Question

The minimum wind velocity at 0.30 m from ground surface required to initiate the movement of the most erodible soil particle is about:

• A. 22 km/h
• B. 18 km/h
• C. 12 km/h
• D. 10 km/h

Hint:

Wind erosion is initiated at a "threshold velocity," which is lowest for fine sand particles (around 0.1 mm). Smaller particles (silt, clay) are more cohesive and require stronger winds, while larger particles are too heavy to be moved easily.

Answer 1

The Correct Option is B

Step 1: Establish the threshold velocity for wind erosion. Threshold velocity is defined as the lowest wind speed necessary to cause soil particle movement. Soil characteristics such as texture, moisture content, and surface roughness influence this velocity.
Step 2: Specify the characteristic threshold velocity for susceptible soils. Fine sands, with particle diameters generally ranging from 0.1 to 0.15 mm, are the most erodible. Research and field data indicate that wind erosion initiates for these particles when the wind speed at a height of 30 cm (0.3 m) reaches approximately 18 km/h (or roughly 5 m/s). This figure is commonly recognized in soil science and erosion research.