3rd semester

-Erosion.

CONTENTS

-Mechanics of erosion.

-Black Sunday

-Types of Erosion

- Agents of Erosion.

-Classification of Erosion.

-Water erosion and its types.

-Factors affecting water Erosion.

-Wind erosion.

- Methods of Soil conservation.

-How to conserve soil ?

The erosion termed indicates the meaning of

soil remove from one place and depositing them

to some another place.

“Removal of soil from its original position”

“It is the process of detachment,

transportation & deposition of soil materials

from one place to another by erosive agents”

Every year in India 16.5 tons/ha/year soil

erosion is occur by agents of erosion.

WHAT IS EROSION ?

Mechanics of erosion

A) Detachment.

B) Transportation.

C) Deposition.

Types of Erosion

In general there are two types of soil erosion.

1. Geological Erosion:-

It is caused by nature.

2. Accelerated Erosion:-

It is caused by human activities.

Agents of Erosion

1. Wind. - ERODIBILITY

2. Water. - EROSIVITY

3. Temperature.

4. Biological Factors.

Classification of Erosion

Depending upon the erosion causing

factors

A) Wind Erosion.

B) Water Erosion.

Types of water erosion:-

1.Rain splash erosion.

2.Sheet erosion.

3.Rill erosion.

4.Gully erosion.

5.Stream bank erosion.

Other forms of erosion:-

1.Glasical erosion.

2.Snow erosion.

3.Organic erosion.

4.Underground Erosion.

5.River erosion.

• Rain Splash Erosion:Rain splash erosion is caused by the impact of

water striking the surface of soil.

It takes place in two steps.

1. As precipitation fills the pore spaces, loosening

& driving soil particles apart.

2. Impact of subsequent rain drops hitting the

surface, transporting particles to other area.

Sometimes water flows as a sheet over

large areas down a slope. In such cases

the top soil is washed away. This is

known as sheet erosion.

Sheet Erosion

Rill Erosion.It is caused by water concentrating into

innumerable, closely spaced small channels.

Left unchecked, rills can cut vertically &

horizontally and when joined form gullies.

• Gullies: The running water cuts

through the clayey soils and

makes deep channels as gullies.

Gully erosion

Stream Erosion.When flow in gullies become permanent,

it is called a stream which may be

permanent or seasonal is called as stream

erosion.

Factors affecting water Erosion

A) Climate.

1. Precipitation.

2. Temperature.

3. Wind.

4. Humidity.

5. Solar radiation.

B) Soil.

1. Physical properties of

soil.

2. Vegetation cover.

3. Organic matter

contents in soil.

4. Moisture contents of

soil.

5. Soil density.

It is the process in which removal of soil

particles moves one place to another place by

wind in known as wind erosion.

Wind erosion

Black Sunday

• April 14th,1935 black

Sunday was the worst

blizzard of the dust storm

with high speeds which

caused the most extensive

damage. It occurs in

United states in Boise city

at 5:15 PM. It is estimated

to have displaced 300

thousand tons of topsoil

from the Prairie area in the

US.

Methods of Soil conservation

• ii. Terrace Farming:

Steps can be cut out on

the slopes making

terraces. Terrace

cultivation restricts

erosion. Western and

central Himalayas have

well developed terrace

farming.

i. Contour Ploughing:

Ploughing along the

contour lines can

decelerate the flow of

water down the slopes. It

used in tea cultivation.

• iii. Strip Farming:

Large fields can be divided

into strips. Strips of grass

are left to grow between

the crops. This breaks up

the force of the wind.

• iv. Shelter Belts: Planting

lines of trees to create

shelter also works in a

similar way. Rows of such

trees are called shelter

belts. These shelter belts

have contributed

significantly to the

stabilization of sand dunes

and in stabilizing the desert

in western India.

Conservation of soil can be done several ways. Planting trees helps. Trees prevent erosion both with their roots and by blocking wind. Terracing is another good way to conserve soil. Terracing is leveled sections used for hilly farm lands. Tilling and plowing helps prepare soil for plants to grow, but it is promotes erosion, so finding ways to limit how much you till and plow will help.

- SOIL AND WATER CONSERVATION ENGINEERING BOOKBY . R.SURESH

- INTERNET