Hydraulic Design of Irrigation Canals - Sediment Transport in Irrigation Canals: A New Approach - page 260

C.9 FINAL REMARKS
The design of a canal section starts from a given discharge Q and looks
for the following unknown canal characteristics:
1. the bottom width b ;
2. the side slope m ;
3. the roughness (smoothness) of the canal, k s or C ;
4. the water depth y ;
5. the range for the bottom slope S o ;
a. the minimum recommended slope;
b. the maximum allowable slope.
The steps for the design of a canal as discussed in the previous section
include:
1. the equation for uniform flow;
2. a side slope m that depends on geological criteria;
3. a value of k s that is a function of the maintenance condition and the
water depth y ;
4. the recommended value for the b / y -ratio;
5. the sediment aspects:
a. the criterion in view of the erosion (tractive force);
b. the criterion to prevent sedimentation by controlling the relative
transport capacity.
This iterative design process can be easily used for the development
of a spreadsheet or a Visual Basic programme that uses all the presented
criteria and equations, including the criteria for bed erosion and sediment
transport. UNESCO-IHE has developed programs like Candes and Sysdes
for the design of a single canal reach or a canal network with several
sections, respectively.
After finalizing the design of the canal, next the model SETRIC can
be applied to evaluate the design and to analyze the alternatives. The
model can also be used as a decision support tool in the operation and
maintenance of the irrigation network and to determine the efficiency of
sediment removal facilities in the system. In addition to that the model
will be helpful for the training of engineers to enhance their understanding
of sediment transport in irrigation canals.
C.10 COMPUTER AIDED DESIGN OF CANALS
At present various stand-alone programs are available for the design of
irrigation canals that allow the designer to evaluate a specific part of the
design. In the past years UNESCO-IHE has looked for an integrated tool
that combines some of the solitary programs and that results in a faster