ABSTRACT

The characteristic feature of all channel flow is the presence of a free surface. As used in the present context the word ‘channel’ has a wide meaning since it is deemed to embrace river channels as well as artificial channels, such as canals and flumes; also included are enclosed con­ duits (e.g. sewers and culverts) operating partially full. Specifically excluded are pipes operating under pressure, which always flow full. Unlike pipe flow the hydraulic gradient is coincident with the free sur­ face of the water and the sectional area of flow expands or contracts in conformity with the discharge.