--- title: "Intake site selection for RoR plant" subject: "Hydro Power" chapter: 5 key: "semester_6/hydro_power:intake-site-selection-ror" source: https://www.bctengineer.com/q/semester_6/hydro_power/intake-site-selection-ror site: BCT Engineering --- # Intake site selection for RoR plant Hydro Power · Chapter 5: Components of Hydropower System - Asked in: 2077 Chaitra, 5 marks - Video: [RoR Headworks Intake Mastery #ror #water #diversion #weir](https://www.youtube.com/watch?v=7NTjkrUl8Bg) — Hydropower - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/hydro_power/intake-site-selection-ror - Whole chapter: https://www.bctengineer.com/md/semester_6/hydro_power/chapter-5 ## Question What factors do you keep in mind while selecting an intake site in a RoR hydropower plant? ## Short answer Select a straight, stable river reach (outer bank if on a bend) with assured dry-season level and minimal sediment. Site needs sound foundation, stable slopes, space for desander, short headrace alignment, construction access, and must avoid GLOF hazards. ## Answer In a run-of-river (RoR) plant there is little or no storage, so the intake must divert the design flow reliably in all seasons while keeping sediment out. The site is chosen by considering the following factors. #### Hydraulic and river factors 1. **Straight, stable reach:** the river should be straight and stable for some distance upstream; if a bend is used, the intake is placed on the **outer (concave) bank**, where secondary currents carry bed load towards the inner bank and clear water flows towards the intake. 2. **Assured water level:** the site must allow the required water level in the dry season, either naturally or with a low weir, so that design flow can always be drawn. 3. **Minimum sediment entry:** avoid reaches with heavy bed load, braided channels or tributary confluences just upstream that bring large sediment. 4. **Narrow river width:** a narrow section with firm banks reduces the length and cost of the weir/diversion structure. 5. **Flood levels:** the intake and its gates must be safe during the design flood; high flood marks should be studied. #### Geological and topographic factors 6. **Sound foundation:** bedrock or a firm foundation at shallow depth for the weir and intake structures. 7. **Stable slopes:** no landslides, debris flows or rock falls on the slopes around the intake. 8. **Space for structures:** enough flat area for the gravel trap, settling basin and approach to the headrace. #### Layout and project factors 9. **Head and alignment:** the site should give the maximum gross head with the shortest and most economical headrace alignment to the forebay/surge tank. 10. **Access and construction:** reasonable road access, space for construction, river diversion during construction. 11. **Environmental and social factors:** downstream release (environmental flow), irrigation rights, fish migration, minimum land acquisition and resettlement. 12. **Ice, debris and glacial hazards:** in Nepal, sites exposed to GLOF and debris flows should be avoided or protected. ```text River bend (plan) ~~~~~~~~~~~~~~~~~~~\ flow -> \ outer bank ~~~~~~~~~~~~~~~~~~\ \ [INTAKE] -> headrace \ \ inner bank (bed \ \ load deposits) \ \ ``` ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. If a bend is used for the intake, it is placed on the: A. Outer (concave) bank B. Centre C. Inner bank D. Any bank Answer: A. Secondary currents carry bed load toward the inner bank, leaving clean water at the outer bank. (Key point: Bend placement) 2. Why must the site ensure a water level in the dry season? A. To increase sediment B. To avoid gates C. So the design flow can always be drawn D. To reduce weir height to zero Answer: C. A run-of-river plant has no storage and relies on assured diversion. (Key point: Dry season water) 3. Why prefer a narrow river section with firm banks? A. Shorter, cheaper weir/diversion structure B. Higher sediment C. Lower head D. Easier flooding Answer: A. Less weir length and cost. (Key point: Narrow river) 4. Which should be avoided upstream of the intake? A. A straight stable reach B. Narrow section C. Braided channels and tributary confluences bringing heavy sediment D. Sound bedrock Answer: C. They bring large sediment into the intake. (Key point: Sediment avoidance) ## Related in Hydro Power - [Gauging site selection and current meter use](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Astream-gauging-site-current-meter) — Hydro Power, chapter 2 - [Firm power and plant load factors](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Afirm-power-load-factors) — Hydro Power, chapter 3 - [Stages of hydropower project study](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Ahydropower-study-stages) — Hydro Power, chapter 3, asked 3× - [Surge tank objectives and economic penstock diameter factors](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Asurge-tank-objectives-economic-diameter) — Hydro Power, chapter 5 ## Related in other subjects - [Hydropower site selection factors](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Asite-selection-discharge-factors) — Power Plant Design, chapter 3 - [Reservoir intake and site selection factors](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Areservoir-intake-site-factors) — Water Supply Engineering, chapter 5, asked 2× - [Common RoR intakes in Nepal; site selection](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Aror-common-intakes-nepal-location) — Hydropower Engineering, chapter 5, asked 2× - [Intake, its functions and site factors](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Aintake-functions-site-factors) — Water Supply Engineering, chapter 5