--- title: "Development cycle; RoR layout with headrace canal" subject: "Hydropower Engineering" chapter: 2 key: "semester_7/hydropower_engineering:dev-cycle-ror-layout-headrace-canal" source: https://www.bctengineer.com/q/semester_7/hydropower_engineering/dev-cycle-ror-layout-headrace-canal site: BCT Engineering --- # Development cycle; RoR layout with headrace canal Hydropower Engineering · Chapter 2: Planning of Hydropower Projects - Asked in: 2080 Baishakh, 4+4 marks - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/hydropower_engineering/dev-cycle-ror-layout-headrace-canal - Whole chapter: https://www.bctengineer.com/md/semester_7/hydropower_engineering/chapter-2 ## Question Explain the different phases of the hydropower development cycle. Draw the layout plan and section of a RoR type hydropower project with headrace canal. ## Short answer A RoR plant with headrace canal uses a diversion weir, intake with trash rack, gravel trap, settling basin, contour canal, forebay with spillway and trash rack, penstock, powerhouse, tailrace and switchyard. The canal preserves gross head by a small slope. ## Answer #### Phases of the hydropower development cycle 1. **Reconnaissance:** Desk study and site visit to identify and rank the sites; rough cost and energy. 2. **Pre-feasibility:** Survey, hydrology and geology at a moderate level; compare alternative layouts; select the best. 3. **Feasibility:** Detailed investigation, design optimisation, cost (±10-15%), economic and financial analysis, IEE/EIA. 4. **Detailed design and tendering:** Final drawings, specification, tender documents, contract. 5. **Construction and commissioning:** Build and test the plant. 6. **Operation and maintenance:** Run, maintain and monitor. #### Layout of RoR plant with headrace canal ```text Plan River~~~~~ Weir Canal ~~~~~~~~~~~|Intake=Desander===========\ ~~~~~~~~~~~ \ Forebay \ Penstock PH -> Tailrace -> River Section along waterway weir intake desander canal (slope 1:1000) forebay __|~~~|__ __ ___________________________________| \ penstock \__PH ``` Main components: diversion weir with undersluice, intake with trash rack, gravel trap, settling basin (desander), headrace canal with cross-drainage works, forebay with spillway and trash rack, penstock, powerhouse, tailrace and switchyard. The canal is laid along the contour at a small slope so that most of the gross head is kept for the penstock. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which is a feature of the feasibility stage? A. Desk study only B. Detailed investigation, design optimisation, cost within ±10-15% and IEE/EIA C. Tender and contract signing D. Rough cost and energy estimate Answer: B. Feasibility gives detailed investigation, optimisation, economic and financial analysis and environmental study. (Key point: Feasibility stage content) 2. What is done in the reconnaissance phase? A. Final drawings B. Commissioning of turbines C. Desk study and site visit to identify and rank sites with rough cost and energy D. Detailed drilling at every structure Answer: C. Reconnaissance is a low-cost screening of sites. (Key point: Reconnaissance) 3. Why is the headrace canal laid along the contour at a small slope (about 1:1000)? A. To increase sediment deposition B. So that most of the gross head is kept for the penstock C. To reduce the canal length to zero D. To raise the flow velocity to a maximum Answer: B. A small slope loses little head in the canal, so the head is retained for power. (Key point: Canal slope) 4. What is the correct sequence of the waterway in a RoR plant with headrace canal? A. Weir, intake, desander, canal, forebay, penstock, powerhouse, tailrace B. Weir, penstock, canal, desander, powerhouse C. Intake, forebay, canal, desander, penstock D. Powerhouse, penstock, forebay, canal, weir Answer: A. Water flows from headworks through settling basin and canal to the forebay, then the penstock and powerhouse. 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