Transcript
Page 1: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion
Page 2: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

Soil ErosionSoil Erosion

• Detachment, Transportation and deposition of soil material

Types of Erosion

1. Geological erosion

2. Accelerated erosion

Page 3: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

Geological ErosionGeological Erosion

• It is also called natural erosion or normal erosion

• The erosion which is undisturbed by human activity

Types

• Water erosion

• Wind erosion

Page 4: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

Water ErosionWater Erosion

Removal of soil mass by running water from snow and ice melt,and

transporting it usually downhill

Forms of water Erosion

• Sheet erosion

• Rill erosion

• Gully erosion

Page 5: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

Sheet ErosionSheet Erosion

Uniform removal of soil in thin layers resulting from sheet or over land flow of water occuring in thin layers

• It causes the color of land to chang gradually from dark to light,usually this change in color is accompnied by progressive decline in yield

Page 6: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

Rill ErosionRill Erosion

• It is the advanced satge of sheet erosion

• When sheet erosion continues for sometime and the land is neglected rills start deepning and widening so tht runoff concetrates through them.These rills then go on developing with the passage of time and prove fore runners of gullies.this stage of erosion is called rill erosion

Page 7: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

Gully ErosionGully Erosion

• It is the advanced stage of rill erosion

Stages of gully development

• Formation of rills by sheet washing

• Deepning and cutting of rills

• Start of under cutting of rocks

• Eating of backwards and uphill by gullies

Page 8: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

Process of Water ErosionProcess of Water Erosion

• Detachment

• Transportation

• Deposition

Page 9: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

Damages of Water ErosionDamages of Water Erosion

• Washing of soil

• Loss of fertile soil

• Increase runoff

• Top soil removal

• Decrease infiltration capacity

• Stones will be left

• Effect on wild life

Page 10: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

Wind ErosionWind Erosion

Erosion which is caused by wind is called wind erosion

• In Pakistan, 40 % area is affected by wind erosion e.g Thal, Cholistan and D. G. Khan

It occurs in

• Dry lands

• In arid and semi arid areas

Page 11: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

Process of Wind ErosionProcess of Wind Erosion

1. Initiation of soil movement

• The turbulance of wind, together with its velocity is responsible for starting the movement of soil in wind erosion process

• Minimum velocity of wind required to initiate soil movement is called threshhold velocity of wind.It greatly depends upon the size of soil grain

• There is a range of threshold velocities for any soil depending upon previous history of field

Page 12: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

2. Transportation of Soil2. Transportation of Soil

• Transportability of soil depends upon the size of soil particles

• Fine dust once lifted, may be carried to great distances from the eroding areas

Page 13: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

3. Deposition of Atmospheric Load3. Deposition of Atmospheric Load

• Material carried either in suspension or saltation is deposited primarly when the wind velocity decrease

• The process of picking up and depositing material is continuous is due to variable character of wind and to the nature and process of saltation

Page 14: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

Modes of Sand TransportModes of Sand Transport

Depending upon wind force, sand particle’s and mass

a.Saltation

• Progression of particles in succesive jumps

• Size of particles 0.1 to 0.5 in diameter most susceptible

Page 15: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

b. Surface Creepb. Surface Creep

• The soil particles with diameter 0.5-1 mm are too heavy to be moved by saltation but are pushed along the surface by the impact of particles to surface creep.

Page 16: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

c. Suspensionc. Suspension

• Very fine dust particles less than 0.05mm in diameter are carried in true suspension,

• The amount of sand transported in suspension is only a very small portion of total.

Page 17: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

DamagesDamages

• Loss of fertility

• Accumulation of materials

• Uprooting of seedlings

• Weed seed transportation

• Covering of roads and railway tracks

• Air pollution

• Damage of agri. machinery

Page 18: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

2.Accelerated Erosion2.Accelerated Erosion

• The deterioration of soil as a result of man’s activities is called accelerated erosion.

• It is also called abnormal erosion

• It is associated with changes in natural vegetation and soil conditions.

Page 19: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

Kinds of intensities of soil erosion Kinds of intensities of soil erosion

Kind of erosion Intensity of hazard

Affected area (mha)

Water erosion (11.18mha)•Sheet &rill erosion•Sheet &rill erosion•Rill &gully erosion•Gully erosion

Slight

Moderate

Severe

Very severe

0.40

3.58

3.75

3.45

Page 20: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

Kinds of intensities of soil erosionKinds of intensities of soil erosion

Kind of erosion Intensity of hazard

Affected area (mha)

Wind erosion (4.73mha)•Light wind erosion•Moderate wind erosion•Severe wind erosion

Slight

Moderate

Severe

2.56

0.50

1.67

Page 21: Soil Erosion Detachment, Transportation and deposition of soil material Types of Erosion 1.Geological erosion 2.Accelerated erosion

Top Related