Experiments were performed in a large flume at constant discharge to determine the effect of slope on channel patterns. At very low slopes (< 0.2%), the model channels remained straight, but a meandering-thalweg channel formed at steeper slopes (between 0.2 and 1.3%), and braided channels formed at the steepest slopes (> 1.3%). These experiments demonstrate that channel patterns can change from straight to meandering to braided at critical values of slope.

The results also are applicable to the problem of the downstream variability of river patterns. Most alluvial rivers flow on surfaces (valley floor or alluvial plain) whose slopes have been determined by past conditions of flow and sediment load, by tributary effects, and/or by warping. As channel patterns are sensitive to changes of slope, other conditions being similar, a steeper reach of valley slope usually will cause an increase in channel sinuosity, as the river attempts to maintain a relatively constant gradient. Experimental results and Mississippi River data support this conclusion, which may be of practical value in identifying reaches of a river system influenced by neotectonics or structure.

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