--- title: "Headworks layout and cross sections" subject: "Irrigation and Drainage Engineering" chapter: 5 key: "semester_6/irrigation_and_drainage_engineering:headworks-layout-sections" source: https://www.bctengineer.com/q/semester_6/irrigation_and_drainage_engineering/headworks-layout-sections site: BCT Engineering --- # Headworks layout and cross sections Irrigation and Drainage Engineering · Chapter 5: Diversion Headworks - Asked in: 2069 Bhadra, 3+3+3+3 marks - Video: [Diversion Headworks](https://www.youtube.com/watch?v=h_zIgSEfzUM) — R Buragohain - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/irrigation_and_drainage_engineering/headworks-layout-sections - Whole chapter: https://www.bctengineer.com/md/semester_6/irrigation_and_drainage_engineering/chapter-5 ## Question Draw a neat sketch of the general layout of a diversion head works and cross sections of under sluices, canal head regulator and weir with all details. ## Short answer The layout comprises weir bays, divide wall, under sluices, head regulator, guide bunds, and fish ladder. Under sluice crest is at river-bed levele with gates, aprons, and sheet piles. Head regulator crest is 1.2–2.0 m higher, with gates and cutoffs. The weir has a raised crest with shutters, sloping glacis, stilling basin, and pile cutoffs. ## Answer #### (a) General layout (plan) ```text Marginal bund <------ river flow ------> ___________________________________________ | | | Weir bays | DW | Under- | DW | Head reg. |-> Canal |~~~~~~~~~~~| | sluice | | (gated) | | Fish ladder | pocket | silt excluder | |_________________|________|_______________| Guide bund (u/s) Guide bund (d/s) Upstream apron / Downstream apron, pile cutoffs ``` #### (b) Section of undersluice ```text Pond level ~~~~~~~~~~~~~~~~~~~~~ gate |#| pier/bridge deck ______|#|___ ___ d/s apron u/s crest (river-bed level) | | apron ------------------------ | | stilling basin sheet pile sheet pile ``` Crest at river-bed level; gate fixed above; u/s floor and cutoff; d/s hydraulic-jump floor with glacis, blocks and apron. #### (c) Section of canal head regulator ```text Pond level ~~~~~~~~~~~~~~~ |#| gate deck _______|#|______________ regulator crest (1.2-2.0 m above sluice crest) u/s apron | floor | piles | d/s apron -> canal ``` Crest is higher than the undersluice crest; piers carry gates and a bridge; floor with u/s and d/s cutoffs. #### (d) Section of weir ```text HFL ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Pond level ~~~~~~+--+ shutters __________| |\___ u/s apron crest \ glacis d/s floor ________________________ ______ apron sheet pile (cutoff) pile (cutoff) ``` Weir crest is raised by shutters above the permanent crest; the d/s sloping glacis dissipates energy by a hydraulic jump on the horizontal floor; u/s and d/s sheet piles control seepage; the aprons and filters protect against scour. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Where is the undersluice crest in its section? A. Above the weir crest B. At pond level C. At river-bed level D. At HFL Answer: C. The sluice crest is at river-bed level, with gate above it. (Key point: Undersluice section) 2. How is the head regulator crest placed relative to the undersluice crest? A. 1.2-2.0 m higher B. Equal C. 1.2-2.0 m lower D. At HFL Answer: A. It is higher to keep bed silt out. (Key point: Regulator crest) 3. How does the weir section dissipate energy? A. By a fish ladder B. By a hydraulic jump on the d/s horizontal floor after the glacis C. By the upstream apron D. By raising shutters Answer: B. The d/s glacis delivers flow to a horizontal floor where a hydraulic jump forms. (Key point: Weir section energy dissipation) 4. What are shutters on a weir crest for? A. Scouring silt B. Passing fish C. Measuring discharge D. Raising the crest above the permanent level for ponding Answer: D. Shutters raise the pond level above the permanent crest. 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