1. Title slide:
Sediment control
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2. Canal head reach showing sediment deposits above the water
level restricting flow into the canal (Yemen Arab Republic).
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3. Sediment deposits up to 1.3 metres deep occupy most of
the design cross-section of this canal (Nepal). |
4. Sediment deposits almost completely blocking canal gates
(Yemen Arab Republic). |
5. Manual desilting work in a small canal (Indonesia). |
6. Men, women and children desilting a 40m3/s canal (Nepal).
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7. Bulldozer removing sediment deposits from a 15m3/s canal
(Philippines). |
8. Excavator desilting a branch canal (Philippines). |
9. Sediment deposits removed from a minor canal (The Sudan).
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10. Water being diverted from a river to a small irrigation
canal by a deflector constructed by farmers (Yemen Arab Republic).
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11. Barrage controlling the River Kosi at the India/Nepal
border. The gated section is just over 1km long and consists
of 46 spillway gates and 10 sluice gates. |
12. Plan of an irrigation intake typical of that used in medium
scale irrigation schemes. |
13. Irrigation intake under construction showing, from left
to right, the weir, the gated sluiceway and the gated canal
intake (Malawi). |
14. Flushing sediment deposits that have built up in front
of an intake (Thailand). |
15. An irrigation intake operating with the sluice gates partially
open. About 50% of the discharge being diverted to the canal
is passing through the sluice, carrying the larger sediments
past the canal gates. |
16. Use of a tunnel to separate flow carrying high sediment
concentrations near the bed of a channel from the relatively
sediment-free upper layers. |
17. Line drawing illustrating the use of a canal sediment
extractor to divert sediment back to the river by an escape
channel. |
18. Cross-section through a vortex tube sediment extractor.
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19. The entry slits of a multiple tube vortex tube sediment
extractor (Nepal). |
20. Plan view of a typical settling basin layout. |
21. A settling basin at the head of a 3m3/s canal (Indonesia).
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22. A settling basin at the head of a 20m3/s canal (Indonesia).
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23. Flushing sediment from a settling basin through the flushing
sluices (Indonesia). |
24. A twin settling basin (Indonesia). |
