Coastal Definitions / Advs + Disadvs

Energy Density E

total energy per unit area of sea surface

Group Velocity cg

speed at which energy propagates

Wave Power P

rate of transport of energy

Shoaling

change in shape and behaviour of waves as they propagate into water of decreasing depth

Refraction

bending of a wave as it propagates over different depths

Bathymetric Contours

Contours showing lines along which water depth is the same

Wave Breaking

As waves move into shallower water, they feel the bed more, become less sinusoidal and finally break

Horizontal particle displacement S

The path in coastal waters of a water particle

Inertial force

from the pressure from the movement of the waves, obtained from linear theory

Drag Force

From tangential shear stresses

Interaction Force

Force from water being displaced when waves interact

Reflection Coefficient

Proportion of the wave that is reflected

Factors that influence overtopping

Freeboard, Seaward facing slope, Wave conditions at toe

Armour units

Used as part of coastal defences to dissipate wave energy and they must resist movement

Storm Surge

An elevation in mean water level due primarily to wind in a storm

Wave setup

An elevation in mean water level caused by wave breaking, maximum at the coast

Wave setdown

Diminution in mean water level prior to breaking, maximum at the break point

Beach Nourishment

The placement of large quantities of sand on a beach in order to counteract the effects of erosion

Nourishment Advantage

Aesthetically pleasing

Nourishment Disadvantage

Ongoing cost