CIVIL WORKS GUIDELINES FOR MICRO-HYDROPOWER IN NEPAL
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Photo 4.5 An oil drum irrigation canal, Ecuador.
Photo 4.6 Timber canal with bracing supporting the sides,
Thuptenchuling.
Box 4.1 Canals with semi-circular concrete sections
Practical Action has developed semi-circular formers in Peru
as a means of reducing costs of materials for concrete ca-
nals. These are fabricated from 50 mm x 50 mm x 6 mm steel
angles with transverse flats welded at the top to provide stabil-
ity as shown in the photograph. These are placed at certain
intervals as guides for the shape of the canal. When com-
pared to trapezoidal sections designed for similar flows
(801/s in this case) and installed adjacent to the semi-circular
section, the savings in materials were calculated to be around
20 per cent in cement, sand and gravel. However, labour costs
were about 50 per cent higher due to the greater demand of
excavating, placing and finishing concrete.
Photo 4.7 A semi- ciruclar concrete canal section, El Tinte, Peru