Interplay of river and tidal forcings promotes loops in coastal channel networks

TL;DR

This paper presents a model explaining the formation of loops in coastal channel networks driven by the interplay of river and tidal forces, supported by field data and satellite imaging.

Contribution

It introduces a self-organizing network model inspired by vascular biophysics to explain loop formation in coastal channels, a phenomenon not previously understood.

Findings

Loops form when river and tide forcings are comparable.

Field data confirms the control of hydrodynamic fluctuations on loop formation.

Hydrodynamic fluctuations promote loop formation in coastal networks.

Abstract

Global coastlines and their dense populations have an uncertain future due to increased flooding, storms, and human modification. The distributary channel networks of deltas and marshes that plumb these coastlines present diverse architectures, including well-studied dendritic topologies. However, the quasi-stable loops that are frequent in many coastal networks have not yet been explained. We present a model for self-organizing networks inspired by vascular biophysics to show that loops emerge when the relative forcings between rivers and tides are comparable, resulting in interplay between processes at short timescales relative to network evolution. Using field data and satellite imaging, we confirm this control on 21 natural networks. Our comparison provides the first evidence that hydrodynamic fluctuations promote loop formation in geophysical systems.