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الموضوع: Factors affecting soil erosion
14-10-2009, 09:53 PM #1
Factors affecting soil erosion
Factors affecting soil erosion
Different factors affecting the vulnerability of soil erosion as the mechanism by which soil erosion.
A. Factors affecting soil erosion in the water
There are many factors affecting the rate of soil erosion, water, some of which are related to the nature of rainfall, some of which is related to the nature of the soil itself and installed, some of which is related to Btabgravep the region, including ones related to vegetation, and some are related to human activity.
(1) the size of raindrops Rain drop size
The larger the raindrops falling increased kinetic energy of the phones, because the kinetic energy of the body is equal to hit the block holds the body in the box, the speed of a moving object, and then the capacity of the largest raindrops on bare soil being washed from the vegetation, where increasing the amount of soil particles from the impact of volatile A drop of rain, increasing the distance that you jump to this Alhabayat volatile.
(2) heavier downpour Rainfall intensity
Abundance of rain is the amount of rain falling on a specific area of the Earth's surface within a specified time.
The amount of rain Almatargzarp =
Area × time
The more abundant downpour increased the rate of soil erosion, because of the increased amount of runoff over the soil surface. Valmatar when he falls on the soil surface either seep into the soil which is known as colds or Leakage, or remain on the soil surface, and then flows towards the bottom of the slope which is known as surface runoff. The greater the abundance of rain for the rate of leakage of water into the soil, increased the rate of runoff over the soil surface and then increased its ability to excavate soil.
(3) permeability of soil Soil permeability
The greater the permeability of the soil increased the amount of rain leaked into the soil at the expense of quantity, which is flowing above the soil surface, thus reducing the rate of soil erosion in this running water over the soil surface.
It is intended Bnvavep soil ability to deliver water, or ease of movement, in Fragadtha. This depends on the permeability pore, and the size of the vacuum one, and the extent to spaces with each other.
If the spaces in the soil is not connected to each other, the permeability is low, even if the porosity is high, and the size of one large space. It is not, necessarily, the top soil porosity, permeability is the highest; because it must be correlated increase in porosity and the extent of the vacuum one. Therefore, the clay soil, the higher the porosity of clay soils, which are less permeable; because the size of the vacuum one, in the first, very small; what makes the friction takes up a lot of energy, and limiting the speed of movement of water. There are many factors, which control the volume per void in the soil, and then, in the permeability. The most important are:
(A) the size of soil particles
Does not affect the grain size of soil porosity, other factors being equal, such as particle agglutination method, and the extent of homogeneity; but is it too much to influence the permeability; because the smaller particle size, the small size of the void one; and vice versa (see the form of the impact of grain size of soil permeability soil).
(B) the method of compaction of soil particles
Method of compaction of soil particles, which affect the porosity, and permeability together. In stacking Cube Cubic, the porosity is high, and the size of one large space; what makes high permeability. If soil particles regrouped in the form of hexagonal prismatic Rhombohedral, the porosity decrease, and getting smaller volume per void; what makes low-permeability
C) the homogeneity of the size of soil particles
Affects the homogeneity of the size of soil particles, in both the permeability and porosity; As long as the size of the particles more homogeneous, the porosity of the soil is high, and the size of one large space; what makes high permeability. If the particle size is not uniform, the smaller ones, fill the spaces between the Kberatha; reduces the porosity of the soil, and reduces the size of the void one; become strained permeability (d) the extent to soil pores
If there is no connection between the pores of the soil, the water, can not move in these clogged pores. What is going on is usually rocks; but it may haunt the soil, due to blockage of some materials Msamadtha carnivores, such as: silica SiO2, and limestone CaCO3, and iron oxides Fe2O3, and gypsum CaSO4. 2H2O.
The sandy soils are usually high permeability, which reduces the rate of runoff from rain water over the soil surface in sandy soils and therefore less likely to erosion. The Vtkon permeability clay soils, usually, the ratio of civilian to the disposal of rain in the form of runoff or Laminated Prosecutors in row over the soil surface at the expense of increasing the proportion of rain water leaking into the soil, with the increasing proportion of runoff in clay soils increase the chances of soil erosion with these running water over the soil surface.
(4) the size of soil particles Particle size
The larger the mass of soil particles increased, and then difficult to running water above the soil surface shelves, so check to increase the strength of resistance of these particles.
Resistance force = weight beloved × × cos angle regression coefficient of friction
Weight = mass of the beloved beloved × gravity acceleration
Therefore, there will be inversely proportional to the rate of soil erosion and the size of soil particles of equal other conditions. We find that the soils in which the surface of the brush covered Measles and stones are resistant to erosion from running water, and vice versa, for the soils in which the strength of applied surface smooth.
(5) fusion of soil particles
Than the cohesion of soil particles from the resistance to erosion from running water, because this consistency both in organic matter, salts or clay minerals prevent the uprooting of these particles with running water. Therefore, we find that the loose soil, whether naturally fragmented because of their poverty these articles carnivores or broken by man more vulnerable to erosion, surface runoff.
(6) surface slope Slope
The greater the surface slope angle increased the rate of soil erosion, whether by jumping from the impact of falling raindrops or by running water over the soil surface. Increased erosion caused by rain drops falling due to the distance that Tagafzha grains blowing in the direction of the slope increases with increasing slope angle (see the form of angle sloping surface soil). The increase in soil erosion from running water with increasing slope angle of soil is attributable to an increase in the momentum of running water, which is directly proportional to the sine angle regression.
Runoff depth × density of the liquid body space × × sine of Alanhaddarkop payment stream =
In addition to the low resistance to erosion of soil particles which direct proportion to the cosine of the angle regression.
Resistance force = weight coefficient of friction beloved × × cosine of the angle regression
Therefore, we find that the soils of steep mountain areas suffer much higher soil erosion, unless there is a counter-measures to reduce the surface slope, such as building terraces on the mountain slopes often widespread in such areas such as mountain deployed since the time provided in the mountainous Asir region in southwestern Saudi Arabia and the highlands of Yemen.
(7) along the slope Slope Length
Affect the length of the slope on the rate of soil erosion by increasing the amount of runoff you'll find further down the slope, which in turn increase the rate of soil erosion, especially as the capacity to pay the torrent direct proportion to the depth, as is evident in the equation in the paragraph above.
(8) form of the slope Slope Shape
Are intended to change the pattern of the slope of the gradient along the slope. Vtkon significant erosion in the slopes convex Convex (the rate of soil erosion of the slope convex), since the gradient of a maximum at the bottom of the slope where the amount of runoff has increased. The slopes concave Concave Vicu rate of soil erosion is less because most part of the slope is steeper at the top of the slope, before the amount of runoff
Vegetation helps to reduce soil erosion rates are great, and the proportion increases with the intensity of that cover. Valgueta vegetation prevents the rain drops falling from the impact surface of the soil and thus have prevented the soil from erosion by particles flying from the impact surface of the soil drops. Vegetation is also working to increase the coherence and resistance to soil erosion through a network of roots, while the upper part of the plant above the soil surface thereby acting to reduce the speed of runoff and thereby reduce its ability to excavate soil and the roots of plants help to create large pores in the soil increases the permeability of soil and thus increase the leakage of rain into the soil at the expense of runoff which reduces the rate of soil erosion. Therefore, we find that the forests were cut trees to sell wood or to place agriculture suffered greatly from erosion, which is one of the most important factors of desertification in the world. Also, the agricultural fields that are bare of vegetation after harvest and before the completion of the new growth of the crop exposed to soil erosion significantly, especially if this period coincided with the rainy season.
(10) soil tillage
When the tractor tilling the soil for the cultivation of crops, the soil be a: theyre vulnerable to erosion from running water because tillage reduces the coalescence and cohesion of soil particles. And highlights the problem of soil erosion due to tillage significantly in the mountainous areas where the degree of surface slope is high. The problem is compounded when the date coincides with the plowing season rainfall.
ASSINGMENT :U OF KFACULTY OF AGRICULTUReDEPT. OF AGRIC. ENGINEERINGMs.c Bath (9)
Factors affecting soil erosion
Prepared by:AMAR ABDALJABEER MOHAMD
مواضيع مشابهة:Manchester2009اللهم أرحم والداي