Abstract:

Debris flow, which is usually  of high density and viscosity, is conspicuous for its composition of successive surges of various properties. A debris flow is equal to a surge sequence and thus the surge sequence is believed to convey the information about the integrated properties of a system underlying debris flow. Based on observations in Jiangjia Gully, in this paper we focus on the integrity of surge sequence by considering the autocorrelation and tempospatial interval. The Hurst exponent is employed to express the autocorrelation. Results show that the Hurst exponents are exclusively bigger than 05, the value for random series without longrun aftereffects, suggesting the longrange correlation of the surge sequences. Furthermore, an eventspace is introduced by taking each surge as a point assigned with a parameter set. Three parameters, the discharge, velocity, and time interval are chosen to define a surge point. Then a debris flow event appears as a group of points clustered in a small range in the eventspace. This visualizes the concentration of surges in temporal and spatial dimensions, and further illustrates the tempospatial correlation of the surges. The integrity and autocorrelation of the surge sequence can be taken as the sign of an underlying dynamics of debris flow.

Key words:

Key words: debris flow; surge sequence; Hurst exponent; longrange correlation