River delta floodplains: diffusive deposition, crevasse splays, or avulsions?

River deltas and their floodplains constitute a major component of Earth's sedimentary record and its petroleum reserves. In deltas, the interaction between a deltaic channel and its floodplain is highly heterogeneous and can result in diffusive deposition, crevasse splays, but also river avulsions. Formative conditions are not well understood, yet they carry important implications for the timescales, length scales, and morphologies of deltaic sedimentary bodies. Here we use Delft3D to investigate channel-floodplain interactions, and simulate responses from crevasse splays to avulsions including the effects of vegetation and soil consolidation. Model simulations show that crevasse splays heal because floodplain aggradation reduces the water surface slope, decreasing water discharge into the flood basin. Easily erodible and unvegetated floodplains increase the likelihood for channel avulsions. Denser vegetation and less potential for soil consolidation results in small crevasse splays that are efficient sediment traps but that are also short-lived.