Soil erosion can be caused by
a) running water
b) building bunds
c) terrace farming
Answers
Answer: running water
Explanation: Soil compaction, low organic matter, loss of soil structure, poor internal drainage, salinisation and soil acidity problems are other serious soil degradation conditions that can accelerate the soil erosion process. This Factsheet looks at the causes and effects of water, wind and tillage erosion on agricultural land.
Answer:
running water(a)
Explanation:
Even though it can be seen as a natural occurrence, soil erosion is also instigated by other causes. These factors could either be naturally triggered or due to human activities. Soil erosion typically develops slowly and gradually expands to be a menace to the landscape. Mild rills, for example, occurs at its initial stage and grow to be huge galleys which are not only dangerous but also problematic to human activities. Generally, soil erosion is the relocation of the topsoil layer from its original location. It leaves the affected area exposed to more sporadic erosion making it a sequential occurrence. Below are some of the main causes of soil erosion.
1. Water runoff and rainfall intensity
This process begins when the raindrops break down the soil making it vulnerable to movement. The lighter soil aggregates like silt, fine sand, clay, and organic matter are then easily carried away by the moving water. A higher magnitude runoff could lead to erosion of the gravel particles and the other large sand. Splash erosion, though mostly considered as insignificant is also caused by raindrops. The intensity of this erosion is only felt when it occurs in large exposed fields.
2. The slope of the land
The topography of the land may also be a cause of soil erosion. Steeper areas experience a higher intensity of runoff due to the increased speed. Even heavier particles can easily be carried away by the moving water. This reason why hilly areas do face a more violent erosion compared to flat land.
3. Soil texture
The fineness and the structure of soil particles may also prompt the occurrence of erosion. The fine and loose soil structures can be easily carried away more than large and firm soil. The fine soil is more susceptible to the agents of soil erosion hence can easily be moved.
4. Deforestation
When vegetation cover is destroyed, the land gets exposed to the agents of soil erosion. Trees act as barriers against many causes of soil erosion including raindrops and moving wind. Roots also serve in binding the soil together hence cannot be easily disintegrated and made available for the agents of erosion.
5. Wind
Depending on the strength and type of the wind, the upper layer of the unprotected soil can be effortlessly carried away. Whirlwind, for example, with its vigorous rotation, can not only take the soil away but also leave the surface uncovered. On a bare land, the magnitude of wind erosion is felt significantly. Lighter winds do however have a negligible effect on erosion.
6. Land tillage
Land cultivation also exposes soil. Continuous digging destroys the soil structure after some time due to the repeated breakdown of the topsoil layer. Soil particles tend to be disintegrated to finer particles thus remaining susceptible to the agents of erosion over time. Some forms of cultivation in sloppy areas may also aggravate the impact of soil erosion.
7. Overgrazing
Keeping a large stock of livestock in a smaller area will eventually lead to a depletion of the vegetative cover on the land leaving it bare. The continuous pressure on the soil by the animals will destroy the topsoil structure. With this, the soil will simply respond to the natural causes of soil erosion like wind and rainfall. Sheet erosion will consequently occur after some time.
8. Harsh climatic conditions
During extreme climatic situations like drought, tsunami, and many other conditions, massive erosion occurs. In times of drought, for example, the vegetative cover of the soil withers away and the land is left uncovered. In the course of this period also, a fast-moving wind is usually experienced. The wind carries away the fine topsoil. In acute cases like the tsunami, a large mass of soil is carried and deposited in the lowlands.
9. Erodibility of soil
The type of soil moreover affects the potentiality of the occurrence of soil erosion. Fine soil can be easily carried far away by the wind whereas the coarse heavier soil can only be dislodged for short distances. Areas with the finer soil are at a higher risk of intense soil erosion than those with coarse types.
10. Other human activities like quarrying and mining
Such activities expose land to uncontrolled surface drainage and to the other agents of soil erosion as it leaves a bare land surface. The removal of the rocks and sand underground has led to a buildup of deep and dangerous galleys. The soil on the surfaces of the escarpment also gets eroded and disposed of on the lower parts of the quarry.