ABSTRACT:

Debris flow caused by the landside is one of complicated geologic hazards in mountain area, which is closely associated with geology, lithology, the mechanical characteristics of the rock and soil, rainfall, groundwater and land usage condition etc. The analysis of immanent relationships between landslide and Debris flow can not only provide some important information about landslide failure mechanism, but also be used as the basis of evaluation of Debris flow triggered by landslides. In this paper, the depth integral was applied in two-dimensional mathematical model of Debris flow which is based on the principle of conservation of mass and viscous Newtonian fluid Navier-Stovkes equation. Then, this equation was numerically computed by using the finite difference method. The relational expression between streams tilt angle and the width of affected range of Debris flow, which is obtained from statistics, was applied to analyse the possibility of Debris flow induced by landslides which once failed under the similar geological conditions. Combining with GIS, the model can also be used to predict impacted range of Debris flow by using risk map to show the zones that may be affected by the Debris flow.

1 INTRODUCTION

Majority Debris flows usually happen after the occurrence along stem from the landside by the rainfall. They are results of the area of the landslides advanced to valley. The debris flows have the characteristics of sudden eruption, intermittent and enormous energy. Because of the destructive power, the debris flow may cause heavy casualties and serious economic losses. Therefore, the prediction of disaster area and motion trajectory has already become one of the most important the risk assessment. Geographic information system and digital model has become a practical and effective means in analyzing geologic hazard. These two techniques have strong treatment ability of spatial data and the attribute data, and can also be efficiently solved in data collecting, data processing, and data analysis about landslide and debris flow. By the method of the interaction between sensitivity factor of spatial distribution and digital model to assess to the hazard of the debris flow gully become hot spot.

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