Design Criteria for Irrigation Canals - Sediment Transport in Irrigation Canals: A New Approach - page 85

Diameter D

Figure 4.11. Submerged culvert
or siphon (Paudel, 2010).

Pipe length L

culvert (see Figure 4.11). The total energy loss in a pipe (culvert, siphon)
is estimated as (Depeweg, 2000):

f L
D

v 2
2 g +

ξ 1 v 2
2 g

h = (4.43)

The first term at the right hand side represents the friction loss and
the second term the entrance, bend, exit and all the other local losses.
The friction factor f depends upon the type of construction material and
condition of the culvert. The value of ζ 1 can be determined from references
or field measurements.

Summary
In general the depth discharge equation can be written as:

µCBh 2 gh Q = (4.44)

where:
Q = (discharge)

C = discharge coefficient

B = width of control section (m)

h = difference in head (m)

h = water depth (m)

µ = coefficient for the modular limit; the coefficient for the modular

limit µ is 1 for these structures with free flow conditions.

The values of the variables for different structures and flow conditions
are as shown in Tables 4.8 and 4.9.
The upstream energy head ( H 1 ) is computed from:

V 1 Q 2

2 gB 2 y 1

H 1 = h 1 +

2 g =

h 1 + (4.45)

For y 1 is the upstream water depth which results in:

y 1 = h 1 + P (4.46)

where:
P is the crest height with reference to the upstream bed (m)