Planform Geometry–Migration Relation in Meandering Rivers with Complex Bends

The complex forms of meander planforms, such as compound looping and double heading, are fairly common features of natural meandering rivers. Nevertheless, they cannot be reproduced by theoretical meander migration models assuming the effect of upstream planform curvature on local migration rates as an exponential decay. In this study, we explore empirically the spatial relationship between planform geometry and migration of meandering rivers, particularly containing compound loops and double heads, based on the meander train data obtained from aerial photography. In search of the structure of such a spatial relationship, we resort to various discrete-time signal processing techniques, ranging from basic frequency domain analysis to advanced multi-rate approaches. The results demonstrate the capability of discrete-time signal processing for uncovering the spatial relation between planform geometry and migration of meander planforms. The results also suggest that the effect of planform geometry on migration behavior of compound loops and double heads is complex, a finding that coincides with the findings of an empirical study on the curvature-migration relation and the assumptions of the recently developed high-order theoretical migration models.