A reduced complexity approach to morphodynamic modeling: Validation of DeltaRCM and prediction of fluviodeltaic channel dynamics

DeltaRCM is a reduced-complexity model of delta formation and evolution based on a set of simple physical rules for routing water and sediment. The hydrodynamic component of the model has been previously validated against analytical and 3D numerical modeling results and has been shown to accurately reproduce flow field features critical to delta dynamics at the level of channel processes such as backwater profile, flow around a mouth bar, flow through a single bifurcation, and flow partitioning at the network scale.

Here we focus on the morphodynamic component of DeltaRCM to: (1) identify a set of robust metrics to be used for validating morphodynamic models; (2) validate DeltaRCM results against a set of experimental and field data; and (3) investigate delta morphodynamics, especially the evolution of the channel network over time and the distribution of sand and mud in the stratigraphic record. The metrics analyzed span surface (e.g., channel density and wet fraction) and subsurface properties (e.g., sedimentograph and index of compensational stacking), as well as the system’s dynamic behavior (e.g., avulsion time scale and shoreline trajectory). These metrics are used to compare the model’s behavior to field and experimental data representing a range of boundary conditions, such as varying basin geometry, base-level cycles, and sediment input. The validation results show the range of applicability of our reduced complexity approach to modeling morphodynamics. DeltaRCM is then applied to investigate the deposition of sand and mud as a function of time and location for varying basin depth.