Changes in stream channel characteristics at tributary junctions

Several existing data sets are analyzed empirically to determine the nature of changes in channel characteristics at stream confluences. Classifications of the data indicate that such changes are diverse and do not conform well with predictions based on the hydraulic geometry of synchronous channel-forming flows on major and minor tributaries. Scatterplots reveal that at best only weak relation ships exist between rates of change for the variables and junction symmetry ratio. Most of the plots display abrupt discontinuities separating positive and negative changes at low symmetry values from changes at high symmetry values that are positive or negative only. These thresholds of discontinuity generally occur at a symmetry ratio of approximately 0.7. Such thresholds may be indicative of abrupt changes in the factors controlling junction morphology. More research is required both at site-specific and basin-wide scales to resolve this issue.