On-line version ISSN 1816-7950
RAHIMPOUR, Majid. Effects of free-surface on design charts for open channels. Water SA [online]. 2012, vol.38, n.1, pp. 145-148. ISSN 1816-7950.
Normal depth is an important parameter for the design of channels and canals. For rectangular, trapezoidal, and circular channel sections it is possible to express normal depth by a trial-and-error procedure or analytically. However, the effects of free-surface on the design charts for determination of the normal depth are not investigated. In this paper, graphical solutions of normal depth for the rectangular, trapezoidal, and circular cross-sections have been obtained in the non-dimensional form. To evaluate the resistance effects of the free-surface in the calculation of the normal depth, the dimensionless-form of Manning';s equation with free-surface weight factor is introduced herein. The design charts reported previously were modified.
Keywords : Open-channel flow; normal depth; free-surface effect.