Land Resources and reasons for land degradation

1. Land Resources
Presented by
Dr.ShwetaYaragatti
AssistantProfessor
DepartmentofDravyaguna
1
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November 4,2022

2. Land as a Resource
✧ The most important natural resource, upon which all human
activity is based since time immemorial, is land.
✧ Land resource is our basic resource.
✧ Throughout history, we have drawn most of our sustenance and
much of our fuel, clothing and shelter from the land.
✧ It is useful to us as a source of food, as a place tolive, work and
play. It is a productive economic factor in agriculture, forestry,
grazing, fishing and mining.
✧ It is considered as a foundation of social prestige and is the basis
of wealth and political power

4. Land Degradation
✧ Humanity’s progress towards development has,however,
considerably damaged our land resource base, probably since the
dawn of civilization.
✧ Out of the total land area, as many as 175million hectares suffer
from degradation.
✧ Land degradation is caused largely by soil erosion, but also by
water logging and excessive salinity.
✧ The most serious threat to the land is posed by deforestation.

5. contd..
✧ The exponentially growing population in the country has placed
immense pressure on the dwindling land resources, endangering the
very survival of the biome as a whole.
✧ The high degree of degradation of existing land resources, the
changing climate and increasing diversion of land from agricultural to
non-agricultural uses have aggravated the problem.
✧ Consequently, the productivity of land has suffered to a great extent,
sometimes beyond repair and per capita arable land is also
decreasing with the progress of time.
✧ India, being a large agrarian society, has, therefore,an enormous task
to meet the growing demands for food, fuel, fiber together with
environmental security for its people in the coming years

6. Soil Erosion
✧ The top soil is precious to all living beings.
✧ The top soil is being continuously eroded by the different natural
agents like air and water.
✧ Accelerated erosion is due to overgrazing,deforestation, mining
✧ Naturally,two types of agents cause soil erosion: water and Wind

7. Accelerated Erosion- Overgrazing

8. Accelerated Erosion- Mining

9. Accelerated Erosion- Deforestation

10. Water Induced Erosion
✧ SheetErosion
✧ RillErosion
✧ GulliesorGullyErosion
-SlipErosion
-StreambankErosion

11. Sheet Erosion
✧ Water moving fairly uniformly with a similar thickness over a
surface is called sheet flow, and is the cause of sheet erosion.
✧ Sheet erosion implies that any flow of water that causes the erosion
is not canalized.
✧ One example of sheet erosion is when loose soil that covers a hill is
washed down a slope by rainwater that flows consistently.
Another example of sheet erosion is when a layer of soil that was
freshly plowed or evened out starts to erode evenly from a flow of
water

12. Rill and Gully Erosion
✧ Rill erosion occurs when runoff water forms small channels
as it concentrates down a slope.
✧ These rills can be up to 0.3m deep. If they become any
deeper than 0.3m they are referred to as gully erosion.

13. Rill erosion

14. Gully erosion

15. ✧ GULLIES ARE LARGER THAN RILLS AND CAN
NOT BE FIXED BY TILLAGE.
✧ GULLY EROSION IS AN ADVANCED STAGE
OF RILL EROSION, JUST AS RILLS ARE
OFTEN THE RESULT OF SHEET EROSION

16. Slip erosion
✧ Slip erosion is a natural disaster that causes the land of a higher
area to slip and fall on a lower surface.
✧ It is a mass movement or slope movement by which soil, rock, etc
move down slope mainly under the force of gravity.
✧ The phenomenon of the landslide is also known as slip erosion.

17. SlipErosion

18. Stream bank Erosion
✧ Bank erosion is the wearing away of the banks of a stream or
River.
✧ This is distinguished from erosion of the bed of the watercourse,
which is referred to as scour.
✧ The roots of trees growing by a stream are undercut by such
erosion.
✧ As the roots bind the soil tightly, they form abutments which jut out
over the water.

19. Streambankerosion

20. Wind Erosion
✧ Wind erosion, unlike water, cannot be divided into such distinct
types. Surface texture is the best key to wind erosion hazard
potential.
✧ Its responsible for 3 types of soil movements
• Saltation
• Suspension
• Surface Creep

21. Wind Erosion- Saltation
✧ In geology, saltation is a specific type of particle transport by
fluids such as wind or water.
✧ It occurs when loose materials are removed from a bed and
carried by the fluid, before being transported back to the
surface.

22. Wind Erosion- Suspension
✧ Suspension - The finer sand particles are moved by the wind, high
in the air. They are not affected by gravity and therefore can travel
thousands of kilometers before they land on earth again.
✧ tiny particles less than 0.1 mm in diameter can be moved into the
air by saltation, forming dust storms when taken further upwards
by turbulence.
✧ These particles include very fine grains of sand, clay particles and
organic matter.

23. Wind erosion - Surface Creep or Creep
✧ It is a wind erosion process in which sand grains are moved along
the ground surface by impact of other grains in saltation.
✧ In a wind erosion event, large particles ranging from 0.5 mm to 2
mm in diameter, are rolled across the soil surface.
✧ This causes them to collide with, and dislodge, other particles.
Surface creep wind erosion results in these larger particles moving
only a few metres.

24. Wind Erosion

25. Landslides
✧ In this, huge masses of land, slide down ,destroying anything
in their path.
✧ Man made activities such as various developmental activities
like large dams,reservoirs, construction of roads etc require
large scale deforestation.
✧ This increases chances of landslides.
✧ Apart from that, mainly there are
Earthquake induced Landslides and
Rain induced Landslides.

26. Earthquake Induced Landslides(EIL)
• When an earthquake occurs, the transmission of seismic waves can
cause shaking and vibration of ground surface.
• This often trigger the collapse of potential landslide areas, which is
known as earthquake-induced landslide.
The landslides that occurred during this earthquake can be roughly
classified into three types
the rock falls,
the landslides with long-distance travel in the volcanic cohesive soil
slopes,
the settlement and flow of the artificial slopes.

27. Rainfall Induced Landslides(RIL)
✧ It was concluded that due to heavy rainfall matric suction in
unsaturated part of slope is lowered.
✧ As the water starts infiltrating in the soil negative pore pressure
dissipates due to increase water content in soil.
✧ This decreases the shear strength parameters in soil layers close to
the surface which caused failure.
✧ And thus , a landslide occurs because of such cascading layers of soil.

28. contd..
✧ Rainfall-induced landslides (RILs) are natural hazards that
generate a large number of casualties and economic losses every
year.
✧ Rainfall, soil, and slope play a key role in RIL genesis that must
be evaluated in each case.
✧ Despite RIL research in recent years, RILs cannot be avoided.
✧ Rainfall-induced landslide early warning systems (RILEWSs) be-
come a powerful alternative for mitigating human losses and
reducing infrastructure damage.

29. Landslides

30. Desertification
✧ Process of conversion of productive land to arid or semi arid
lands
✧ 10-25% drop in productivity in moderate desertification
✧ More than 50% in serious desertification
✧ Creates gullies or sand dunes
✧ Leads to depletion of ground water, salinization

31. contd..
✧ Causes are deforestation, overgrazing and mining
✧ Areas include Saharan Africa, Middle East,Western Asia,
parts of central and south America.
✧ Domino effects are observed.

32. Desertification

33. Water Logging and Salinity
✧ Result of excessive irrigation
✧ Pore spaces filled with water
✧ Roots cannot breathe
✧ Make continuous column with water.
✧ When water evaporates leaves behind a white crust of salt.
✧ And it is Extremely high in sodium quantity.
✧ Precious LAND RESOURCE IS WASTED, resulting in
desertification.

34. Discussion....

35. References
✧ Wikipedia-www.wikipedia.org
✧ DepartmentofLandResources,GovernmentofIndia-
www.dolr.gov.in
✧ Slideshare-www.slideshare.net
✧ Andfinally,Google.

36. Thank You!!