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Breakwaters
A breakwater is a permanent structure constructed at a coastal area to protect against tides, currents, waves, and storm surges. Breakwaters have been built since antiquity to protect anchorages, helping isolate vessels from marine hazards such as wind-driven waves. A breakwater, also known in some contexts as a jetty or a mole, may be connected to land or freestanding, and may contain a walkway or road for vehicle access. Part of a coastal management system, breakwaters are installed parallel to the shore to minimize erosion. On beaches where longshore drift threatens the erosion of beach material, smaller structures on the beach may be installed, usually perpendicular to the water's edge. Their action on waves and current is intended to slow the longshore drift and discourage mobilisation of beach material. In this usage they are more usually referred to as groynes. Purposes Breakwaters reduce the intensity of wave action in inshore waters and thereby provide safe har ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rock Armour
Riprap (in North American English), also known as rip rap, rip-rap, shot rock, rock armour (in British English) or rubble, is human-placed rock or other material used to protect shoreline structures against scour and water, wave, or ice erosion. Riprap is used to armor shorelines, streambeds, bridge abutments, foundational infrastructure supports and other shoreline structures against erosion. Common rock types used include granite and modular concrete blocks. Rubble from building and paving demolition is sometimes used, as well as specifically designed structures called ''tetrapods'' or similar concrete blocks. Riprap is also used underwater to cap immersed tubes sunken on the seabed to be joined into an undersea tunnel. Environmental effects Sediment effects Riprap causes morphological changes in the riverbeds they surround. One such change is the reduction of sediment settlement in the river channel, which can lead to scouring of the river bed as well as coarser sedime ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mole (architecture)
A mole is a massive structure, usually of stone, used as a pier, breakwater, or a causeway separating two bodies of water. A mole may have a wooden structure built on top of it that resembles a wooden pier. The defining feature of a mole, however, is that water cannot freely flow underneath it, unlike a true pier. The oldest known mole is at Wadi al-Jarf, an ancient Egyptian harbor complex on the Red Sea, constructed . The word comes from Middle French ''mole'', ultimately from Latin ''mōlēs'', meaning a large mass, especially of rock; it has the same root as molecule and mole, the chemical unit of measurement. Heptastadion Notable in antiquity was the Heptastadion, a giant mole built in the 3rd century BC in the city of Alexandria, Egypt to join the city to ''Pharos Island'' where the Pharos lighthouse stood. The causeway formed a barrier separating Alexandria's oceanfront into two distinct harbours, an arrangement which had the advantage of protecting the harbours fro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wave Overtopping
Wave overtopping is the time-averaged amount of water that is discharged (in liters per second) per structure length (in meters) by wind waves, waves over a structure such as a breakwater (structure), breakwater, revetment or levee, dike which has a crest height above still water level. When waves break over a dike, it causes water to flow onto the land behind it. Excessive overtopping is undesirable because it can compromise the integrity of the structure or result in a safety hazard, particularly when the structure is in an area where people, infrastructure or vehicles are present, such as in the case of a dike fronting an esplanade or densely populated area. Wave overtopping typically transpires during extreme weather events, such as intense storms, which often elevate water levels beyond average due to wind setup. These effects may be further intensified when the storm coincides with a high spring tide. Excessive overtopping may cause damage to the inner slope of the di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
