Numerical modeling and simulation for sediment routing systems

Earth‘s landscape is a dynamic surface shaped by the interplay between tectonics and climate-mediated surface processes related to erosion, sediment transport and deposition. Sediment is moved in flowing surface water from the erosional engine in mountainous regions to its eventual deposition in basins by the sediment routing system. The last decades has seen considerable work on trying to understand different aspects of the sediment routing system using numerical surface process models. Though such models have been successful in their ability to generate realistic looking topography, they lack predictive power as they are based on oversimplified physics, particularly concerning overland fluid flow and because their parameters are poorly constrained.

The thesis is intended to couple the existing physically based models for erosion, sediment transport and depostion to fully dynamic surface water flow model to address two main aspects of the sediment routing system. The first is the problem of channel initiation and formation of mature drainage basins, the second is the problem of controls on the morphology and dynamics of alluvial rivers. One major obstacle in devising realistic numerical models for alluvial systems is the unconformity of the time scales between the coupled processes of fluid dynamics of the overland water flow and the erosion/depsition of the sediments. The time scale involved in evolution of the sedimental systems is millions of years whereas the flow dynamics of water is comparatively very fast process.

The problem of the significant time scale difference can be solved either by utilizing efficient numerical schemes supported by high performance computing to cope with huge amount of computations required for accurate solution of the model or by simplifying the models and their coupling which can significantly reduce the amount of required computations. The objective of the research is to find the optimal balance of the two approaches so that a realistic model capable of predicting behavior of the system can be developed which would also help in better understanding of the alluvial systems.