[MTC]

Equation 6-1 in the DAMBRK User’s Manual specifies that the terminal breach width (b) is equal to the average width (bbar) times one-half the slope (Z) times the dam height (hd), or

b = bbar – 0.5 Z hd.

Many sources, including the NWS DAMBRK Model: Theoretical Background/ User Documentation by Fread, 1988, as well as basic geometry, suggest that

b = bbar – Z hd (not 0.5 Z hd)

Is this a miss print, or does the user manual define the average base width differently, such as a time dependent average?

I assume the average base width is equivalent to the average width of a trapezoid, or 1/2 times the top width minus the bottom width. Is this correct?