Some space‐filling controls on the arrangement of tributaries in dendritic channel networks

Abstract

The arrangement of tributaries in dendritic channel networks is controlled in part by the relationship between the spatial requirements of the tributaries and the availability of space. An investigation of 6105 tributaries in four dendritic networks reveals that the arrangement of tributaries of different sizes along subbasin main streams is influenced by two constraints on the availability of space on the acute side (inside) of the main streams. The first constraint arises from the tendency for semidivide angles (between the main stream and adjacent divides) at subbasin outlets to be larger on the obtuse (outside) than on the acute side of the main stream. This constraint not only causes a higher proportion of large tributaries than small ones to form on the obtuse side of subbasin main streams near their outlets but favors the development of large tributaries on the obtuse side farther upstream than small ones. The second constraint is imposed by the tendency for subbasin main streams to curve upstream. This constraint affects tributaries that are almost as large as the subbasin main stream they join and, like the first constraint, it favors the formation of large tributaries on the obtuse side farther upstream than small ones.