Author(s): Chris Paola

Linked Author(s): Chris Paola

Keywords: No Keywords

Abstract: An "autocycle" is a cycle or fluctuation that is produced by internal processes within a transport system, in the absence of external forcing. Here we investigate the characteristics of autocyclic flucutations produced in two highly simplified but representative sediment-transport systems: (1) a two-dimensional cellular model of a braided stream; and (2) a directional variant of the original "sand-pile" system developed for the study of self-organized criticality (SOC), but with the addition of sediment input at the upstream end. Both models produce fluctuations in local sediment flux and rate of deposition entirely through their internal dynamics. The fluctuations are typically broadband and do not have any preferred cycle period. When external cycles are imposed occur on time scales that are much longer than those of the longest autocycles the autocycles appear as superimposed noise. However, when allocyclic forcing is imposed within the bandwidth of the internally generated fluctuations, the external signal can be lost. This is not a "masking" effect (i.e. a linear superposition of the autocylic and allocyclic signals); rather, the nonlinearity of the processes that generate the fluctuations causes the external signal to be destroyed as it propagates through the system.

DOI:

Year: 1997