1. 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.”

2. Factors Affecting Water Erosion
1. Climate.
Precipitation
Temperature
Wind
Humidity
Solar radiation

3. 2. Soil Soil density or compactness.
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.

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

5. 4. Topography.
Degree of slope of an area
Length of slope of an area
Size and shape of water shed

6. Forms of Water Erosion Raindrop or Splash Erosion:
Result from the impact of water drop directly on the soil particles or thin water surfaces.
Splash losses are times greater than the wash off losses.
On bare soil 224 Mg ha-1 is splashed into air due to heavy rains.
It is first stage of water erosion.
Raindrops can be a major problem for farmers when they strike bare soil.
Soil particles can jump up to 2.5 feet.

7. The relationship between erosion and rainfall momentous and energy is determined by
Rain drop size
Mass
Size distribution
Shape
Velocity
Direction

8. Energy equation has been developed by Wischmerer & Smith (1958) is:
E = log i
E = Kinetic energy in Mg ha-1
i = intensity in mm h-1
Factors affecting direction & distance of soil splash are:
Shape
Wind
Surface condition

9. Raindrop Erosion

10. Sheet Erosion
Uniform removal of soil in thin layers from sloping land.
Occurrence is rare.
In reality the loose soil merely runs off with the rain.
The beating action of raindrops combined with surface flow causes initial microscopic rilling.
From energy point of view, raindrop erosion is more important because raindrops have velocities of 6-9 ms-1 (20-30 fs-1) whereas overloaded flow velocities are about ms-1 (1-2fs-1).

11. Sheet Erosion

12. Rill Erosion
Transitional phase between sheet erosion and gully erosion
Its effects can be easily removed by tillage
It occurs when soil is removed by water from little streamlets that run through land with poor surface draining
Rills can often be found in between crop rows

13. Rill Erosion

14. Gully Erosion It is last stage of water erosion.
Gullies are larger than rills and cannot be fixed by tillage.
Gully erosion is an advanced stage of rill erosion.
Major concentrations of high-velocity run-off water in these larger rills remove vast amounts of soil.
This results in deeply incised gullies occurring along depressions and drainage lines.

15. Gully Erosion

16. Stream Erosion.
When water flow in gullies become permanent, it is called a stream which may be permanent or seasonal is called as stream erosion.

17. Areas of Water Erosion Nothern Hilly Areas Pothwar Pleatue
Foothills of Himalayas in Punjab
Western hilly Areas

18. 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

19. Mechanism of Water Erosion
A. Detachment.: it is first to occur and is independent variable. Soil clods are broken into small particles.
B. Transportation.: it is dependent variable and depends upon detachment.
C. Deposition: is dependent variable and depend upon detachment and transportation.