Influence of Geometry on Discharge Capacity of Open Channels

Abstract

An experimental investigation of the influence of cross-sectional geometry on the discharge capacity of rectangular and compound channels is presented. It is found that a wide rectangular channel carries as much as 80% less than a narrow rectangular shape, and as much as 25% less than a compound shape of the same overall width, for the same cross-sectional area, and bed slope. Comparison of friction factors reveals that values in a wide rectangular channel could be as much as 45% greater than in a narrow rectangular section, and as much as 25% greater than in a compound section of the same overall width. The findings show the danger of ignoring shape effects in open channels, and underline the need for a systematic investigation of their influence on discharge capacity.