Length scale of braided river morphology

Pool‐bar topography in single‐channel rivers has a length scale proportional to channel width. In braided rivers confluence‐bifurcation units are analogous to pool‐bar morphology and, in some cases, develop from initial alternate bars. Consequently, confluence‐bifurcation units are expected to have length that scales with the central anabranch width and that constitutes a basic length scale braided channel morphology. This idea was tested using measurements from a physical model of a gravel bed braided river and from aerial photographs of braided rivers. Length (distance from confluence to bifurcation), anabranch width, and confluence angle of confluence‐bifurcation units were measured. A simple length scaling is evident across the range of scales; confluence‐bifurcation length is 4–5 times the channel width. This scaling is a fundamental element of braided river morphology and suggests that braided patterns are created by processes, and have morphological regularity, similar to pool‐bar units of low‐sinuosity single‐thread rivers.