A study of stream braiding

Abstract

Stream braiding has always been a poorly-understood subject, which needs thorough investigation before the control of braided rivers by engineering works can be rationalised. The lack of such understanding has resulted in makeshift river-training measures employed in controlling major braided rivers in New Zealand, where the unpredictable behaviour of these rivers has brought serious social and economic effects. The present study has three aims: firstly, to establish a method by which a braided stream can be geometrically described by the use of some parameters devised herein; secondly, to investigate the extent to which a very small braided stream can serve as a model of less rigorous nature of a large braided river since braided channel patterns produced in the laboratory were strikingly similar to those in the natural river; and lastly, to study the sequential development of braiding in a small-scale laboratory stream which was different from developments previously reported in the literature. These aims are served by small-scale laboratory experiments on braided streams running in sand, and by comparing the results of these experiments with field observations of the Rakaia river.