---
title: "Canal standards and balancing depth"
subject: "Irrigation and Drainage Engineering"
chapter: 3
key: "semester_6/irrigation_and_drainage_engineering:canal-standards-balancing-depth"
source: https://www.bctengineer.com/q/semester_6/irrigation_and_drainage_engineering/canal-standards-balancing-depth
site: BCT Engineering
---

# Canal standards and balancing depth

Irrigation and Drainage Engineering · Chapter 3: Canal Irrigation System

- Asked in: 2073 Bhadra, 2 marks
- Video: [Unit:5 | Balancing a canal Depth| Theory + Numerical | BE Civil | Prashant YT | Irrigation Eng |](https://www.youtube.com/watch?v=e8IvL7ylmI8) — Prashant YT
- 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/canal-standards-balancing-depth
- Whole chapter: https://www.bctengineer.com/md/semester_6/irrigation_and_drainage_engineering/chapter-3

## Question

Write about canal standards and balancing depth.

## Short answer

Canal standards define design values for side slopes, freeboard, berm width, bank top width, bed width-depth ratio, permissible velocity, curve radius, and hydraulic gradient to ensure safety and economy. Balancing depth is the bed depth below ground where excavation equals fill for banks, eliminating borrow pits and spoil banks for minimum cost.

## Answer

**Canal standards** are the standard design values adopted for canal sections, so that canals are safe and economical: side slopes (1.5:1 in cutting, 2:1 in filling in the usual case), free board (0.5-1 m by discharge), berm width, bank top width (1.5-6 m, wider for service roads), bed width to depth ratio, permissible velocity and bed slope, curve radius, and the hydraulic gradient inside the bank.

**Balancing depth** is the depth of canal bed below ground at which the earth excavated equals the earth required for the banks. Then there is neither a borrow pit nor a spoil bank, so cost is least. It is found from $(B+n_1d)d = $ area of filling in banks.

## Check yourself

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

1. What are canal standards?
   A. Standard design values such as side slopes, free board, berm and bank top width
   B. Names of canal types
   C. Soil classes
   D. Irrigation intensities
   Answer: A. They make canals safe and economical. (Key point: Canal standards)

2. What happens at balancing depth?
   A. Banks are zero
   B. Excavated earth equals bank requirement, so no borrow pit or spoil bank
   C. The canal is lined
   D. Free board is zero
   Answer: B. Cost is least. (Key point: Balancing depth)

3. What typical side slopes are standard?
   A. 2:1 in cutting and 1.5:1 in filling
   B. 1:1 both
   C. 1.5:1 in cutting and 2:1 in filling
   D. 3:1 both
   Answer: C. Made-up soil is placed flatter. (Key point: Typical slopes)

## Related in Irrigation and Drainage Engineering

- [Derive the balancing depth of a canal](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Abalancing-depth-derive) — Irrigation and Drainage Engineering, chapter 3, asked 2×
- [Balancing depth and canal cross-section](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Abalancing-depth-bed8-section) — Irrigation and Drainage Engineering, chapter 3
- [Balancing depth: bed width 20 m](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Abalancing-depth-bed20-cut15-fill2) — Irrigation and Drainage Engineering, chapter 3, asked 3×
- [Balancing depth: bed width 25 m](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Abalancing-depth-bed25) — Irrigation and Drainage Engineering, chapter 3, asked 3×
- [Balancing depth with service bank and free board](https://www.bctengineer.com/question.md?key=semester_6%2Firrigation_and_drainage_engineering%3Abalancing-depth-bed8-service-bank) — Irrigation and Drainage Engineering, chapter 3