Editing Soil erosion (section)

==Factors affecting soil erosion==

===Climate===
The [[Quantity|amount]] and [[Intensity mapping|intensity]] of [[rainfall|precipitation]] is the main [[Climate|climatic factor]] [[governing]] soil erosion by water. The [[Relationship science|relationship]] is particularly strong if heavy rainfall occurs at times when, or in locations where, the soil's surface is not well protected by [[vegetation]]. This might be during periods when [[agriculture|agricultural activities]] leave the soil bare, or in [[Semi-arid climate|semi-arid]] regions where vegetation is naturally sparse. Wind erosion requires strong winds, particularly during times of drought when vegetation is sparse and soil is dry (and so is more erodible). Other climatic factors such as average temperature and temperature range may also affect erosion, via their effects on vegetation and soil properties. In general, given similar vegetation and ecosystems, areas with more precipitation (especially high-intensity rainfall), more wind, or more storms are expected to have more erosion.<ref>{{Cite web |title=Raindrops Keep Falling: Understanding and Managing Water Erosion : USDA ARS |url=https://www.ars.usda.gov/oc/utm/raindrops-keep-falling-understanding-and-managing-water-erosion |access-date=2025-04-20 |website=www.ars.usda.gov}}</ref>

In some areas of the world (e.g. the [[Midwestern United States]] and the [[Amazon rainforest|Amazon Rainforest]]), rainfall intensity is the primary determinant of erosivity, with higher intensity rainfall generally resulting in more soil erosion by water. The size and velocity of [[rain drop]]s is also an important factor. Larger and higher-velocity rain drops have greater [[kinetic energy]], and thus their impact will displace soil particles by larger distances than smaller, slower-moving rain drops.<ref>{{cite book|author=Blanco, Humberto|author2=Lal, Rattan|name-list-style=amp|chapter=Water erosion|title=Principles of Soil Conservation and Management|publisher=Springer|year=2010|isbn=978-90-481-8529-0|pages=29–31|chapter-url=https://books.google.com/books?id=Wj3690PbDY0C&pg=PA29}}</ref>

In other regions of the world (e.g. [[western Europe]]), runoff and erosion result from relatively low intensities of [[Precipitation types#Stratiform|stratiform rainfall]] falling onto previously saturated soil. In such situations, rainfall amount rather than intensity is the main factor determining the severity of soil erosion by water.<ref>Boardman, John & Poesen, Jean. Soil Erosion in Europe. John Wiley & Sons. {{ISBN|978-0-470-85911-7}}</ref>

===Soil structure and composition===
[[File:Dead Sea Coastal Erosion March 2012.JPG|thumb|Erosional gully in unconsolidated [[Dead Sea]] (Israel) sediments along the southwestern shore. This gully was excavated by floods from the [[Judean Mountains]] in less than a year.]]
The composition, moisture, and compaction of soil are all major factors in determining the erosivity of rainfall. Sediments containing more [[clay]] tend to be more resistant to erosion than those with sand or silt, because the clay helps bind soil particles together.<ref>{{cite book|author=Mirsal, Ibrahim A.|chapter=Soil degradation|title=Soil Pollution: Origin, Monitoring & Remediation|publisher=Springer|year=2008|isbn=978-3-540-70775-2|page=100|chapter-url=https://books.google.com/books?id=Lr5bMTxom0IC&pg=PA100}}</ref> Soil containing high levels of organic materials are often more resistant to erosion, because the organic materials coagulate soil colloids and create a stronger, more stable soil structure.<ref name="Blanco-2010-p29" /> The amount of water present in the soil before the precipitation also plays an important role, because it sets limits on the amount of water that can be absorbed by the soil (and hence prevented from flowing on the surface as erosive runoff). Wet, saturated soils will not be able to absorb as much rainwater, leading to higher levels of surface runoff and thus higher erosivity for a given volume of rainfall.<ref name="Blanco-2010-p29" /><ref>{{cite book|author=Torri, D.|chapter=Slope, aspect and surface storage|editor=Agassi, Menachem|title=Soil Erosion, Conservation, and Rehabilitation|publisher=CRC Press|year=1996|isbn=978-0-8247-8984-8|page=95|chapter-url=https://books.google.com/books?id=-AqdSMDSUIgC&pg=PA95}}</ref> [[Soil compaction (agriculture)|Soil compaction]] also affects the permeability of the soil to water, and hence the amount of water that flows away as runoff. More compacted soils will have a larger amount of surface runoff than less compacted soils.<ref name="Blanco-2010-p29">{{cite book|author=Blanco, Humberto|author2=Lal, Rattan|name-list-style=amp|chapter=Water erosion|title=Principles of Soil Conservation and Management|publisher=Springer|year=2010|isbn=978-90-481-8529-0|page=29|chapter-url=https://books.google.com/books?id=Wj3690PbDY0C&pg=PA29}}</ref>

===Vegetative cover===
{{See also|Vegetation and slope stability}}
[[Vegetation]] acts as an [[Interface (computing)|interface]] between the [[Atmosphere of Earth|atmosphere]] and the [[soil]]. It increases the [[Permeability (Earth sciences)|permeability]] of the [[soil]] to [[rain]]water, thus decreasing runoff. It shelters the soil from [[wind]]s, which results in decreased [[wind erosion]], as well as advantageous changes in [[microclimate]]. The [[root]]s of the [[plant]]s bind the [[soil]] together, and [[interweave]] with other roots, forming a more [[solid]] [[mass]] that is less susceptible to both [[water]] and [[Aeolian processes|wind erosion]]. The removal of [[vegetation]] increases the rate of [[Erosion|surface erosion]].<ref>{{cite book|author=Styczen, M.E.|author2=Morgan, R.P.C.|name-list-style=amp|chapter=Engineering properties of vegetation|editor=Morgan, R.P.C.|editor2=Rickson, R. Jane|title=Slope Stabilization and Erosion Control: A Bioengineering Approach|publisher=Taylor & Francis|year=1995|isbn=978-0-419-15630-7|chapter-url=https://books.google.com/books?id=3jXg9pyfikQC&pg=4}}</ref>

===Topography===
The [[topography]] of the [[land]] determines the [[velocity]] at which [[surface runoff]] will flow, which in turn determines the [[Erosion|erosivity]] of the runoff. Longer, steeper slopes (especially those without adequate vegetative cover) are more susceptible to very high rates of erosion during heavy rains than shorter, less steep slopes. Steeper terrain is also more prone to mudslides, landslides, and other forms of [[Gravity|gravitational]] erosion processes.<ref>{{cite book|author=Whisenant, Steve G.|chapter=Terrestrial systems|editor=Perrow Michael R.|editor2=Davy, Anthony J.|title=Handbook of Ecological Restoration: Principles of Restoration|publisher=Cambridge University Press|year=2008|isbn=978-0-521-04983-2|page=89|chapter-url=https://books.google.com/books?id=moJHjZ9qW_8C&pg=PA89}}</ref><ref>{{cite book|author=Blanco, Humberto|author2=Lal, Rattan|name-list-style=amp|chapter=Water erosion|title=Principles of Soil Conservation and Management|publisher=Springer|year=2010|isbn=978-90-481-8529-0|pages=28–30|chapter-url=https://books.google.com/books?id=Wj3690PbDY0C&pg=PA28}}</ref><ref>{{cite book|author=Wainwright, John|author2=Brazier, Richard E.|name-list-style=amp|chapter=Slope systems|editor=Thomas, David S.G.|title=Arid Zone Geomorphology: Process, Form and Change in Drylands|publisher=John Wiley & Sons|year=2011|isbn=978-0-470-71076-0|chapter-url=https://books.google.com/books?id=swz4rh4KaLYC&pg=PA209}}</ref>