Glossary Related to Sediment Transport - Sediment Transport in Irrigation Canals: A New Approach - page 285

Voids Pores or small cavities between the particles in a rock or soil mass, may be

occupied by air, water or both; the spaces between stones or gravel in river
structures.

Volume Control Flow control method with the set point in the middle of the downstream or

upstream canal section.

Wash load Portion of the suspended load with particle sizes smaller than those

found in the bed; in near-permanent suspension and transported without
deposition; the amount of wash load transported through a section is
independent of the transport capacity of the flow.

Washout or washing-out Erosion of earth from canal banks or below structures, caused by excessive

flow velocity and turbulence, accumulation of debris, burrowing animals,
or bad drainage, leading to a complete breakdown of banks, structures, or
lining.

Water-level Elevation of the free water surface relative to a datum; also called stage or

gauge height.

Water-level regulator Structure to regulate the water level.

Water-surface slope Difference in elevation of the water surface per unit horizontal distance in

the flow direction.

Wave amplitudes The magnitude of the greatest departure from equilibrium of the wave

disturbance.

Wave celerity The speed of wave propagation.

Wave frequency The inverse of wave period.

Wave height The vertical distance between the trough and the following crest.

Wave period Time taken for two successive wave crests to pass the same point.

Wavelength The straight-line distance between two successive wave crests.

Weber Moritz Weber (1871-1951) - German Professor.

Weber number Dimension less number characterizing the ratio of inertial forces over

surface tension forces. It is relevant in problems with gas-liquid or

liquid-liquid interfaces.

Wetted perimeter The length of wetted contact between water and the solid boundaries of a

cross-section of an open channel; usually measured in a plane normal to
the flow direction.

Wetted surface The surface area in contact with the flowing water in an open channel.

Width Dimension of a channel measured normal to the flow direction.