Define conveyance of an open channel

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.