9. Advances in Geofluvial Modeling: Methodologies and Applications

Stream bank erosion is an important form of channel change in alluvial environments; it should be accounted for in geomorphic studies, river restoration, dam removal, and channel maintenance projects. Recently, one-dimensional (1D) and two-dimensional (2D) flow and mobile-bed numerical models are becoming useful engineering tools for predicting channel morphological responses to stream modifications. Most, however, either ignore bank erosion or implement only simple ad hoc methods. A combined modeling of vertical and lateral fluvial processes in streams, i.e., geofluvial modeling, is important yet still at its research stage. In this chapter, advances in geofluvial modeling are presented. First, a literature review is provided in the area of geofluvial modeling. Second, important geofluvial processes are discussed as they need to be incorporated into models. Third, a recently developed 2D geofluvial model, SRH-2D, is described. SRH-2D incorporates processed-based bank erosion modules into a 2D mobile-bed module; it is developed with the primary objective of advancing the geofluvial modeling toward a practical engineering tool. Bank erosion modeling consists of a uniform retreat module and mechanistic failure module; both are suitable for uniform and multilayer banks with noncohesive or cohesive materials. The coupling techniques are developed that emphasize ease of use and model robustness (stability). Fourth and final, a number of laboratory and field cases are selected to validate and verify the geofluvial model; application cases are also presented to demonstrate the practical aspects of the model. It is found that the state-of-the-art 2D geofluvial modeling is becoming practical to assist project planning, design, and evaluation. SRH-2D can predict accurately for some streams, but only qualitatively for more complex streams.