Water Erosion

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Water Erosion “It is the detachment, transportation & deposition of soil particles by the force of water from one place to another.” “It is the movement of soil by rain water including melted snow, running rapidly over exposed land surfaces.”

description

Water Erosion. “It is the detachment, transportation & deposition of soil particles by the force of water from one place to another.” “It is the movement of soil by rain water including melted snow, running rapidly over exposed land surfaces.”. Factors Affecting Water Erosion. 1. Climate. - PowerPoint PPT Presentation

Transcript of Water Erosion

Page 1: Water Erosion

Water Erosion

“It is the detachment, transportation & deposition of soil particles by the force of water from one place to another.”

“It is the movement of soil by rain water including melted snow, running rapidly over exposed land surfaces.”

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Factors Affecting Water Erosion

1. Climate.

Precipitation Temperature Wind Humidity Solar radiation

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2. Soil

Physical properties of soil such as texture, structure etc.

Organic matter contents in soil. Moisture contents in soil. Soil density or compactness. Chemical and biological characteristics.

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3. Vegetation

Reduce rain drop velocity. Resist runoff Increase infiltration Enhance microbial activity. Improve soil structure.

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4. Topography.

Degree of slope of an area Length of slope of an area Size and shape of water shed

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Forms of Water ErosionForms of Water Erosion

Raindrop or Splash Erosion:Raindrop or Splash Erosion: Result from the impact of water drop directly on the Result from the impact of water drop directly on the

soil particles or thin water surfaces.soil particles or thin water surfaces. Splash losses are 50-90 times greater than the wash Splash losses are 50-90 times greater than the wash

off losses.off losses. On bare soil 224 Mg haOn bare soil 224 Mg ha-1-1 is splashed into air due to is splashed into air due to

heavy rains. heavy rains. It is first stage of water erosion. It is first stage of water erosion. Raindrops can be a major problem for farmers when Raindrops can be a major problem for farmers when

they strike bare soil. they strike bare soil. Soil particles can jump up to 2.5 feet.Soil particles can jump up to 2.5 feet.

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The relationship between erosion and rainfall momentous and energy is determined by

i. Rain drop size

ii. Mass

iii. Size distribution

iv. Shape

v. Velocity

vi. Direction

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Energy equation has been developed by Wischmerer & Smith (1958) is:

E = 12.1 + 8.9 log i

E = Kinetic energy in Mg ha-1

i = intensity in mm h-1

Factors affecting direction & distance of soil splash are:

i. Shape

ii. Wind

iii. Surface condition

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Raindrop ErosionRaindrop Erosion

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Sheet Erosion Sheet Erosion

Uniform removal of soil in thin layers from sloping Uniform removal of soil in thin layers from sloping land.land.

Occurrence is rare.Occurrence is rare. In reality the loose soil merely runs off with the rain.In reality the loose soil merely runs off with the rain. The beating action of raindrops combined with The beating action of raindrops combined with

surface flow causes initial microscopic rilling.surface flow causes initial microscopic rilling. From energy point of view, raindrop erosion is more From energy point of view, raindrop erosion is more

important because raindrops have velocities of 6-9 important because raindrops have velocities of 6-9 msms-1-1 (20-30 fs (20-30 fs-1-1) whereas overloaded flow velocities ) whereas overloaded flow velocities are about 0.3-0.6 msare about 0.3-0.6 ms-1-1 (1-2fs (1-2fs-1-1).).

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Sheet ErosionSheet Erosion

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Rill ErosionRill Erosion

Transitional phase between sheet erosion and Transitional phase between sheet erosion and gully erosion gully erosion

Its effects can be easily removed by tillageIts effects can be easily removed by tillage It occurs when soil is removed by water from It occurs when soil is removed by water from

little streamlets that run through land with little streamlets that run through land with poor surface drainingpoor surface draining

Rills can often be found in between crop rows Rills can often be found in between crop rows

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Rill ErosionRill Erosion

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Gully ErosionGully Erosion

It is last stage of water erosion. It is last stage of water erosion. Gullies are larger than rills and cannot be fixed by Gullies are larger than rills and cannot be fixed by

tillage.tillage. Gully erosion is an advanced stage of rill erosion.Gully erosion is an advanced stage of rill erosion. Major concentrations of high-velocity run-off water Major concentrations of high-velocity run-off water

in these larger rills remove vast amounts of soil.in these larger rills remove vast amounts of soil. This results in deeply incised gullies occurring along This results in deeply incised gullies occurring along

depressions and drainage lines.depressions and drainage lines.

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Gully ErosionGully Erosion

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Stream Erosion.Stream Erosion.

When water flow in gullies become When water flow in gullies become permanent, it is called a stream which may be permanent, it is called a stream which may be permanent or seasonal is called as stream permanent or seasonal is called as stream

erosionerosion..

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Areas of Water Erosion

Nothern Hilly Areas Pothwar Pleatue Foothills of Himalayas in Punjab Western hilly Areas

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Damages of Water Erosion

Loss of soil specially fertile layer Low fertile soil decrease farmer income Remove organic matter from the soil Decrease infiltration capacity of soil Increase runoff Increase flood hazard Damage the wild life fisheries etc Fill up the streams and dams

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Mechanism of Water ErosionMechanism of Water Erosion

A. A. DetachmentDetachment.:.: it is first to occur and is it is first to occur and is independent variable. Soil clods are broken independent variable. Soil clods are broken into small particles.into small particles.

B.B. Transportation Transportation.:.: it is dependent variable and it is dependent variable and depends upon detachment.depends upon detachment.

C.C. Deposition Deposition:: is dependent variable and depend is dependent variable and depend upon detachment and transportation.upon detachment and transportation.