slope Failure Locations Affect Predicted Damage

“…To treat debris flow, we selected a two-dimensional simulation model based on the dilatant fluid model developed by Takahashi (2007), which has been frequently applied in practice (Wu et al, 2013;Nakatani et al, 2016). The governing equations can be written as ,…”

Assessing entrainment of bed material in a debris‐flow event: a theoretical approach incorporating Monte Carlo method

“…Previous precipitation in the terrain before the event is beneficial to understand the accumulated rainfall, which could be used to estimate the critical volume concentration c * of the initial landslide triggering debris flow (Takahashi, 1991). We speculated that the initial c * of the 2010 Yohutagawa debris-flow event was 0.44 (Wu et al 2013), which implied that the ρ d g should be 17.4 kN m À3 .…”

“…Attempts have been made to incorporate entrainment processes in these models to simulate the propagation of debris flow over erodible beds (e.g. McDougall and Hungr, 2005;Chen et al, 2006;Mangeney et al, 2007;Crosta et al, 2009aCrosta et al, , 2009bChristen et al, 2010;de Blasio et al, 2011;Pirulli and Pastor 2012;Wu et al, 2013;Han et al, 2015a). However, given that very few observations are available to constrain the models, a better theoretical understanding of entrainment processes still remains a major issue and would be instrumental to improving simulation results.…”

Numerical Simulation of a Debris Flow on the Basis of a Two-Dimensional Continuum Body Model

“…When the unstable sediment and snow cover on the base rock is thin and the land slope is mild, the entrainment can be neglected (e.g., [15][16][17]). However, when the unstable sediment and snow cover on the base rock is thick and the land slope is steep, the entrainment should be considered.Some studies (e.g., [4,18,19]) have used the idea that the thickness of the bed surface layer where the bed shear stress is larger than the bed resistance is erosion depth, and many bed erosion rate equations are proposed (e.g., [10,13,[20][21][22][23]). These models can calculate the suitable bed erosion rate using suitable parameters.…”

“…Some studies (e.g., [4,18,19]) have used the idea that the thickness of the bed surface layer where the bed shear stress is larger than the bed resistance is erosion depth, and many bed erosion rate equations are proposed (e.g., [10,13,[20][21][22][23]). These models can calculate the suitable bed erosion rate using suitable parameters.…”