---
title: "Alluvial and non-alluvial canals"
subject: "Irrigation and Drainage Engineering"
chapter: 3
key: "semester_6/irrigation_and_drainage_engineering:define-alluvial-nonalluvial-canals"
source: https://www.bctengineer.com/q/semester_6/irrigation_and_drainage_engineering/define-alluvial-nonalluvial-canals
site: BCT Engineering
---

# Alluvial and non-alluvial canals

Irrigation and Drainage Engineering · Chapter 3: Canal Irrigation System

- Asked in: 2079 Asoj, 2 marks; 2073 Magh, 2 marks (asked 2 times)
- Video: [Types of Irrigation channel | Alluvial Channel | Non-Alluvial Channel | Regime Channel | in Hindi](https://www.youtube.com/watch?v=fH6U6t3Yv-o) — Civil Azlan 
- 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/define-alluvial-nonalluvial-canals
- Whole chapter: https://www.bctengineer.com/md/semester_6/irrigation_and_drainage_engineering/chapter-3

## Question

Define alluvial and non-alluvial canals.

## Short answer

Alluvial canals are excavated in loose, erodible alluvial soil; they carry silt and require regime theory (Kennedy/Lacey) for a stable section. Non-alluvial canals are in hard or rocky strata, stable, designed with Manning's or Chezy's formula using permissible velocity, and may be lined.

## Answer

#### Alluvial canals
Canals excavated in **alluvial soil** (deposited by rivers, e.g. the Gangetic and Terai plains), which is fine, loose and easily eroded. The canal carries silt, so the bed and banks can be scoured or silted. The channel must be designed for a stable regime section, using Kennedy's or Lacey's regime theory; the slope and shape adjust themselves until the canal neither silts nor scours.

#### Non-alluvial canals
Canals constructed in **hard soil, rocky terrain or non-erodible strata**, e.g. hilly and peninsular areas, where the bed and banks are stable and the canal does not carry silt that changes its shape. They are designed with Manning's or Chezy's formula using permissible velocity and rugosity, so no regime theory is needed. They may be lined to reduce seepage.

## Check yourself

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

1. How is an alluvial canal defined?
   A. Dug in alluvial soil that is easily eroded, carrying silt, designed by regime theory
   B. Dug in rock, designed with Manning only
   C. Always lined with concrete
   D. Dug only in hills
   Answer: A. Alluvial canals scour or silt, so Kennedy/Lacey regime design is used. (Key point: Alluvial canal)

2. How is a non-alluvial canal designed?
   A. With Lacey's regime theory
   B. With Manning's or Chezy's formula using permissible velocity, no regime theory
   C. With Kennedy's silt theory only
   D. Without any hydraulic design
   Answer: B. Non-erodible hard soil and rock keep the shape stable. (Key point: Non-alluvial canal)

3. Where are non-alluvial canals typically found?
   A. Gangetic and Terai plains
   B. River deltas
   C. Hilly and peninsular areas with hard soil or rock
   D. Flood plains
   Answer: C. Alluvial plains such as the Terai use alluvial canals. (Key point: Setting)