--- title: "Remedial measures for sediment deposition in RoR" subject: "Hydropower Engineering" chapter: 5 key: "semester_7/hydropower_engineering:ror-sediment-deposition-remedial-measures" source: https://www.bctengineer.com/q/semester_7/hydropower_engineering/ror-sediment-deposition-remedial-measures site: BCT Engineering --- # Remedial measures for sediment deposition in RoR Hydropower Engineering · Chapter 5: Headworks of Run-of- River (RoR) Plants - Asked in: 2076 Ashwin, 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/ror-sediment-deposition-remedial-measures - Whole chapter: https://www.bctengineer.com/md/semester_7/hydropower_engineering/chapter-5 ## Question Explain various remedial measures that help to control the deposition of sediments in a RoR project. ## Short answer Deposition is controlled by placing intake on outer bend with sill above bed, using an undersluice/flushing gate, a divide wall to skim cleaner water, gravel trap and settling basin with flushing. Also shut intake during flood peaks, lower pond for drawdown flushing, catchment treatment, and regular dredging. ## Answer Sediment deposition in a RoR project occurs at the intake, in the gravel trap, in the settling basin, in the headrace and in front of the weir. It is controlled by the following measures. 1. **Choice of the intake location**: place the intake on the outer bank of a river bend with the sill above the river bed, so that the bed load moves past it. 2. **Undersluice (scouring sluice) and flushing gates** in front of the intake, which are opened during floods to flush the deposited sediment past the weir. 3. **Divide wall and curtain (skimming) wall** to draw only the upper, cleaner layer of water into the intake. 4. **Gravel trap** after the intake to settle the coarse material, with a flushing gate. 5. **Settling basin (desander)** large enough to settle particles above the design size (0.15-0.2 mm), with a flushing system (intermittent or continuous). 6. **Flood operation rule**: shut the intake during the high sediment load of the flood season, or when the concentration exceeds the limit. 7. **Weir pond operation**: lower the pond level for sluicing during floods (drawdown flushing) so that the sediment is pushed out. 8. **Catchment treatment** (afforestation, check dams, terracing, bank protection) to reduce sediment production. 9. **Regular maintenance**: dredging and cleaning of the canal and the pond. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Where should a RoR intake be located to limit bed-load entry? A. On the inner bank of a bend at river bed level B. On the outer bank of a bend with the sill above the bed C. In the middle of a straight reach at bed level D. Downstream of the settling basin Answer: B. The outer bank of a bend with a raised sill lets bed load move past instead of entering. (Key point: Intake location) 2. What is the purpose of the undersluice (scouring sluice) in front of the intake? A. To store water for peak power B. To flush deposited sediment through the weir when opened in floods C. To measure discharge D. To increase the head Answer: B. Opening the undersluice in floods sweeps sediment accumulated in front of the intake past the weir. (Key point: Undersluice) 3. What does a divide wall and curtain (skimming) wall do? A. Draws only the upper cleaner layer of water into the intake B. Draws bottom water rich in bed load C. Reduces the weir length D. Increases the settling velocity Answer: A. Sediment concentration is higher near the bed, so taking the upper layer keeps coarse material out. (Key point: Skimming wall) 4. What is the flood operation rule? A. Keep the intake fully open to maximise energy B. Shut the intake when sediment concentration is high in floods or crosses the limit C. Raise the weir crest during floods D. Increase turbine speed Answer: B. Closing the intake in high sediment periods protects the basin and turbines. (Key point: Flood operation rule) ## Related in Hydropower Engineering - [Sediment deposition in storage reservoir; management](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Astorage-sediment-deposition-management) — Hydropower Engineering, chapter 4 - [Sediment yield, reservoir life and remedies](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Areservoir-sedimentation-yield-life-remedies) — Hydropower Engineering, chapter 4 - [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 - [Seepage control measures in embankment dam](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Aembankment-seepage-control-measures) — Hydropower Engineering, chapter 4 - [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× - [Working principle of RoR, PRoR and ST plants](https://www.bctengineer.com/question.md?key=semester_7%2Fhydropower_engineering%3Aror-pror-storage-working-principle) — Hydropower Engineering, chapter 2 ## Related in other subjects - [Remedial measures for slope failure](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Aslope-remedial-measures) — Soil Mechanics, chapter 11 - [In-plane, out-of-plane failure and remedial measures](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Ain-plane-out-of-plane-remedial) — Concrete Technology and Masonry Structure, chapter 9 - [Project selection with high sediment rivers](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aproject-selection-sediments) — Power Plant Design, chapter 3 - [Silt excluder, silt ejector, sediment control](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Asilt-excluder-ejector-sediment-control) — Irrigation and Drainage Engineering, chapter 5, asked 10×