Skip to main content

Headworks sketch, regulator section, protection works

Short answer

An irrigation headworks includes weir, undersluice, divide wall, head regulator, silt excluder, and guide bunds. Head regulator longitudinal section has upstream floor with cut-off, gated raised crest, stilling basin with chute blocks as energy dissipaters, and downstream inverted filter with stone apron for protection.

Drawing a neat sketch of an irrigation headworks, draw a longitudinal section through a head regulator showing upstream floor, regulator gates; energy dissipaters and protection works.

Sketch of an irrigation headworks (3 marks)

              River flow --->
 left  ___________________________________  right
 bank |  Left  |  Weir/Barrage | Under- |  Right
 -----|  guide |  bays (gated) | sluice |  guide
      |  bund  |===============|========|  bund
 Head |regul-  |               | Fish   |
 reg. |ator    |<-silt excluder| ladder |
 -----+--------+---------------+--------+------
 canal                       Marginal bund

The components are the weir or barrage, undersluice (with divide wall), canal head regulator, silt excluder, fish ladder and guide bunds with marginal bunds.

Longitudinal section through the head regulator (3 marks)

 Pond level ~~~~~~~~~|G|~~~~~~~~~~ canal FSL ~~~~~
 u/s cut-off  u/s apron | crest  | d/s floor | d/s
  ___|________ _________|__gate__|___________|cutoff
 |   upstream floor     raised     stilling basin
 |                      crest      with chute blocks
 |___ impervious floor ________|_ inv. filter _|apron_
  • Upstream floor: impervious, with cut-off, to reduce uplift and exit gradient.
  • Regulator gates: vertical lift gates between piers on a crest raised above the river bed.
  • Energy dissipaters: stilling basin/cistern with a hydraulic jump, with chute blocks and end sill, d/s of the gates.
  • Protection works: inverted filter, loose stone apron and d/s cut-off to protect against scour and piping.

✓ Answer checked by Claude Opus 5.5 (high effort)

Related questions

All Irrigation and Drainage Engineering chapter 7 questions →