1Department of Civil, Environmental, and Geo-Engineering, National Center for Earth Surface Dynamics, Saint Anthony Falls Laboratory, University of Minnesota, Twin Cities, Minneapolis, Minnesota, USA
2Department of Geology and Geophysics, National Center for Earth Surface Dynamics, Saint Anthony Falls Laboratory, University of Minnesota, Twin Cities, Minneapolis, Minnesota, USA
*now at: Department of Civil, Architectural and Environmental Engineering and Center for Research in Water Resources, The University of Texas at Austin, Austin, Texas, USA
Received: 25 Jun 2014 – Discussion started: 28 Jul 2014
Abstract. In this work we develop a reduced-complexity model (RCM) for river delta formation (referred to as DeltaRCM in the following). It is a rule-based cellular morphodynamic model, in contrast to reductionist models based on detailed computational fluid dynamics. The basic framework of this model (DeltaRCM) consists of stochastic parcel-based cellular routing schemes for water and sediment and a set of phenomenological rules for sediment deposition and erosion. The outputs of the model include a depth-averaged flow field, water surface elevation and bed topography that evolve in time. Results show that DeltaRCM is able (1) to resolve a wide range of channel dynamics – including elongation, bifurcation, avulsion and migration – and (2) to produce a variety of deltas such as alluvial fan deltas and deltas with multiple orders of bifurcations. We also demonstrate a simple stratigraphy recording component which tracks the distribution of coarse and fine materials and the age of the deposits. Essential processes that must be included in reduced-complexity delta models include a depth-averaged flow field that guides sediment transport a nontrivial water surface profile that accounts for backwater effects at least in the main channels, both bedload and suspended sediment transport, and topographic steering of sediment transport.
Revised: 31 Dec 2014 – Accepted: 08 Jan 2015 – Published: 28 Jan 2015
Liang, M., Voller, V. R., and Paola, C.: A reduced-complexity model for river delta formation – Part 1: Modeling deltas with channel dynamics, Earth Surf. Dynam., 3, 67-86, doi:10.5194/esurf-3-67-2015, 2015.