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What is an intake? Functions and sketch

Short answer

An intake is the structure that withdraws design discharge from the river into the conveyance system. Its functions: divert required flow, control with gate, exclude bed load and trash via sill and rack, limit sediment entry, and provide smooth transition. The sill is 1.0-1.5 m above the undersluice bed to prevent bed load entry.

What do you mean by an intake? Write down its functions and sketch a generalized intake structure for a RoR diversion project.

Definition

An intake is the structure at the head of the water conductor system that withdraws the design discharge from the river (or reservoir) and admits it into the canal, tunnel or pipe in a controlled way.

Functions

  • Diverts the required discharge into the conveyance system at all river levels.
  • Controls the flow with a gate; shuts it off for inspection and during floods.
  • Excludes the bed load and the floating trash and debris through the sill, trash rack and trash boom.
  • Limits the entry of sediment and passes it to the gravel trap and settling basin.
  • Provides a smooth, low-loss transition and prevents air entry and vortices.

Sketch of a generalized RoR intake

PLAN
 river ===>  ||||||||||| weir
                 __________________________
 undersluice =|  trash rack  gate   |==> approach
 (flushing)   |_____________________|    canal

SECTION
  pond ~~~~~~~~~~~~~~~~~~
        |    | rack   ____ gate
        |    |##   \ |    |
  sill  |____|##____\|____|=====> canal
  ///////////////// river bed (undersluice lower)

The sill of the intake is kept 1.0-1.5 m above the bed of the undersluice so that bed load cannot enter; the opening is sized so that the velocity at the trash rack is about 0.8-1.0 m/s.

✓ Answer checked by Claude Opus 5.5 (high effort)

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