The tractive force method of channel design assumes equilibrium between acting and
permissible unit tractive forces, on level ground [channel bottom] and on the channel sides. The acting unit tractive forces coefficients
are determined from
the appropriate chart (Chow, 1959).
The permissible unit tractive forces for canals in noncohesive materials are determined from
the appropriate chart.
The angle of repose of the material on the sides is determined from the
appropriate chart also.
Given design discharge Q, side slope z, Manning's n, and bottom slope So,
the program can be used to determine the material properties (particle size and shape)
that will produce an optimum design, with a user-chosen aspect ratio
[the bottom width to normal depth (b/yn) ratio].
Alternatively, given certain material properties and a chosen aspect ratio, including the degree of
sinuosity, the program can calculate the design discharge under specified tractive force equilibrium.