---
title: "Define conveyance of an open channel"
subject: "Hydraulics"
chapter: 5
key: "semester_4/hydraulics:define-conveyance-open-channel"
source: https://www.bctengineer.com/q/semester_4/hydraulics/define-conveyance-open-channel
site: BCT Engineering
---

# Define conveyance of an open channel

Hydraulics · Chapter 5: Basics of Open channel flow

- Asked in: 2082 Kartik, 0.5 marks; 2069 Poush, 1 marks (asked 2 times)
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_4/hydraulics/define-conveyance-open-channel
- Whole chapter: https://www.bctengineer.com/md/semester_4/hydraulics/chapter-5

## Question

Define conveyance of an open channel.

## Short answer

Conveyance K is a measure of carrying capacity, defined by Q = K sqrt(Sf). From Manning, K = (1/n) A R^(2/3). It depends only on geometry and roughness, unit m^3/s, used in compound sections and GVF profiles.

## Answer

**Conveyance** ($K$) of an open channel is a measure of its flow-carrying capacity per unit of the square root of the energy slope. From Manning's equation $Q=\dfrac{1}{n}AR^{2/3}S^{1/2}$:
$$
Q=K\sqrt{S_f},\qquad K=\frac{1}{n}AR^{2/3}
$$
(for Chezy, $K=CAR^{1/2}$). It depends only on the channel geometry (depth, shape and size) and roughness, not on the slope. Its unit is m³/s in SI.

Conveyance is used to compare channel sections, to find the discharge in compound sections (where $K=\sum K_i$), and to compute GVF profiles.

## Check yourself

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

1. Conveyance K is defined by
   A. Q = K Sf
   B. Q = K sqrt(Sf)
   C. Q = K^2 Sf
   D. Q = K/Sf
   Answer: B. It is capacity per unit root of energy slope. (Key point: Definition)

2. In Manning's equation, K equals
   A. (1/n) A R
   B. n A R^(2/3)
   C. A R^(1/2)/n
   D. (1/n) A R^(2/3)
   Answer: D. Chezy gives K = C A R^(1/2). (Key point: Manning form)

3. Conveyance depends on
   A. Bed slope
   B. Geometry and roughness, not slope
   C. Discharge only
   D. Time
   Answer: B. Slope is separated out in Q = K sqrt(Sf). (Key point: Depends on)

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