| Abstract: | Meandering is one of the most complex problems associated with the behavior of rivers. Several explanations (derived from both field and laboratory flume) have been advanced to account for stream meandering, among them being the earth's rotation, excess current energy, transverse oscillations, initial current deflection, local disturbances, changes in stages of discharge and bed load and helicoidal flow. Foremost among these is the effects of helicoidal flow within the stream flow. The purpose of this paper is to review and analyze selected meander theories that contribute either directly or inherently to current meander concepts which revolve around the effect of helicoidal flow.Prevalent ideas concern meandering as being dependent not only on stream flow but also on the rate of stream discharge, sediment load, size and type of sediment, channel roughness, depth, width, velocity of flow, and quality of water itself. The characteristics of helicoidal flow seem to be the best explanation for the development of meanders. Theories for meandering do not clearly explain the cause of helicoidal flow. Most of its intricacies have been learned through laboratory flume experiments. Interestingly, earlier work on river meandering was the product of long days in the field; in more recent years such research has been undertaken in the laboratory. One feels that a return to the stream would be a healthy complement to flume measurements. Further study should include hypothesis testing in a variety of material both homogeneous and heterogeneous. |
