River Morphology and Thresholds

Abstract

The regime geometry and channel patterns of alluvial rivers are analyzed Wing an energy approach together with physical relationships of flow continuity, flow resistance, and sediment transport. Because of the discontinuity in flow resistance, and thus in power expenditure, between lower and upper flow regimes, the adjustment in river regime consists of sudden changes in channel geometry, channel pattern, and sometimes silt‐clay content, when such a discontinuity is crossed. Thresholds or discontinuities in river morphology are obtained in the analysis. In accordance with such thresholds, rivers of distinct morphological features are classified into four regions based upon the bankfull discharge, channel slope, and median size of bed sediment. Their respective features are described, and certain regime relationships for channel width and depth are established. The predicted channel geometries are compared with river data.