Riprap — also known as rip rap, rubble, shot rock or rock armour — is rock or other material used to armor shorelines and streambeds against water erosion.
It is normally made from hard rock, commonly granite, and is used to protect coastlines from erosion and other coastal processes caused by the sea. It is also used inland, on lakes to protect the banks from erosion.
It normally works by absorbing the impact of a wave before the wave reaches the cliff or sea defence, and so minimises the erosion caused by the wave.
It is frequently used to protect the base of old Edwardian/Victorian sea walls, which due to the verticle wall, are often undermined. The rip rap absorbs the impact of the waves if they shoot up the wall, and then fall back down.
- Ciria-CUR (2007) - Rock Manual - The use of rock in hydraulic engineering.
- N.W.H. Allsop (2002) - Breakwaters, coastal structures and coastlines.