When Does Faulting-Induced Subsidence Drive Distributary Network Reorganization?

Deltas exhibit spatially and temporally variable subsidence, including vertical displacement due to movement along fault planes. Faulting-induced subsidence perturbs delta-surface gradients, potentially causing distributary networks to shift sediment dispersal within the landscape. Sediment dispersal restricted to part of the landscape could hinder billion-dollar investments aiming to restore delta land, making faulting-induced subsidence a potentially significant, yet unconstrained hazard to these projects. In this study, we modeled a range of displacement events in disparate deltaic environments, and observe that a channelized connection with the displaced area determines whether a distributary network reorganizes. When this connection exists, the magnitude of distributary network reorganization is predicted by a ratio relating dimensions of faulting-induced subsidence and channel geometry. We use this ratio to extend results to real-world deltas and assess hazards to deltaic-land building projects.

Automated summary

In this study, different displacement events in various deltaic environments were modeled to observe how channelized connections with displaced areas can determine if distributary networks will reorganize. It was found that the magnitude of distributary network reorganization can be predicted by a ratio relating dimensions of faulting-induced subsidence and channel geometry. This ratio was applied to real-world deltas to assess hazards to deltaic-land building projects.