a] Uniform flow: When the velocity of flow, depth of flow, slope of the channel and cross section remain constant for a given length of the channel, the flow is said to be uniform.

$\frac{\delta y}{\delta s} - 0$ , $\frac{\delta v}{\delta s} = 0$ (uniform)

b] Types of flow in channels :

1] Steady flow and unsteady flow.

2] Uniform flow and non uniform flow.

3] Laminar flow and turbulent flow.

4] Sub critical, super critical flow.

c] 1] Steady flow : If all the characteristics of flow, i.e. depth of flow, velocity of flow, rate of flow at any point in open channel flow do not change with respect to time, the flow is said to be steady flow.

It is expressed as:

$[\frac{ \delta v}{\delta t} = 0], [\frac{\delta Q}{\delta t} = 0] or [\frac{\delta y}{\delta t} = 0]$

where, v = velocity,

Q = discharge,

y = depth of flow.

2] Unsteady flow: when the characteristics of flow, i.e. the velocity of flow, depth of flow, rate of flow at any point in open channel flow changes with respect to time, the flow is said to be unsteady flow.

$ [ \frac{ \delta v}{\delta t} \neq 0] , [ \frac{\delta y}{\delta t} \neq 0] or [ \frac{\neq }{\delta t} \neq 0]$

3] Laminar flow: The flow is said to laminar, if the Reynolds number (Re) is less than 500 or 600 (Re < 500, 600)

Reynolds number in case of open channels is defined as:

$Re = \frac{ρvr}{\mu}$

where, v = mean velocity of flow of water

R = hydraulic radius

ρ = density

$\mu$ = viscosity of water.

4] Turbulent flow: If the Reynolds number is more than 2000, the flow is said to be turbulent in open channel flow, if Re lies between 500 to 2000, the flow is considered to be in transition state.

5] Sub critical flow: If the fraude number (fe) is less than 1.0 then, the flow in open channel, is said to be sub critical.

$fe = \frac{v}{\sqrt90}$

v = mean velocity of flow

D = hydraulic depth of channel.

6] Super critical flow: If the fraud number is greater than 1.0 (fe > 1.0) then, the flow in open channel is said to be super critical.

7] Prismatic channels: A channel with un varying cross section and the constant bottom slope is called prismatic channel. all the artificial channels are usually prismatic commonly used shapes rectangular, trapezoid, parabola, circle.

8] Non prismatic channels : A channel with either varying cross section or varying bottom slope is called as non prismatic channel.