Last reviewed 1 Oct 2026 · 6 min read
What is wind erosion?
Wind erosion is the detachment, transport and deposition of soil particles by wind. It is serious in arid and semi-arid regions where rainfall is low, vegetation is sparse and soils are dry, loose and finely textured. In India it is concentrated in western Rajasthan (Thar), parts of Gujarat, Haryana, Punjab and coastal strips.
Mechanics
Wind exerts drag and lift on soil grains; when the wind speed exceeds the threshold at the surface, grains begin to move.
Modes of soil movement
| Mode | Size of particle | Share of transport | Description |
|---|---|---|---|
| Saltation | About 0.1–0.5 mm (fine sand) | About 50–80 % | Grains bounce along the surface in short hops (to about 1 m high) — the main mode, which also knocks loose other grains (the "sandblast" effect) |
| Surface creep | About 0.5–2 mm | About 7–25 % | Larger grains roll or slide along the surface when struck by saltating grains |
| Suspension | Below about 0.1 mm (silt, clay, fine dust) | About 3–40 % | Fine dust lifts and travels long distances (dust storms) |
Saltation is the key: control it and most erosion stops.
Threshold velocity
- Wind speed needed to start movement at a height of about 30 cm is roughly 15–20 km/h (about 4–5.5 m/s), depending on soil. Once started, erosion increases with the cube of the speed above threshold.
- The most erodible sizes are about 0.1–0.15 mm (fine sand); soil aggregates or clods larger than about 0.84 mm are non-erodible (resist wind), which is why the erodible fraction is defined as particles less than 0.84 mm.
- Rough surfaces (ridges, clods, vegetation) lower the wind speed at the ground.
Wind-profile and friction velocity
Near the ground the wind speed varies as a logarithmic profile:
where = friction (shear) velocity, (von Kármán constant) and = roughness height. Bagnold's formula for the sand transport rate is
— it shows transport rises with the cube of the friction velocity and increases with grain size ( = standard grain size 0.25 mm).
For the same soil, a rise in the friction velocity from 0.4 m/s to 0.6 m/s (a factor of 1.5) increases the transport rate by times — a gust only 50 % stronger moves more than three times as much sand.