A Classification of Alluvial Channel Systems

Abstract A new classification of alluvial channel systems is proposed, based on the braiding parameter: the number of braids per mean meander wavelength, braids being defined by the mid-line of the channels surrounding each braid bar. Single-channel and multi-channel systems are defined as having braiding parameters less than and more than one, respectively. Channel systems are further divided into low-and high-sinuosity categories at the boundary 1.5, giving four types, of which single-channel high-sinuosity (meandering) and multi-channel low-sinuosity (braided) are by far the most common. The other two types are much less abundant: single-channel low-sinuosity (straight), and multi-channel high-sinuosity (anastomosing). The classification can be applied to ancient alluvial deposits through an understanding of the processes that relate channel morphologies to their resulting sedimentary suites. As the processes are imperfectly understood, so the application to paleochannels is imprecise. However, it can be made satisfactorily in most cases, provided maximum use is made of the channel-process information in alluvial sedimentary models.