Glossary Related to Sediment Transport - Sediment Transport in Irrigation Canals: A New Approach - page 281

Regression analysis Statistical technique applied to paired data to determine the degree or

intensity of mutual association of a dependent variable with one or more
independent variables.

Regular waves Waves with a single height, period and direction.

Regulator Structure to set (regulate) water levels and/or discharges in an irrigation

network.

Relative density Density of soil material with reference to its maximum possible density

for a given compaction effort. Can be expressed as a percentage of the
maximum possible density, or using descriptive terms such as 'loose',
'medium' or 'dense'.

Response time Time-lag, i.e. The time needed for a canal network to reach a new steady

state after a change in water level or discharge.

Reynolds Osborne Reynolds (1842-1912) - British physicist and mathematician who

expressed the Reynolds number and stress (i.e. turbulent shear stress).

Reynolds number Dimensionless num b er representing the ratio of the inertia force over the

viscous force: Re = vD/ν .

Roughness coefficient Factor in formulae for computing the average flow velocity in open channels

that represents the effect of roughness and other geometric characteristics
of the channel upon the energy losses; e.g. the de Chézy, Manning or
Strickler coefficients.

Roughness factor See roughness coefficient.

Saltation In sediment transport, particle motion by jumping and bouncing along

the bed.

Sand Sediment particles, mainly quartz, with a diameter of between 0.062 mm

and 2 mm, generally classified as fine, medium, coarse or very coarse.

Sand trap Enlargement in a channel where the velocity drops so that any sand that it

carries can settle and be removed.

Scalar A quantity that has a magnitude described by a real number and no

direction. A scalar means a real number rather than a vector.

Scour Removal of bed material by the eroding power of a flow of water; erosive

action, particularly, pronounced local erosion by fast flowing water that
excavates and carries away material from the bed and banks.

Sediment Any material carried in suspension by the flow or as bed load that would

settle to the bottom in the absence of fluid motion; particles transported
by, suspended in or deposited by a flow.

Sediment concentration The ratio of the mass (or volume) of the dry sediment in a water/sediment

mixture to the total mass (or volume) of the suspension.

Sediment load The amount of sediment carried/transported by running water.

Sediment transport Movement of sediment transported in any way by a flow; from the point

of transport it is the sum of suspended and bed load transported; from the
point of origin it is the sum of bed material load and the wash load.

Sediment transport
capacity

Ability of a stream to carry a certain volume of sediment per unit time for
given flow conditions. Also called the sediment transport potential.