Permeable - Having openings large enough to permit free passage of appreciable quantities of (1) sand or (2)
water.
Pile - Long, heavy section of timber, concrete or metal driven or jetted into the earth or seabed as support or
protection.
Pile, Sheet - Pile with a generally slender, flat cross section driven into the ground or seabed and meshed or
interlocked with like members to form a diaphragm, wall, or bulkhead.
Piling - Group of piles.
Plug - Core containing both plants and underlying soil, usually cut with a cylindrical coring device and
transplanted to a hole cut by the same device.
Polyvinyl Chloride (PVC) - Plastic material (usually black) that forms a resilient coating suitable for protecting
metal from corrosion.
Profile, Beach - Intersection of the ground surface with a vertical plane that may extend from the top of the dune
line to the seaward limit of sand movement.
PVC - See POLYVINYL CHLORIDE.
Ravelling - Progressive deterioration of a revetment under wave action.
Refraction (of water waves) - (1) Process by which direction of a wave moving in shallow water at an angle to
the contours is changed. Part of the wave advancing in shallower water moves more slowly than the part still
advancing in deeper water, causing the wave crest to bend toward alignment with the underwater contours. (2)
Bending of wave crests by currents.
Revetment - Facing of stone, concrete, etc., built to protect a scarp, embankment, or shore structure against
erosion by waves or currents.
Rhizome - Underground stem or root stock. New shoots are usually produced from the tip of the rhizome.
Riprap - Layer, facing, or protective mound of stones randomly placed to prevent erosion, scour, or sloughing of
a structure or embankment; also, the stone so used.
Rubble - (1) Loose, angular, waterworn stones along a beach. (2) Rough, irregular fragments of broken rock or
concrete.
Runup - The rush of water up a structure or beach on breaking of a wave. Amount of runup is the
vertical height above stillwater level that the rush of water reaches.
Sand - Generally, coarse-grained soils having particle diameters between 0.18 and approximately 0.003 inches.
Sands are intermediate between SILT and GRAVEL.
Sandbag - Cloth bag filled with sand or grout and used as a module in a shore protection device.
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