--- title: "Components and layout of diversion headworks" subject: "Irrigation and Drainage Engineering" chapter: 5 key: "semester_6/irrigation_and_drainage_engineering:headworks-components-layout" source: https://www.bctengineer.com/q/semester_6/irrigation_and_drainage_engineering/headworks-components-layout site: BCT Engineering --- # Components and layout of diversion headworks Irrigation and Drainage Engineering · Chapter 5: Diversion Headworks - Asked in: 2079 Chaitra, 6 marks; 2063 Baisakh (old course), 8 marks (asked 2 times) - Video: [COMPONENTS OF DIVERSION HEADWORK | ANIMATED VIDEO LECTURE | GATE | ASSISTANT ENGINEER | SUB ENGINEER](https://www.youtube.com/watch?v=oBisIdBDcLo) — Amaze Academy for Civil Engineering - 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-components-layout - 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 headworks with all details and describe its components. ## Short answer Diversion headworks consist of a weir/barrage to raise level, undersluices to scour silt, divide wall to separate weir and sluice pocket, fish ladder for migration, head regulator to control canal flow, silt excluder/ejector, guide bunds, marginal bunds, aprons and pile cutoffs for scour and uplift protection. ## Answer A **diversion headworks** is a structure built across a river to raise the water level and divert the flow into a canal. It consists of a weir or barrage and the associated structures. #### Layout (plan) ```text Left <-- river flow: Upstream to Downstream --> guide ______________________________________ Right bund | | guide | Weir Weir |D| Under- |D| Head | bund ~~~> | (crest) bay |W| sluices |W| reg. | |=====================|======|====||===|--> canal | Fish ladder |<-- pocket -->| | | Divide wall (DW) separates weir/sluices |_______ Upstream & downstream aprons ___| Marginal / afflux bunds on both banks ``` (DW = divide wall; the head regulator is located at one end, with the silt excluder in front of it.) #### Cross-section through the weir ```text Pond level ~~~~~~~~~~~~~ u/s apron crest|\ d/s glacis ______________ ____| \_________ cutoff (sheet pile) | d/s pile ``` #### Components and their functions 1. **Weir or barrage proper** – raises the river level to the pond level and passes the flood over the crest (weir) or through gates (barrage). It has a crest, u/s and d/s glacis, and a floor with cut-off walls. 2. **Undersluices (scouring sluices)** – gated openings at low level next to the canal head, which scour deposits in front of the head regulator and pass low floods. 3. **Divide wall** – separates the weir portion from the undersluice portion, protects the sluices from cross currents, and forms the still pocket. 4. **Fish ladder** – a sloping channel with baffles beside the divide wall, allowing fish to migrate. 5. **Canal head regulator** – controls the flow into the canal; its crest is higher than that of the undersluices to keep out bed silt. 6. **Silt excluder / silt ejector** – reduce silt entry into the canal. 7. **Guide bunds (guide banks)** – train the river to flow axially through the structure and prevent outflanking. 8. **Marginal (afflux) bunds** – protect the land and villages upstream from flooding caused by the raised water level (afflux) behind the structure. 9. **Aprons and protection works** – u/s and d/s concrete blocks with filters and launching aprons, to protect against scour. 10. **Pile cutoffs / curtain walls** – at the upstream and downstream ends of the floor, to lengthen the creep path and keep the exit gradient safe. 11. **Piers, bridge, and shutters/gates** – for operation of the gates and cross-communication. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is a diversion headworks? A. A structure across a river that raises water level and diverts flow into a canal B. A canal drop structure C. A reservoir for flood storage D. A distributary outlet Answer: A. It is built across a river to raise the level and divert flow into a canal. (Key point: Purpose of headworks) 2. Which is a function of the divide wall? A. Passing floods B. Separating the weir from the undersluices and forming the silt pocket C. Measuring discharge D. Producing hydraulic jump Answer: B. The divide wall separates weir flow from the pocket and protects the sluices from cross currents. (Key point: Divide wall) 3. What do guide bunds do? A. Store water B. Raise the pond level C. Train the river to flow axially through the structure D. Control exit gradient Answer: C. Guide bunds train the river to approach the structure straight. (Key point: Guide bunds) 4. How does the head regulator crest compare with the undersluice crest? A. Equal B. Lower C. Depends on the canal D. Higher, to keep out bed silt Answer: D. A higher crest keeps bed silt out of the canal. (Key point: Regulator crest level) ## Related in Irrigation and Drainage Engineering - [Headworks layout and cross sections](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Aheadworks-layout-sections) — Irrigation and Drainage Engineering, chapter 5 - [Layout planning of surface drainage system](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Asurface-drainage-layout-planning) — Irrigation and Drainage Engineering, chapter 9 ## Related in other subjects - [General requirements of functional RoR headworks](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Aror-headworks-requirements-only) — Hydropower Engineering, chapter 5, asked 2× - [Layout of hydropower scheme components](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Ahydropower-scheme-layout) — Hydro Power, chapter 5 - [RoR headworks arrangement and functional requirements](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Aror-headworks-arrangement-requirements) — Hydropower Engineering, chapter 5, asked 3× - [Diversion type storage plant characteristics](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Adiversion-storage-plant-characteristics) — Hydropower Engineering, chapter 2