Environmental Engineering Reference
In-Depth Information
APPENDIX A
Methods to Estimate the Total Sediment
Transport Capacity in Irrigation Canals
A.1 INTRODUCTION
The design and operation of irrigation canals are based on the principle
that no deposition or erosion occurs during certain periods. Good designs
of an irrigation network as well as a well-operated irrigation system
require an accurate prediction of the sediment transport of irrigation
canals.
There is no universally accepted equation to determine the total trans-
port capacity of sediment in irrigation canals. Many methods predict the
sediment transport under a large range of flow conditions and sediment
characteristics. The available prediction methods include the methods of
Lane-Kalinski (1941), Einstein (1950), Colby (1964), Bishop et al. (1965),
Bagnold (1966), Engelund-Hansen (1967), Chang et al. (1967), Toffaletti
(1969), Ackers-White (1973), Yang (1979), Brownlie (1981), van Rijn
(1984), etc. However, the predictability of all of them is still poor. Van
Rijn (1984) stated that it is impossible to predict sediment transport with
an accuracy of less than 100%. Therefore, it is quite difficult to make firm
recommendations about which method to use in practice. Nevertheless,
a comparison of sediment transport methods under the typical flow con-
ditions and sediment characteristics of irrigation canals could become a
powerful tool to reduce inevitable errors and inaccuracy. It is not possible
to check all the existing methods to predict sediment transport. In these
notes five of the most widely used methods to compute sediment transport
will be presented. These methods are:
•
Ackers-White;
•
Brownlie;
•
Engelund-Hansen;
•
Van Rijn;
•
Yang.
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