Cohesive Surface Layers Transform Braided Channels Into Self‐Sustaining Meandering Channels With Repeated Cutoffs

Abstract

Meandering rivers are ubiquitous on Earth and other planetary surfaces, yet generating dynamically active meandering channels that can sustain meandering patterns for multiple flow cycles without introduced external disturbances remains challenging in laboratory conditions. Here, we use flume experiments to investigate how a synthetic cohesive surface layer, representing increased erosion resistance (associated with vegetation, biofilms, organic matter, and fine sediment) can reorganize an initially braided sand‐bed under an initial bed slope of approximately 1.6%. In the absence of cohesion, the channel maintained a multithread braided morphology. Following the introduction of surface cohesion to the floodplain and riverbanks, the system transitioned through wandering and single‐thread meandering states while remaining morphodynamically active, with continued bend migration, bend regeneration, and seven chute cutoffs. Quantitative classification using the channel count index and sinuosity confirms this transition from the initial braided toward more organized wandering and meandering configurations. Surface cohesion reduced the active channel area, and erosion and deposition rates, while localized bank erosion and channel migration continued. These results show that increased surface erosion resistance can suppress distributed channel and floodplain reworking without eliminating channel mobility, offering a vegetation‐independent mechanism for developing and maintaining dynamically active sinuous channels on Earth and other planetary surfaces.