An open channel is a conduit in which water flows with a free surface. The free surface is subjected to atmospheric pressure. The classification of open channels are made based on different criteria as follows.

  • Classification Type 1
    1. Natural Channels
    2. Biya River

      Natural open channels include all channels that exist naturally on the earth. They are generally very irregular in shape.

      Example: Rivers, tidal estuaries etc.

    3. Artificial Channels
    4. California's Imperial Valley Artificial open channels are the channels develops by men. They are usually designed with regular geometric shapes.

      Example: Irrigation canals, laboratory flumes, spillway chutes, drops, culverts, roadside gutters etc.

  • Classification Type 2
    1. Prismatic Channels
    2. A channel with unvarying cross-section and constant bottom slope is called prismatic channel. All the artificial channels are usually prismatic. The rectangular, trapezoid, parabola and circle are the most commonly used shapes of prismatic channels.

    3. Non-prismatic Channels
    4. A channel with varying cross-section and constant bottom slope is called non-prismatic channel. The natural channels are usually prismatic.

  • Classification Type 3
    1. Rigid Boundary Channels
    2. A concrete-lined irrigation canal brings water from Merritt Reservoir on the Niobrara River

      A channel with immovable bed and sides is known as a rigid boundary channel.

      Example: Lined canals, sewers and non-erodible unlined canals.

    3. Mobile Boundary Channels
    4. alluvial channel

      If a channel boundary is composed of loose sedimentary particles moving under the action of flowing water, the channel is called a mobile boundary channel.

      Example: An alluvial channel is a mobile boundary channel transporting the same type of material that comprising the channel perimeter.

  • Classification Type 4
    1. Small Slope Channels
    2. An open channel having a bottom slope less than 1 in 10 is called a channel of small slope (Chow, 1959). The slopes of ordinary channels, natural or artificial, are far less than 1 in 10.

    3. Large Slope Channels
    4. An open channel having a bottom slope greater than 1 in 10 is called a channel of small slope (Chow, 1959). Some artificial channels like drops and chutes have far more than 1 in 10.