--- title: "RoR headworks sketch; intake importance and location" subject: "Hydropower Engineering" chapter: 5 key: "semester_7/hydropower_engineering:ror-headworks-arrangement-intake-location" source: https://www.bctengineer.com/q/semester_7/hydropower_engineering/ror-headworks-arrangement-intake-location site: BCT Engineering --- # RoR headworks sketch; intake importance and location Hydropower Engineering · Chapter 5: Headworks of Run-of- River (RoR) Plants - Asked in: 2080 Bhadra, 2+2+2 marks - 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_7/hydropower_engineering/ror-headworks-arrangement-intake-location - Whole chapter: https://www.bctengineer.com/md/semester_7/hydropower_engineering/chapter-5 ## Question Draw a neat sketch showing the typical arrangement of components of a headworks of a RoR hydropower project. Write down the importance of its intake. How do you decide the location of an intake in a river? ## Short answer The intake is the link between river and waterway; it controls sediment, trash, head loss and flow safety. Locate it on the outer bank of a bend, in a stable reach, upstream of the weir next to the undersluice, away from confluences, where the river is narrow and access is good. ## Answer #### Typical arrangement of the headworks ```text PLAN river flow ==============================> left bank wall +-------------------------------------------+ | intake | undersluice | weir (spillway) | | (side) | (gates) | ||||||||||||||||| | +----+-----+-------------+--------------------+ | gravel trap v fish ladder approach canal --> settling basin --> headrace ``` ```text SECTION through weir, undersluice and intake pond level ~~~~~~~~~~~~~~~~~~~~~~~~~~ _____ weir crest ______ intake|rack |gate / \ stilling basin sill |_____|-> canal / \____ apron /////////// undersluice ///////// river bed (sill 1.0-1.5 m above bed) flushing gate ``` #### Importance of the intake - It is the **link between the river and the waterway**: the whole plant depends on it for the design discharge. - It controls the **quality of water** entering the plant: sediment, gravel and trash that pass the intake reach the settling basin, tunnel and turbines and cause abrasion and blockage. - It decides the **head loss** and so the energy generated; a poor intake gives vortices, air entry and heavy losses. - It provides **flow control and safety**: gates close during floods and for maintenance. - A wrongly placed intake can silt up, so its location and design decide the **life and reliability** of the headworks. #### Deciding the location of an intake 1. On the **outer bank of a bend** (about one-third to one-half way along the bend, downstream of the bend apex), where the helical flow carries bed load away from the opening; on a straight reach put it on the stable bank. 2. In a **stable reach with a good foundation**, free of landslides, bank erosion and large boulder deposits. 3. At a point that gives **sufficient head** and an easy alignment of the canal to the settling basin. 4. **Upstream of the weir** and next to the undersluice so that the flushing current keeps the intake clear. 5. Away from the confluence of tributaries, with **good access** and space for the gravel trap and settling basin. 6. Where the **river is narrow**, to reduce the length and cost of the weir, and the **flood level** is limited. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Why is the intake important to water quality? A. It sets the turbine speed B. Sediment and trash passing it reach the basin, tunnel and turbines causing abrasion and blockage C. It stores water for peaking D. It generates the head Answer: B. The intake is the link between river and waterway and controls what enters. (Key point: Intake importance) 2. Where on a bend is the intake sited? A. On the outer bank, about 1/3 to 1/2 way along, downstream of the apex B. On the inner bank C. At the bend start on the inner side D. In the middle of the river Answer: A. Helical flow carries bed load away from the opening at the outer bank. (Key point: Bend location) 3. Why locate the intake next to the undersluice? A. To shorten the canal only B. To avoid floods C. The flushing current keeps the intake clear D. To reduce weir height Answer: C. Flushing through the undersluice scours sediment in front of the intake. (Key point: Next to undersluice) 4. What does a poor intake cause? A. Higher net head B. Lower sediment C. Reduced afflux D. Vortices, air entry and heavy losses that cut energy Answer: D. Head loss reduces net head and energy generated. (Key point: Head loss) ## Related in Hydropower Engineering - [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× - [Parts of pressurized and non-pressurized RoR intake](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Aintake-parts-pressurized-nonpressurized-sketch) — Hydropower Engineering, chapter 5 - [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× - [Hydropower intake sketch; minimizing head loss](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Ahydropower-intake-sketch-minimise-headloss) — Hydropower Engineering, chapter 5 - [Optimizing plant capacity of a RoR project](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Aror-optimum-capacity-discussion) — Hydropower Engineering, chapter 3 - [What is an intake? 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