Armor, in hydrology

Hydrology

Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...

 and geography

Geography

Geography is the science that studies the lands, features, inhabitants, and phenomena of Earth. A literal translation would be "to describe or write about the Earth". The first person to use the word "geography" was Eratosthenes...

 is the association of surface pebble

Pebble

A pebble is a clast of rock with a particle size of 4 to 64 millimetres based on the Krumbein phi scale of sedimentology. Pebbles are generally considered to be larger than granules and smaller than cobbles . A rock made predominantly of pebbles is termed a conglomerate...

s, rocks or boulder

Boulder

In geology, a boulder is a rock with grain size of usually no less than 256 mm diameter. While a boulder may be small enough to move or roll manually, others are extremely massive....

s with stream bed

Stream bed

A stream bed is the channel bottom of a stream, river or creek; the physical confine of the normal water flow. The lateral confines or channel margins, during all but flood stage, are known as the stream banks or river banks. In fact, a flood occurs when a stream overflows its banks and flows onto...

s or beach

Beach

A beach is a geological landform along the shoreline of an ocean, sea, lake or river. It usually consists of loose particles which are often composed of rock, such as sand, gravel, shingle, pebbles or cobblestones...

es. Most commonly hydrological

Hydrology

Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...

 armor occurs naturally; however, a man-made form is usually called riprap

Riprap

Riprap — also known as rip rap, rubble, shot rock or rock armour or "Rip-rap" — is rock or other material used to armor shorelines, streambeds, bridge abutments, pilings and other shoreline structures against scour, water or ice erosion.It is made from a variety of rock types, commonly granite or...

, when shorelines or stream banks are fortified for erosion

Erosion

Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...

 protection with large boulders or sizable manufactured concrete objects. When armor is associated with beach

Beach

A beach is a geological landform along the shoreline of an ocean, sea, lake or river. It usually consists of loose particles which are often composed of rock, such as sand, gravel, shingle, pebbles or cobblestones...

es in the form of pebbles to medium sized stones grading from two to 200 millimeters across, the resulting landform

Landform

A landform or physical feature in the earth sciences and geology sub-fields, comprises a geomorphological unit, and is largely defined by its surface form and location in the landscape, as part of the terrain, and as such, is typically an element of topography...

 is often termed a shingle beach

Shingle beach

A shingle beach is a beach which is armoured with pebbles or small- to medium-sized cobbles. Typically, the stone composition may grade from characteristic sizes ranging from two to 200 mm diameter....

. Hydrological modeling indicates that stream armor typically persists in a flood stage

Flood stage

Flood stage is the level at which the surface of a river, creek, or other body of water has risen to a sufficient level to cause damage or affects use of man-made structures...

environment.