Source: http://www.bbc.co.uk/insideout/southwest/series4/coastal_path.shtml



NATURAL FACTORS:

Slope Gradient-
The steeper the slope, the greater the soil loss from erosion caused by water as more soil is washed down the slope (channel for water to flow) by heavyrainfall.

Slope Length-
Due to more runoff collected as the slope length increase, soil erosion by water also increases. This is due to the increased speedof water which enables agreater capacity of sediment to be carried down the path.

Resistance of Various Soils-
Soil erodibility is an estimate of the ability of soils to resist erosion, based on the physical characteristics of eachsoil.Generally, soils with faster infiltration rates, higher levels of organic matter and improved soil structure (aggregation of individual soil particles into larger aggregates) have a greater resistance to erosion. Sand, sandy loam and loam textured soils tend to be less erodible than silt, very fine sand, and certain clay textured soils.In turn, soil erodibility is affected by tillage (agricultural preparation of the soil) and cropping practices which may lower soil organic matter levels that cause poor soil structure.Lastly, as soils on eroded areas have poorer structure and lower organic matter than original soil, they have a higher possibility of being washed away by erosion.

Impacts of Rainfall on Soil-
Raindrops can break down and disperse soil particles when they fall on soil surfaces, thus causing erosion. Lighter materials such as very fine sand, silt and clay are easily removed by the impacts of raindrops and runoff water while greater raindrop energy or amount of runoff might be required to move the larger sand and gravel particles. Therefore, it is vital to hold loose soil together.Moreover, a single raindrop has such a strong impact that it is able to move the soil particles two feet away! This causes the topsoil to be pack tightly together, forming a hard layer which prevents the growth of vegetation.Still, not decomposed organic residues present at the soil surface protect the soil against raindrop impacts.

Lack of Residue Covers-
The possibility of soil erosion increases with the lack of residue covers such as plants. By protecting the soil from raindrop impact and splash, plants slow down the movement of surface runoff, allowing excess surface water to penetrate.Moreover, smooth or not ridged soil surfaces have little resistance to the wind thus soil erosion can occur easily.



HUMAN FACTORS:

Misuse of Pathways-
By not following the paths provided, vegetation at the sides of the path will be lost. The lack of vegetation merely accelerates the rate of erosion as there is nothing to hold the loose soil together.

Carried out Activities-
Mountain Biking: Causes excessive damage on grassy routes, thus degrading it as

• More footpath erosion is caused by the high pressure exerted by bikes
• The wheels of the bike destroy grasses that hold the soil firmly on the ground
• Sand stuck on to the wheels of the bike will be carried away and may even pollute nearby water sources

Orienteering and gathering of natural herbs: Increases the rate of footpath erosion

• Running around to find checkpoints increase footpath erosion due to pressure inflict on ground
• Destroy grasses that hold the soil firmly on the ground

Camping: Destroys natural vegetation thus, removing limited residue covers

• Destroy grasses that hold the soil firmly on the ground
  

Usage Level-
National Parks are most at risk of footpath erosion as they are open to thousands of people who destroy nature simply by trampling on the ground.

Pressure on Soil-

When we step on soil, we

• Loosen the soil, causing it to move apart
• Compress the soil, resulting in lesser water retention which is able to support less wildlife than usual
• Expand paths, especially when we walk around muddy paths in an attempt to avoid the surface runoff
  

Extent of Footpath erosion-

Source: http://www.townleygrammar.co.uk/departments/library/lake%20district/Erosion.pdf