Types of Erosion

a. Splash Erosion: It is the detachment and airborne movement of small soil particles caused by the impact of rain drops on soil.

b. Sheet Erosion: According to Carla (2008) it is the detachment of soil particles by raindrop impact and their removal of down-slope by water flowing over land as a sheet instead of indefinite channel or rills. The impact of the raindrop

breaks apart the soil particles of clay, silt and sand into the soil pores thus reduce infiltration. Once the rate of falling rain is faster than infiltration, run-off takes place. There are two stages of sheet erosion; the first is rain splash, in the soil particles are knocked into the air by raindrops impact. Secondly, the loose particles are moved down-slope by broad sheets of rapidly flowing water-filled with sediment known as sheets flood. This stage of sheet erosion is produced by cloud burst, sheet floods which commonly travel short distances and last only for a short time.

c  Rill Erosion: According to Henderson (2006), it refers to the development of small ephemeral, concentrated flow path, which function as both sediment source and sediment delivery system for erosion in hill slope. Where water erosion rates on disturbed up land area are greatest, rills are active. Where precipitation rates exceed soil infiltration rates, run-off causes more erosion than the initial raindrop impact. This type of erosion occurs in Agbor drainage system after a heavy down pour.

d  Gully Erosion:  Bunnet and Okunrotifa (2003), also called ephemeral, gully erosion, occurs when water flows in narrow channels during or immediately after heavy rain or during melting snow. This is particularly noticeable in the formation of hollow ways where tarmac and old rural roads has over many years become much lower than the surrounding field. A gully is deep, ranging from 1 to 2 feet (0.61m) to as much as 75 to 100 feet (30m). According to Morgan (2006), it is more localized and occurs when heavy rainfall rushes down a steep slope, cutting deep grooves into the land. The grooves become deepened and widened to form gullies.

e  River Bank Erosion: According to Olatunji (2003), it is the wearing away of the banks of a stream or river. It is distinguished from changes on the bed of the water course, which is referred to as scour erosion and changes in the form of river banks. May be measured by inserting metal rods into the banks and making the position of the bank surface along the rods of different times. This erosion generates movement of water and rise in water level during flooding.

f   Coastal Erosion: Much like river banks erosion, it occurs along sea and ocean coast during flooding, leading to sea rise and flooding.

g Wind Erosion: Birkeland (2006) states that wind erosion is more likely  to occur in dry area where soil is loose and unprotected by vegetation.

References

Birkeland, P. W. (2005): Soil and Geomorphology. New York: Oxford University Press. Pp 52, 70.

Bunnet, R.B. and Okunrotifa, P. O. (2003): Geography in Diagrams for West African 8^th ed., Longman Group Limited, pp 35, 63, 84.

Carla, W. (2008): Environmental Geology 5^th ed, McGraw-Hill Inc. USA pp 20-22.

Henderson, (2006): “Causes and Effects of Soil Erosion” Omaff Fact Sheet Index 573.

Morgan, R.P. (2006): Soil Erosion, London Longman Group. Pp 22, 26, 71

Olatunji (2003): Health, Safety and Environment, A conference Paper on EHOAN. Pp14-15.