---
title: "RT works, methods and guide bank components"
subject: "Irrigation and Drainage Engineering"
chapter: 6
key: "semester_6/irrigation_and_drainage_engineering:river-training-guide-bank-components-62b"
source: https://www.bctengineer.com/q/semester_6/irrigation_and_drainage_engineering/river-training-guide-bank-components-62b
site: BCT Engineering
---

# RT works, methods and guide bank components

Irrigation and Drainage Engineering · Chapter 6: River Training Works

- Asked in: 2062 Baisakh (old course), 1+2+5 marks
- Video: [Irrigation- River training works / Objectives / Classification / Methods of River training (Hindi)](https://www.youtube.com/watch?v=RUyHrZIB1WU) — Yogendra Ram Meena
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/irrigation_and_drainage_engineering/river-training-guide-bank-components-62b
- Whole chapter: https://www.bctengineer.com/md/semester_6/irrigation_and_drainage_engineering/chapter-6

## Question

Define river training works. Enumerate different methods of river training works. Explain the design of different components of a guide bank.

## Answer

#### Definition (1 mark)
**River training works** are structures built on or along a river to guide the flow, stabilise its course, protect its banks and safeguard structures like bridges and barrages from floods and erosion.

#### Methods (2 marks)
1. Guide bunds (guide banks).
2. Spurs (groynes).
3. Marginal embankments (levees).
4. Bank pitching (revetment) with a launching apron.
5. Cut-offs.
6. Bed sills, check dams and bio-engineering.

#### Design of the components of a guide bank (5 marks)
Waterway: Lacey's regime width $W = 4.75\sqrt{Q}$ (Q in m³/s). Silt factor $f = 1.76\sqrt{d_{mm}}$.

| Component | Design |
|---|---|
| Length of guide bank | Upstream shank $1.0$ to $1.5W$; downstream tail $0.2$ to $0.5W$ |
| Curved head | Radius about $0.5W$ (upstream), sweep $120$ to $145^\circ$; downstream sweep about $45^\circ$ |
| Top level and width | HFL $+ 1.5$ m free-board; width 6 m (3 to 6 m) |
| Side slopes | 2:1 river side (3:1 around the head); 2:1 country side |
| Pitching | Thickness $t = 0.06Q^{1/3}$ on 0.15 to 0.3 m graded filter |
| Scour depth | $R = 0.47(Q/f)^{1/3}$; $2R$ below HFL at nose, $1.5R$ at shank |
| Launching apron | Depth below bed $D' = $ scour depth $-$ flood depth; width $1.5D'$; launched thickness $1.5t$ (laid about $2.25t$) |

```text
 Section at shank
      _6 m_
     /     \  HFL+1.5 m
 HFL/_______\ 2:1
   / pitching \
 _/___filter___\_ apron (width 1.5D', launches at 2:1)
```
The apron is laid at the toe of the pitching and, as the river scours the bed, the stones slide down the 2:1 slope and protect the bund against undermining.

## Check yourself

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

1. River training works are:
   A. Canal linings
   B. Water supply pipelines
   C. Power houses
   D. Structures that guide flow, stabilise the course, protect banks and safeguard bridges and barrages
   Answer: D. They protect structures from floods and erosion by stabilising the river. (Key point: Definition)

2. Which is correct for the guide bank plan?
   A. Head sweep 20 degrees
   B. Upstream shank 1-1.5W, tail 0.2-0.5W, head radius about 0.5W with sweep 120-145 degrees
   C. Tail 5W
   D. Shank 0.1W
   Answer: B. These are the standard plan proportions based on Lacey's waterway. (Key point: Length and head)

3. Top level, width and slopes of the guide bank?
   A. HFL - 1.5 m, width 1 m
   B. HFL + 1.5 m, width 6 m (3-6), 2:1 river side (3:1 at head)
   C. Slopes 10:1
   D. HFL, width 20 m
   Answer: B. Free-board of 1.5 m and flat slopes at the head give stability. (Key point: Top and slopes)

4. Pitching thickness and scour depth formulas?
   A. t = 0.06 Q^(1/3); R = 0.47 (Q/f)^(1/3), 2R at nose and 1.5R at shank
   B. t = 0.47 Q; R = 0.06 Q
   C. R = f/Q
   D. t = 4.75 sqrt(Q)
   Answer: A. These are the standard Lacey-based design relations. (Key point: Pitching and scour)

5. What does the launching apron do?
   A. Provides filter
   B. As the bed scours, stones slide down the 2:1 slope protecting the bund from undermining
   C. Carries traffic
   D. Raises the top of bund
   Answer: B. D' = scour - flood depth, width 1.5D', launched thickness 1.5t. (Key point: Launching apron)

## Related in Irrigation and Drainage Engineering

- [Objectives of river training works](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Ariver-training-objectives-five) — Irrigation and Drainage Engineering, chapter 6
- [Guide bank design, 4000 m3/s, d 0.40 mm](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Aguide-bank-q4000-hfl205-bed202) — Irrigation and Drainage Engineering, chapter 6
- [Guide bank design, 6500 m3/s](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Aguide-bank-bed105-depth5-q6500) — Irrigation and Drainage Engineering, chapter 6
- [Define RT works, objectives, purposes of spur](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Ariver-training-objectives-spur-purposes) — Irrigation and Drainage Engineering, chapter 6
- [Objectives of RT works and spur spacing](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Ariver-training-objectives-spur-spacing) — Irrigation and Drainage Engineering, chapter 6
- [RT works for a bridge; launching apron](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Ariver-training-bridge-launching-apron) — Irrigation and Drainage Engineering, chapter 6

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