Erosion

Erosion Erosion is the process by which material is removed from a region of the Earth surface. It can occur by weathering and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere. It usually occurs due to transport by wind, water, or ice; by down-slope creep of soil and other material under the force of gravity; or by living organisms, such as burrowing animals, in the case of bioerosion.

Although erosion is a natural process but human land use policies also have an effect on erosion, especially industrial agriculture, deforestation, and urban sprawl. Land that is used for industrial agriculture generally experiences a significantly greater rate of erosion than that of land under natural vegetation, or land used for sustainable agricultural practices.

Erosion Processes Gravity Mass wasting or Mass movement is the down-slope movement of rock and sediments, mainly due to the force of gravity. Mass movement is an important part of the erosional process, as it moves material from higher elevations to lower elevations where other eroding agents such as streams and glaciers can then pick up the material and move it to even lower elevations. Mass-movement processes are always occurring continuously on all slopes; some mass-movement processes act very slowly; others occur very suddenly, often with disastrous results. Any perceptible down-slope movement of rock or sediment is often referred to in general terms as a landslide.

Example of mass wasting at Palo Duro Canyon

Talus cones produced by mass wasting, north shore of Isfjord, Svalbard, Norway

Water Splash erosion is the detachment and airborne movement of small soil particles caused by the impact of raindrops on soil. In rain splash soil particles are knocked into the air by raindrop impact. Sheet erosion is the detachment of soil particles by raindrop impact and their removal down slope by water flowing overland as a sheet instead of in definite channels or rills. the loose particles are moved down slope by broad sheets of rapidly flowing water filled with sediment known as sheet floods. This stage of sheet erosion is generally last only for a short time.

Splash erosion Sheet erosion Splash erosion gauge

Rill Erosion Rill erosion refers to the development of small, ephemeral concentrated flow paths, which function as both sediment source and sediment delivery systems for erosion on hill slopes.

Bank Erosion Bank erosion is the wearing away of the banks of a stream or river. Erosion and changes in the form of river banks may be measured by inserting metal rods into the bank and marking the position of the bank surface along the rods at different times.

Shoreline Erosion or Coastal Erosion Shoreline erosion or Coastal erosion primarily occurs through the action of currents and waves but sea level (tidal) change can also play a role.

ICE Ice erosion can take one of two forms. It can be caused by the movement of ice, typically as glaciers, in a process called glacial erosion. It can also be due to freeze-thaw processes in which water inside pores and fractures in rock may expand causing further cracking.

Wind In arid climates, the main source of erosion is wind. The general wind circulation moves small particulates such as dust across wide oceans thousands of kilometres downwind of their point of origin, which is known as deflation. There are two main effects in wind erosion. First, wind causes small particles to be lifted and therefore moved to another region. This is called deflation. Second, these suspended particles may impact on solid objects causing erosion by abrasion (ecological succession). Wind erosion generally occurs in areas with little or no vegetation, often in areas where there is insufficient rainfall to support vegetation. An example is the formation of sand dunes, on a beach or in a desert.

Erosion Measurement Erosion is measured using tools such as the micro-erosion meter (MEM) and the traversing micro-erosion meter (TMEM). The MEM has proved helpful in measuring bedrock erosion in various ecosystems around the world. It can measure both terrestrial and oceanic erosion. On the other hand, the TMEM can be used to track the expanding and contracting of volatile rock formations and can give a reading of how quickly a rock formation is deteriorating.