Riprap (in

North American English North American English (NAmE, NAE) is the most generalized variety of the English language as spoken in the United States and Canada. Because of their related histories and cultures, plus the similarities between the pronunciations (accents), ...

), also known as rip rap, rip-rap, shot rock, rock armour (in

British English British English (BrE, en-GB, or BE) is, according to Oxford Dictionaries, "English as used in Great Britain, as distinct from that used elsewhere". More narrowly, it can refer specifically to the English language in England, or, more broadl ...

) or rubble, is human-placed rock or other material used to protect shoreline structures against

scour Scour may refer to: Hydrodynamic processes * Hydrodynamic scour, the removal of sediment such as sand and silt from around an object * Bridge scour, erosion of soil around at the base of a bridge pier or abutments via the flow of air, ice, or ...

and water, wave, or ice erosion. Ripraps are used to

armor Armour (British English) or armor (American English; see spelling differences) is a covering used to protect an object, individual, or vehicle from physical injury or damage, especially direct contact weapons or projectiles during combat, or f ...

shore A shore or a shoreline is the fringe of land at the edge of a large body of water, such as an ocean, sea, or lake. In physical oceanography, a shore is the wider fringe that is geologically modified by the action of the body of water past a ...

lines, streambeds, bridge

abutments An abutment is the substructure at the ends of a bridge span or dam supporting its superstructure. Single-span bridges have abutments at each end which provide vertical and lateral support for the span, as well as acting as retaining wal ...

, foundational infrastructure supports and other shoreline structures against erosion. Common rock types used include

granite Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies un ...

and modular

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...

blocks.

Rubble Rubble is broken stone, of irregular size, shape and texture; undressed especially as a filling-in. Rubble naturally found in the soil is known also as 'brash' (compare cornbrash)."Rubble" def. 2., "Brash n. 2. def. 1. ''Oxford English Dictionar ...

from building and paving demolition is sometimes used, as well as specifically designed structures called

tetrapods Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids (reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct therapsi ...

Riprap is also used underwater to cap immersed tubes sunken on the seabed to be joined into an undersea tunnel.

Environmental effects

Sediment effects

Ripraps cause 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 sediment particles. This can be combatted by increasing the distance between the pieces of riprap and using a variety of sizes. The usage of ripraps may not even stop erosion, but simply move it downstream. Additionally, the soil beneath the riprap can be eroded if the rock was just placed on top without any buffer between the layers such as a

geotextile Geotextiles are permeable fabrics which, when used in association with soil, have the ability to separate, filter, reinforce, protect, or drain. Typically made from polypropylene or polyester, geotextile fabrics come in two basic forms: woven (r ...

fabric or smaller riprap (

crushed stone Crushed stone or angular rock is a form of construction aggregate, typically produced by mining a suitable rock deposit and breaking the removed rock down to the desired size using crushers. It is distinct from naturally occurring gravel, which ...

Changes in organic material and the ecosystem

Riprap affects the amount of organic material in a waterbody by acting as a filter, catching wood and leaves before they can enter the water. Riprap also covers and prevents plants from growing through, which can reduce shade over the water. Introducing ripraps creates a rocky environment which can affect the

ecology Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overl ...

of a waterbody by making the ecosystem more heterogeneous. While it can negatively affect some

organisms In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells ( cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and fu ...

by removing shoreline vegetation, the rock can provide important refuge for

invertebrates Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordat ...

and small

fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...

. By preventing woody plants from growing and shading the water, riprap can also increase the amount of

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...

and

hydrophytes Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that g ...

Gallery

File:11-8-07 riprap photo.jpg,

Concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...

rubble used as riprap along the

San Francisco Bay San Francisco Bay is a large tidal estuary in the U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the big cities of San Francisco, San Jose, and Oakland. San Francisco Bay drains water f ...

shoreline File:Sea defences - geograph.org.uk - 775461.jpg, Modular concrete block riprap File:Access to Beach is Blocked - geograph.org.uk - 1107949.jpg, Modular concrete block riprap File:Cape Hinomisaki Izumo04bs3200.jpg, Modular concrete block riprap File:Riprap.jpg, Riprap lining a lake shore File:Construction of river channel closing structure in the Mississippi NRRA (7df8f79e-1761-4967-a358-64b4e9a4d1c3).jpg, Riprap closing off a channel on the

Mississippi River The Mississippi River is the List of longest rivers of the United States (by main stem), second-longest river and chief river of the second-largest Drainage system (geomorphology), drainage system in North America, second only to the Hudson B ...

File:Corps completes Yolo Bypass levee repairs (6792076725).jpg, Riprap protecting a

levee A levee (), dike (American English), dyke (Commonwealth English), embankment, floodbank, or stop bank is a structure that is usually earthen and that often runs parallel to the course of a river in its floodplain or along low-lying coastli ...

File:Crews replacing riprap at Seawall.jpg, Crews replacing riprap at

Galveston Galveston ( ) is a coastal resort city and port off the Southeast Texas coast on Galveston Island and Pelican Island in the U.S. state of Texas. The community of , with a population of 47,743 in 2010, is the county seat of surrounding Ga ...

Seawall after a 1915 hurricane File:Dawlish Warren , Rip Rap and Coastal Scenery - geograph.org.uk - 1345833.jpg, Riprap protecting a concrete retaining wall

References

* Ciria-CUR (2007)
Rock Manual - The use of rock in hydraulic engineering
* N.W.H. Allsop (2002)
Breakwaters, coastal structures and coastlines
*US Dept. of Transportation (2004)

External links

Ohio Dept. of Natural Resources riprap guideUS Bureau of Reclamation publication on riprap for dam overtoppingUSGS Minerals Yearbook: Stone, Crushed
{{geotechnical engineering Building stone Types of wall Earthworks (engineering) Coastal construction