How do V-notch weirs work in SWMM 5?

How do V-notch weirs work in SWMM 5?


The height of a V-Notch weir is the Height Value in the SWMM 5 Weir Property Dialog (Figure 1) 


The Length in the Dialog for a V-Notch is the Top Width of Triangular Shaped V-Notch Weir. 


The slope of the sides of the V-Notch Weir is Square Root (1 + Top Width / Height / 2 * Top Width / Height / 2)


The full area is the Height * Height * Side Slope


The hydraulic radius is the Height / ( 2 * Height * Side Slope)


The two values Height and Length for a SWMM 5 V-Notch Weir determines the area, hydraulic radius and side slope of the weir.


Figure 1.   Parameters for a V-Notch Weir in SWMM 5