Description

Given the basic characteristics of a trapezoidal channel in uniform flow, calculate:

• Normal flow depth
• Flow
• Roughness coefficient ($n$)
• Slope

Trapezoidal Channel Diagram

Calculation Methods

1. Depth

   • Inputs

     Parameter	Default Unit	Description
     Flow ($Q$)	$m^3/s$	Volumetric flow rate
     Inferior width ($b$)	$m$	Base width of the channel
     $Z1$	-	Left side slope
     $Z2$	-	Right side slope
     Slope ($I$)	-	Channel slope
     Roughness coefficient ($n$)	-	Channel roughness

   • Outputs

     Parameter	Default Unit	Description
     Normal flow depth ($y$)	$m$	Computed flow depth
     Superior width ($B$)	$m$	Total width at the top of the channel
     Velocity ($U$)	$m/s$	Average flow velocity
     $U^2/2g$	-	Energy term per unit mass

2. Flow

   • Inputs

     Parameter	Default Unit	Description
     Depth ($y$)	$m$	Flow depth
     Inferior width ($b$)	$m$	Base width of the channel
     $Z1$	-	Left side slope
     $Z2$	-	Right side slope
     Slope ($I$)	-	Channel slope
     Roughness coefficient ($n$)	-	Channel roughness

   • Outputs

     Parameter	Default Unit	Description
     Flow ($Q$)	$m^3/s$	Computed flow rate
     Superior width ($B$)	$m$	Total width at the top of the channel
     Velocity ($U$)	$m/s$	Average flow velocity
     $U^2/2g$	-	Energy term per unit mass

3. Inferior width ($b$)

   • Inputs

     Parameter	Default Unit	Description
     Depth ($y$)	$m$	Flow depth
     Flow ($Q$)	$m^3/s$	Volumetric flow rate
     $Z1$	-	Left side slope
     $Z2$	-	Right side slope
     Slope ($I$)	-	Channel slope
     Roughness coefficient ($n$)	-	Channel roughness

   • Outputs

     Parameter	Default Unit	Description
     Inferior width ($b$)	$m$	Base width of the channel
     Superior width ($B$)	$m$	Total width at the top of the channel
     Velocity ($U$)	$m/s$	Average flow velocity
     $U^2/2g$	-	Energy term per unit mass

4. Roughness coefficient ($n$)

   • Inputs

     Parameter	Default Unit	Description
     Depth ($y$)	$m$	Flow depth
     Flow ($Q$)	$m^3/s$	Volumetric flow rate
     Inferior width ($b$)	$m$	Base width of the channel
     $Z1$	-	Left side slope
     $Z2$	-	Right side slope
     Slope ($I$)	-	Channel slope

   • Outputs

     Parameter	Default Unit	Description
     Roughness coefficient ($n$)	-	Computed channel roughness
     Superior width ($B$)	$m$	Total width at the top of the channel
     Velocity ($U$)	$m/s$	Average flow velocity
     $U^2/2g$	-	Energy term per unit mass

5. Slope ($I$)

   • Inputs

     Parameter	Default Unit	Description
     Depth ($y$)	$m$	Flow depth
     Flow ($Q$)	$m^3/s$	Volumetric flow rate
     Inferior width ($b$)	$m$	Base width of the channel
     $Z1$	-	Left side slope
     $Z2$	-	Right side slope
     Roughness coefficient ($n$)	-	Channel roughness

   • Outputs

     Parameter	Default Unit	Description
     Slope ($I$)	-	Computed channel slope
     Superior width ($B$)	$m$	Total width at the top of the channel
     Velocity ($U$)	$m/s$	Average flow velocity
     $U^2/2g$	-	Energy term per unit mass