ABSTRACT
Open-channel ¡ows can be classied into many categories according to how the depth of the ¡ow changes with respect to time and position:
• Steady ow exists if the volume ¡ow rate does not change during the interval of interest. • Unsteady ow exists if the volume ¡ow rate does change with time. (Floods and surges
are examples.) • Nonuniform ow exists in a channel if liquid enters or leaves along the course of the
¡ow. This type is also known as spatially varied or discontinuous ¡ow. (Flow in roadside gutters, main drainage canals, ¡ood surges, and feeding channels of irrigation systems are examples.)
• Uniform ow exists if the depth is uniform (i.e., unchanging) at every section of the channel. Uniform ¡ow occurs when the ¡ow is steady.
