---
title: "Key differences between weir and barrage"
subject: "Irrigation and Drainage Engineering"
chapter: 5
key: "semester_6/irrigation_and_drainage_engineering:weir-vs-barrage-differences"
source: https://www.bctengineer.com/q/semester_6/irrigation_and_drainage_engineering/weir-vs-barrage-differences
site: BCT Engineering
---

# Key differences between weir and barrage

Irrigation and Drainage Engineering · Chapter 5: Diversion Headworks

- Asked in: 2080 Chaitra, 3 marks
- Video: [Irrigation: Difference Between Weir and Barrage](https://www.youtube.com/watch?v=F-VZQnHeiLE) — 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/weir-vs-barrage-differences
- Whole chapter: https://www.bctengineer.com/md/semester_6/irrigation_and_drainage_engineering/chapter-5

## Question

Discuss key differences between weir and barrage.

## Short answer

A weir has a raised crest with limited gate control, high afflux, low cost, and is suited for rocky rivers. A barrage has a low crest with many gates, better water level and silt control, small afflux, and higher cost, suited for alluvial plains with large discharge.

## Answer

| Point | Weir | Barrage |
|---|---|---|
| Ponding | By raising the crest (solid, with shutters on top) | By gates; the crest is at low level |
| Control of water level | Limited; pond level is mostly fixed | Good; gates control the level and the flood passage |
| Gates | Few or none (shutters) | Many gates across the full width |
| Afflux in floods | Large | Small, because gates are opened |
| Cost | Low | High |
| Silt control | Poor | Better (scouring by gates) |
| Suitable for | Rocky or hilly rivers, small discharges | Alluvial plains, large rivers, high discharge |
| Foundation | Rock or sand, with piles | Usually sand; heavier floor and piles |
| Maintenance | Easy | More complex (gate machinery) |

## Check yourself

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

1. How is ponding done in a weir versus a barrage?
   A. Weir by raising the solid crest; barrage by gates with a low crest
   B. Both by gates
   C. Weir by gates; barrage by solid crest
   D. Neither raises the pond
   Answer: A. A weir ponds by crest (with shutters); a barrage by gates. (Key point: Ponding)

2. Which has smaller afflux in floods?
   A. Weir
   B. Barrage, since gates are opened
   C. Both equal
   D. Neither
   Answer: B. Gates are opened in floods, reducing afflux. (Key point: Afflux)

3. Which is suited to alluvial plains and large rivers?
   A. Weir
   B. Neither
   C. Barrage
   D. Both equally
   Answer: C. Barrages suit alluvial plains with large discharge; weirs suit rocky or hilly rivers. (Key point: Suitability)

## Related in Irrigation and Drainage Engineering

- [Khosla: barrage HGL and floor thickness](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Akhosla-barrage-hgl-thickness-pond1135) — Irrigation and Drainage Engineering, chapter 5
- [Diversion weir: Bligh and Khosla, 4000 m3/s](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Adiversion-weir-bligh-khosla-q4000) — Irrigation and Drainage Engineering, chapter 5

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