RIPRAP - A protective layer or facing of quarrystone randomly placed to 

 prevent erosion, scour, or sloughing of an embankment or bluff toe, also 

 the stone so used, usually well graded within wide size limits. The 

 quarrystone is placed in a layer at least twice the thickness of the 50- 

 percent size stone or 1.25 times the thickness of the largest size stone 

 in the size gradation. 



RUBBLE - (1) Loose angular waterworn stones along a beach. (2) Rough, 

 irregular fragments of broken rock. 



RUBBLE-MOUND STRUCTURE - A mound of random- shaped and random-placed stones 

 protected with a cover layer of selected stones or specially shaped 

 concrete armor units. (Armor units in primary cover layer may be placed 

 in orderly manner or dumped at random.) 



RUNUP - The rush of water up a structure or beach on the breaking of a 

 wave. Also UPRUSH. The amount of runup is the vertical height above 

 Stillwater level that the rush of water reaches. 



SAND - An earthy matrial whose grain size is between 4.76 and 0.075 milli- 

 meters. Within this classification sand may vary from coarse to fine. 

 Sand is cohesionless but exhibits appearance of cohesion when wet. See 

 SOIL CLASSIFICATION. 



SANDCORE JETTY - A jetty, groin or breakwater in which the core material 

 consists of sand rather than stone. 



SARAN - See polyvinyl idene chloride fiber. 



SCREED - A strike board used to level or strike off concrete pavement slabs 

 or cushion courses for block pavements. 



SCOUR - Removal of underwater material by waves and currents, especially 

 at the base or toe of a shore structure. 



SCOUR PROTECTION - The protection at the base or toe of a structure to 

 prevent removal of underwater material by waves and currents. 



SEAWALL,- A structure separating land and water areas, primarily designed 

 to prevent erosion and other damage due to wave action. See also BULK- 

 HEAD. 



SEICHE - (1) A standing wave oscillation of an enclosed water body that 

 continues, pendulum fashion, after the cessation of the originating 

 force, which may have been either seismic or atmospheric. (2) An oscilla- 

 tion of a fluid body in response to a disturbing force having the same 

 frequency as the natural frequency of the fluid system. Tides are now 

 considered to be seiches induced primarily by the periodic forces caused 

 by the sun and moon. (3) In the Great Lakes area, any sudden rise in the 

 water of a harbor or a lake whether or not it is oscillatory. Although 

 inaccurate in a strict sense, this usage is well established in the Great 

 Lakes area. 



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