Datum, Vertical

– A vertical datum is a permanent elevation for a location in space used as an elevation to which other elevations are referred. Tidal datums are one type of vertical datum that relate elevations to the approximate land-water intersection at a particular location (such as a tide station). Orthometric datums are another type of vertical datum that use global mean sea level to approximate a land-based plane of zero elevation from which to reference other measured elevations.

Design Life

– The forecast life expectancy of infrastructure based on its design.

Diurnal Tide –

A tide cycle with one high tide and one low tide each day.

Diffraction, Wave –

The process of waves changing direction (bending or wrapping) as they encounter an obstacle, structure, or narrow opening. This is a nearshore process.