---
title: "Project selection with high sediment rivers"
subject: "Power Plant Design"
chapter: 3
key: "semester_8/power_plant_design:project-selection-sediments"
source: https://www.bctengineer.com/q/semester_8/power_plant_design/project-selection-sediments
site: BCT Engineering
---

# Project selection with high sediment rivers

Power Plant Design · Chapter 3: Hydro Power Plant Design

- Asked in: 2070 Magh, 5+3 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_8/power_plant_design/project-selection-sediments
- Whole chapter: https://www.bctengineer.com/md/semester_8/power_plant_design/chapter-3

## Question

What are the criteria for selection of a hydropower project? If the water in the river is known to carry high sediments and debris, what would be your particular recommendation in its design?

## Short answer

Project selection criteria: hydrology, head, topography/geology, sediment load, access/transmission, environmental/social impact, power market, economics, legal. For high sediment, use gated weir with undersluice and debris barrier, side intake on outer bend with raised sill and sediment excluder, gravel trap, large desander, Pelton or sediment-resistant Francis with hard coatings, and shutdown during high sediment peaks.

## Answer

#### Criteria for selection of a hydropower project
1. **Hydrology:** sufficient and reliable flow; FDC and long-term data.
2. **Head:** steep gradient or large drop over a short distance.
3. **Topography and geology:** good dam, tunnel and powerhouse sites; stable slopes.
4. **Sediment and hazards:** sediment load, floods, GLOF, landslides and seismicity.
5. **Access and transmission:** road access and distance to grid or load centre.
6. **Environmental and social impact:** submergence, resettlement, fish, protected areas; EIA clearance.
7. **Power market:** demand, PPA possibility and energy mix (peaking or base load).
8. **Economics:** cost per kW, levelised cost per kWh, IRR, B/C ratio, payback.
9. **Legal and institutional:** licences, water rights and local acceptance.

#### Recommendation for a river with high sediment and debris
1. **Headworks:** gated weir with **undersluice** to keep the intake area flushed; **boulder/debris barrier** and coarse trash rack upstream of intake.
2. **Intake design:** side intake placed on the outer bend, raised sill and **sediment excluder** to draw cleaner surface water.
3. **Gravel trap** close to the intake with flushing gates.
4. **Larger desander:** multiple bays, designed to remove finer particles (e.g. 0.2 mm, or 0.1–0.15 mm for high-head Pelton/Francis), with continuous or frequent flushing.
5. **Turbine choice:** prefer **Pelton** where head allows, as it is easier to repair; for Francis, use lower runner velocity and sediment-resistant design.
6. **Materials:** 13Cr-4Ni stainless steel runners with hard coatings (e.g. tungsten-carbide HVOF) on runners, guide vanes and nozzles.
7. **Operation:** monitor sediment concentration online and shut down units during flood peaks above a set limit; keep spare runners and needles.
8. **For storage/pondage:** provide low-level flushing outlets and plan regular reservoir flushing.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which is among the criteria for selecting a hydropower project?
   A. Hydrology, head, geology, sediment and hazards, economics, environment, power market
   B. Only the project name
   C. Only the length of the road
   D. Only the number of villagers
   Answer: A. Selection considers technical, environmental, market, economic and legal factors. (Key point: Project selection criteria)

2. For a river with high sediment and debris, which headworks feature is recommended?
   A. Intake in the middle of a still pool
   B. No trash rack
   C. Gated weir with undersluice, debris barrier, side intake on outer bend with sediment excluder
   D. A very low intake sill
   Answer: C. Undersluice keeps the intake flushed; the outer bend, raised sill and excluder draw cleaner surface water. (Key point: Headworks for high sediment)

3. For high sediment, the design should provide:
   A. A smaller desander and Francis turbine only
   B. A larger multi-bay desander with frequent flushing, Pelton where head allows, and hard-coated 13Cr-4Ni runners
   C. No desander because the turbine is hard
   D. Plain mild steel runners
   Answer: B. Better settling plus erosion-resistant turbine and materials limit sediment wear. (Key point: Desander and turbine)

## Related in Power Plant Design

- [High dam hydropower project components](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Ahigh-dam-components) — Power Plant Design, chapter 3
- [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
- [Criteria for turbine selection](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aturbine-selection-criteria) — Power Plant Design, chapter 3, asked 3×
- [Daily pondage run-of-river components](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Adaily-pondage-ror-components) — Power Plant Design, chapter 3
- [ROR versus PROR hydropower plants](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aror-vs-pror) — Power Plant Design, chapter 3
- [Steps to build a hydro project and sell to NEA](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Ahydro-project-steps-nea) — Power Plant Design, chapter 3, asked 4×

## Related in other subjects

- [Hydropower project recommendation to government](https://www.bctengineer.com/question.md?key=semester_6%2Fengineering_economics%3Ahydropower-multipurpose-bcr-60yr) — Engineering Economics, chapter 3
- [Final project report: title page, abstract, recommendation](https://www.bctengineer.com/question.md?key=semester_5%2Fcommunication_english%3Afinal-report-title-abstract-recommendation) — Communication English, chapter 8
- [General river intake and site selection](https://www.bctengineer.com/question.md?key=semester_5%2Fwater_supply_engineering%3Ageneral-river-intake) — Water Supply Engineering, chapter 5, asked 3×
- [Quartz significance for hydropower project](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Aquartz-hydropower-significance) — Engineering Geology II, chapter 1