Rationalized Energy‐Loss Parameters for Channels

All hydraulic computations involving flow in open channels require an evaluation of energy‐loss parameters. A fundamental approach is to assess the different types of energy loss separately. Methods of doing this are described, including a new method using the concept of friction distance and dummy boundaries for computing flow through vegetation. Dummy boundaries are also useful where there is dead water or a large eddy, but care is needed in assessing form losses to account for the assumed flow pattern in the reduced cross section. The parameters used are reasonably easy to assess and are less variable with depth than Manning's n‐values. The method described is less subject to limitations due to lack of measurements in a given river. This is because each parameter is based on a physical feature that can be measured or estimated.