Soil erosion (IGKV RAIPUR, C.G)

2. SOIL EROSION
 Mining of soil erosion:-
 Soil erosion is the process of detachment of soil
particles from the parent body and transportation of the
detached soil particles by wind and water.
 The agents causing erosion are wind and water.
 The detaching agents are falling rain drops, channel
flow and wind.
 The transporting agents are flowing water, rain splash
and wind.
 Depending on the agents of erosion, it is called as
water erosion or wind erosion or wave erosion.

3.  Definition of soil erosion :-
 “Soil erosion is the wearing away of the land
surface by physical forces such as rainfall,
flowing water, wind, ice, temperature change,
gravity or other natural or anthropogenic
agents that abrade, detach and remove soil
or geological material from one point on the
earth’s surface to be deposited elsewhere.”

4.  Extent of soil erosion;-
 Soil Erosion in India is amongst the leading areas of
concern for the Government of India.
 It affects cultivation and farming in the country in
adverse and unfavourable ways.
 Soil erosion leads to deprivation of physical
characteristics of soil and damages plant and crops.
 In India almost 130 million hectares of land, that is,
45% of total geographical surface area, is affected by
serious soil erosion through gorge and gully, sifting
cultivation, cultivated wastelands, sandy areas, deserts
and water logging.

5.  Extent of soil erosion;-
 Soil erosion by rain and river that takes place in
hilly areas causes severe landslides and floods,
while cutting trees for agricultural implements,
firewood and timber;
 Grazing by a large number of livestock over
and above the carrying capacity of grass lands,
traditional agricultural practices, construction of
roads, indiscriminate quarrying and other
activities, have all led to the opening of hill-faces
to extreme soil erosion.

6.  Extent of soil erosion;-
 A joint FAO/UNEP assessment of land
degradation around the world has come up with
the following findings;
 In Africa north of the equator, 11.6% of the total
area is affected by water erosion and 22.4% by
wind erosion.
 In the Near East, 17.1 % of the total area is
affected by water erosion; 35.5 % by wind
erosion, and 8 % by salinization.

7. TYPES OF SOIL EROSION
 Natural or Geologic Erosion
 Accelerated Soil Erosion
 Water Erosion:-
 Splash Erosion
 Sheet Erosion
 Rill Erosion
 Gully Erosion
 Stream-bank Erosion
 Wind Erosion:-
1) Deflation
 Surface creep
 Saltation
 Suspension
2) Abrasion

8. TYPES OF SOIL EROSION
A) Natural or Geologic Erosion:-
 It is caused by nature.
 Normal or geologic erosion is a normal feature of any
landscape.
 Geologic erosion takes place gradually but so slowly that
ages are required for it to make any noticeable alteration
in the major features of the earth’s surface.
B) Accelerated Soil Erosion:-
 It is caused by human activities.
 This accelerated detachment that rapidly ravages the land
and it is with this type of soil erosion that is considered of
a serious concerned.
 Nature requires, on an average, about 1000 years
building 2.5 cm’s of top soil but wrong farming methods
may take only a few years to erode it from lands of
average slope.

9. TYPES OF SOIL EROSION
C) Water Erosion :- Water erosion causes severe soil
erosion and this category of soil erosion can be defined,
splash erosion, sheet erosion, rill erosion, gully erosion
and stream-bank erosion.
1) Splash Erosion:-
 Splash erosion is the first stage of the erosion process.
 It occurs when raindrops hit bare soil.
 The explosive impact breaks up soil aggregates so that
individual soil particles are ‘splashed’ onto the soil
surface.
 The splash particles can rise as high 60cm above the
ground and move up to 1.5 meters from the point of
impact
 The particles block the spaces between soil aggregates,
so that the soil forms a crust that reduces infiltration and
increases runoff.

11. TYPES OF SOIL EROSION
2)Sheet Erosion:-
 In the initial stages of soil
erosion, rain drops churn the
top soil and along with runoff
the muddy water moves away
from the field.
 It is uniform removal of top soil in thin layer from the
field.
 It is least conspicuous and is the first stage of
erosion.

12. TYPES OF SOIL EROSION
3) Rill erosion:-
 When runoff starts,
channelization begins
and erosion is no longer
uniform.
 Incisions are formed on the ground and
erosion is more apparent than sheet erosion.
 This is the second stage of erosion.

13. TYPES OF SOIL EROSION
4) Gully Erosion:-
 Unchecked rills result
in increased channelization
of runoff.
 Gullies are formed when
channelized runoff from vast
sloping land is sufficient in volume and velocity
to cut deep and wide channels.
 Gullies are the most spectacular symptoms of
erosion.
 If unchecked cultivation becomes difficult.

14. TYPES OF SOIL EROSION
5) Stream-bank Erosion:-
 Small streams, rivulets,
torrents (hill streams) are
subjected to stream-bank
erosion due to obstruction
to their flow.
 Vegetation sprouts when
the streams dry up and obstructs the flow
causing cutting of bank or changing of the
flow course.

15. TYPES OF SOIL EROSION
D) Wind Erosion:- Wind erosion is the movement and
deposition of soil particles by wind. Wind erosion is a
serious problem in area where land is bare and devoid of
vegetation. It is a natural phenomena in arid and semi-arid
zones. When it’s velocity overcomes the gravitational and
cohesive forces of the soil particles, wind will move soil and
carry it away in suspension.
 Wind erosion is of two primary varieties:
1) Deflation:- Where the wind picks up and carries away loose
particles.
2) Abrasion:- where surface are worn down as they are struck
by airborne particles carried by wind.
 Deflation is divided into three categories:
 Surface creep
 Saltation
 Suspension

16. TYPES OF SOIL EROSION

17. TYPES OF SOIL EROSION
1) Surface creep:- (1) Rolling of coarse grains, larger
than 0.5 to 3 mm in diameter and too heavy to be
lifted, by wind along the surface of the ground is called
surface creep. (2) The particles are pushed along the
surface of the ground, rolling and not jumping. (3)
Generally, 5 to 25 % weight of the soil lost by wind
erosion is carried in surface creep.
2) Saltation:- (1) Saltation is the first stage of movement
of soil particles in series of jumps. (2) The soil
particles moved by saltation are between 0.1 to 0.5
mm in diameter(fine sand). (3) Sand sized particles
rolling along the surface start this movement. (4) Due
to the effect of wind, soil particles jump up vertically
into air and rice to a height of 30 to 60 cm and fall
through the air. (5)Generally 50 to 75 % of the weight
of soil lost by wind erosion is carried in saltation.

18. TYPES OF SOIL EROSION
3) Suspension:- (1)Floating of fine dust
particles through the air is known as
suspension. (2)The particles are smaller then
0.1 mm in diameter. (3)The smaller particles
are kicked into the air, they stay in
suspension and carried very long distances,
even several thousands of kilometres. (4)The
dust comes down to earth only with rain or
when wind velocity is decreased. (5)
Generally 3 to 4 % of the weight of soil lost
by wind erosion is carried in suspension.