Channel Network Evolution Model with Subsurface Saturation Mechanism and Analysis of the Chaotic Behavior of the Model.

摘要

Hydrologists have always been interested in the geomorphologic aspects of catchments and river networks. An understanding of the relationships between basins shapes and hydrolic responses is fundamental for the purpose of hydrolic predictions, especially in ungaged basins. In the first part of this work the overload flow production mechanism used in the Willgoose-Bras-Rodriguez-Iturbe channel network and catchment evolution model was modified from the Hortonian to the subsurface saturation runoff mechanism. Two important differences were found in the behavior of the new model; one was in the evolution of the hypsometric curves of the catchment; the second was in the importance of mass movement (e.g. creep and landsliding) sediment transport in the overall behavior of the system. A new nondimensional numbers belonging to the original model. Common geomorphological statistics were measured on the simulated catchments and found to be similar to field data. the second part of this work examines the sensitivity to initial conditions present in the WBR model. Using an appropriate measure between elevation fields, the evolution of different catchments was examined. Exponential separation in phase space between trajectories of the system was found in a variety of tests. This exponential separation is the reason for the apparent randomness present in the evolution of the model. The influence of different parameters of the model on this exponential separation was also examined.