Description of the Main Aspects of the Regime Theory - Sediment Transport in Irrigation Canals: A New Approach - page 269

this might be done by modifying the cross-sections of the existing canal
and in other places by changing the structures, raising the banks and
forcing the larger water supply to flow in the canal. Often this has resulted
in a change of the canal regime established in the past and in unsymmetrical
cross sections.

D.7 DESIGN CONSIDERATIONS

To design a straight, earthen canal that has to convey a certain amount of
water and sediment three equations are needed to find the bottom width,
water depth and bottom slope of the canal. However, normally there are
only two equations available, namely a flow equation (Manning, Strickler
or de Chézy) and a sediment transport equation. An equation to describe
the shape of a stable channel is not yet available. If the tractive force along
the canal perimeter is large enough to maintain sediment transport, one
can rely on a kind of regime-like relationship to describe the stability of
the canal (Bettes, et al., 1988).
The limitation of this theory is that it assumes that the discharge is the
only factor determining the wetted perimeter of the canal while the fact is
that canals with less stable banks tend to be wider than those with strong
banks for the same discharge.
Simons and Albertson (1963) developed a set of regime equations
based on a large data set collected from canal systems in India and North
America. Five types of canals were identified from the collected data set
and for each category the coefficients are given for the design of a canal as
shown in Table D.2. Simons and Albertson's equations have a wide range
of applicability and the data set used is related to a sediment load of less
than 500 ppm (Raudkivi, 1990). The set of regime equations of Simons
and Albertson (1963) is:

K 1 Q P = (D.5)

B = 0 . 9 P = 0 . 92 B s − 0 . 61 (D.6)

K 2 Q 0 . 36 R = (D.7)

h = 1 . 21 R for R < 2 . 1 m (D.8)

h = 0 . 61 + 0 . 93 R for R > 2 . 1 m (D.9)

K 3 ( R 2 S ) n v = (D.10)

K 4 vB
ν

0 . 37

C 2
g =

v 2
gDS =

(D.11)