Types of Soil Erosion (III)
b) Slope of terrain.
Normally, one would expect that the erosion would increase as they did the degree and slope length, as a result of corresponding increases in speed and volume of surface runoff. Also, while on a flat surface the patter of raindrops throws soil particles randomly in all directions, in steep slope conditions more soil is splashed it down than up increasing the proportion as does the degree (Morgan, 1986).
In theory, law of falling bodies, the water velocity varies with the square root of the vertical distance it travels, and its erosive capacity with the square of the velocity, that is, if the slope is increased four times , the velocity of water flowing over it is duplicated, and quadrupling its erosive capacity.
B. WIND EROSION
Occurs when the wind carries tiny particles that hit a rock and fall into more particles that are colliding with other things. It is usually found in deserts and mountains dune forms rectangular or even in relatively dry areas. This entails a longer time because of the time it takes to erode.
C. AND OTHER FACTORS
1. topsoil erosion. Group the forms of erosion that occur on land surfaces, whose expression responds to a gradual manifestation: splash erosion, sheet erosion, rill erosion and gully erosion.
a.) splash erosion. It is caused by falling raindrops on the ground, its impact is a function of the shape and size of the drops (EROS), and soil resistance to erosive (erodibility). The kinetic energy of the drops (1 / 2 m v2) depends on the properties for them cited the effect of the spill is especially dramatic in subtropical climate which combines heavy rainfall and unfavorable soil protection, and, Soyer (1987) found minimal soil loss by splashing in plots located in Zaire, Africa, where forest cover was present, reaching values ??of 3.1 to 7.2 ton ha-1 yr-1, whereas under maize cover values mass loss was of 188 ton ha-1 yr-1.
The terminal velocities for various diameters and heights of fall of raindrops can be seen in Table 6, which senses the potential effect of a falling drop of rain from the canopy of a forest (8 m) Should you find a soil with poorly developed litter horizon as already noted.
b.) Gully Erosion:
Once you start the formation of the gully, it evolves according to the relative consistency submitted by the different soil horizons, when the consistency of the material is relatively uniform, the walls of the gully are more or less vertical, so that when presented an increase in the resistance of the lower layers, are developed in a “V”. FAO (1967) describes the growth of gullies as a result of different processes, which act either isolated or combined, as follows:
- Rubbing on the bottom or sides of the gully with the flow of water and abrasive materials (soil particles or debris carried by the water).
- Erosion by water rushes into the head of the gully, and progressive causes this regression.
- Desmorronamiento on both sides of the gully by the lubricating action of water infiltration.
Smith also mentions the formation of gullies from subsurface channel models and tunnel erosion (Figure 4).
Gullies figure 3 in an advanced state of development in Rio Negro, Antioquia (Colombia)
Types of gullies. According to the way the gullies can be classified into six different categories, whose description is applicable under the approach of Peralta (1977) cited by Moder (1983a).
- Linear: so long and narrow head, a few tax on its sides, can stretch and give rise to other types.
- Bulbosa wide and spatulate at the top and can be linear in its lower part, often follows the course of an old drain. Have small tax on all sides, to leave the building gives rise to dendritic gully.
- Dendritic: formed by many tributaries or branched, may arise along the lines of natural drainage, his head may have a semi-circle.
- Lattice: the tributaries entering the channel forming about an angle of 90 °, takes place mainly in flat areas.
- Parallel: composed of one or more gullies that drain into one.
- Compound: combinations of two or more forms, occurring mainly in areas with advanced problems of erosion.
c.) mass movements.
These movements have been largely neglected in the context of the study of soil erosion (Morgan, 1986), however, in many cases they are the dominant form of erosion processes. Its importance, enhanced in certain climatic conditions in the tropics, it is even clearer if you understand these movements as precursors to other erosion processes, as erosive agents benefit from the generation of areas highly susceptible to intervention. The displaced soil mass usually lose the protective cover, promoting the infiltration process, in this way achieve full expression of separation-disintegration of particles and surface runoff, the latter variable depending on the micro and macro topographic conditions.
credit to: Wildor Huanca Apaza
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