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Wind erosion
- 1. Wind Erosion By: Shahab Ud Din, Tariq Abdullah To: Dr. Ashraf 1 Shahab Ud Din
- 2. C o n t e n t s D e f i n i t i o n E f f e c t s o f w i n d e r o s i o n C o n t r i b u t i n g f a c t o r s M e c h a n i s m T y p e s o f e r o s i o n C o n t r o l m e a s u r e s 2 Shahab Ud Din
- 3. “ ” Detachment and movement of soil material by the action of wind WIND ERO SIO N Wind erosion is a common cause of land degradation in the arid and semi arid 3 Shahab Ud Din
- 4. E f f e c t s o f w i n d e r o s i o n S o i l f e r t i l i t y E x p o s e d e n s e c l a y s u b s o i l s S a n d b l a s t i n g A i r p o l l u t i o n 4 Shahab Ud Din
- 5. Soil fertility Soil fertility is reduced because of the loss of the plant nutrients that are concentrated on fine soil particles and organic matter in the topsoil. This reduces the soils capacity to support productive pastures and sustain biodiversity. 5 Shahab Ud Din
- 6. Expose dense clay subsoils The erosion of light-textured topsoil can expose dense clay subsoils. These smooth and bare areas, called claypans or scalds can cover hundreds or even thousands of hectares. They are difficult to revegetate due to the lack of topsoil, low permeability and their often saline nature. 6 Shahab Ud Din
- 7. Sandblasting Sand grains transported by strong winds can damage vegetation in their path by sandblasting. Shahab Ud Din 7
- 8. Air pollution Air pollution caused by fine particles in suspension can affect people's health and cause other problems. 8 Shahab Ud Din
- 9. C o n t r i b u t i n g f a c t o r s Wind speed & duration Soil properties Land surface factors Overgrazing by livestock Periods of drought breakdown of the biological soil crust 9 Shahab Ud Din
- 10. Wind speed & duration Wind speed of which have develop the relationship with the rate of soil erosion caused by the action of wind The wind speed required for erosion depends on the size, weight and wetness of the soil particles. The wind is about 16km/h at a hight of 30cm above the land, required for significant erosion to occur. 10 Shahab Ud Din
- 11. Soil properties Wind erosion is inversely proportional to structural stability. As structural stability increases, chances of wind erosion decreases. As OM increases structural stability increases, thus decrease in wind erosion As SOIL MOISTURE increases structural stability increases, thus decrease in wind erosion Among all, sandy texture having lower structural stability. 11 Shahab Ud Din
- 12. Land surface factor Improves the roughness of land decrease wind erosion Presence of vegetative cover decrease wind erosion In flat topography, more air flow, so more wind erosion In contour topography, less air flow, so low wind erosion More tree plantation, results in lower wind speed and hence, low wind erosion. 12 Shahab Ud Din
- 13. Overgrazing by livestock Overgrazing by livestock is a prime cause of wind erosion. Grazing pressure can also occur from kangaroos and wallabies, as well as feral animals such as rabbits, goats and camels Wind erosion occurs due to loss of vegetative cover. 13 Shahab Ud Din
- 14. Periods of drought Periods of drought associated with a negative impacts provide the highest levels of wind erosion activity Dominant in arid to Sami-arid conditions, due to low rainfall 14 Shahab Ud Din
- 15. Breakdown of the biological soil crust The breakdown of the biological soil crust, which is a characteristic of many arid zone soils, makes soils susceptible to wind erosion. This living crust incorporates algae, lichens, mosses and liverworts and protects the soil from all forms of soil erosion. Crust cover can take many years to recover once damaged 15 Shahab Ud Din
- 16. M e c h a n i c s o f w i n d e r o s i o n The loss of soil movement involves two processes. Detachment Transportation The lifting and abrasive action of wind results in detachment of tiny soil grains which apart. When the wind is laden with soil particles, however, its abrasive action is greatly increased. The impact of these rapid moving grains dislodges other particles from soil aggregates The transportation of the particles once they are dislodged take place in several ways 16 Shahab Ud Din
- 17. Abrasion process The basic mechanics of wind erosion 17 Shahab Ud Din
- 18. Types of erosion Saltation Surface creep Suspension 18 Shahab Ud Din
- 19. Saltation The bouncing or jumping of soil particles by the action of wind is known as saltation. The soil particles having the diameter 0.05mm to 0.5mm are moved as saltation 19 Shahab Ud Din
- 20. Surface creep It is rolling or sliding of soil particles along the soil surface by the action of wind Soil particles having diameter 0.5mm to 2mm are detached and moved by surface creep. 20 Shahab Ud Din
- 21. Suspension The floating of small particles n the air and there movement by the air. Particle size is less than 0.05mm 21 Shahab Ud Din
- 22. 22 Shahab Ud Din
- 23. C o n t r o l m e a s u r e s Wind breaks Vegetative cover Mulching Cropping system Soil moisture conservation Tillage operations 23 Shahab Ud Din
- 24. Wind breaks Any barrier placed perpendicular to direction of wind will help to reduce wind speed near ground level and consequently reduces wind erosion 24 Shahab Ud Din
- 25. Vegetative cover It protect the soil against direct striking by wind. So, vegetative cover reduce the wind speed and reduce the wind erosion 25 Shahab Ud Din
- 26. Mulching Mulching of soil organic or synthetic material i.e. sugar straw and polethine sheet, reduce wind erosion by protecting against the direct striking the wind. It also conserve moisture. 26 Shahab Ud Din
- 27. Cropping system It should be such that soil should not be fellow at any time. Shallow and deep rooted crops should be cultivated Which improves soil structure and reduce the rate of wind erosion. 27 Shahab Ud Din
- 28. Soil moisture conservation It helps to improves the biological activities in the soil, Leading to an improve in soil structure Thus may reduce the rate of wind erosion. 28 Shahab Ud Din
- 29. Tillage operations Tillage operations should be perpendicular to the direction of wind. Which helps to reduce wind speed and consequently wind erosion. 29 Shahab Ud Din
- 30. Shahab Ud Din 30
- 31. Any Question 31 Shahab Ud Din
- 32. Thank you 32 Shahab Ud Din