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: Define threshold velocity in wind erosion. Threshold velocity is the minimum wind speed required to initiate movement of soil particles. This velocity depends on factors like soil texture, moisture content, and surface roughness.
Step 2: State the typical threshold velocity for erodible soils. The most erodible soil particles are fine sands, typically 0.1 to 0.15 mm in diameter. For these particles, scientific studies and field observations have shown that wind erosion begins when the wind velocity at a height of 30 cm (0.3 m) reaches about 18 km/h (or approximately 5 m/s). This is a widely accepted value in soil science and erosion studies.