Sediment Transport Calculator

Determine whether bed sediment moves using the Shields criterion for incipient motion.

Open Channel Flow · Sediment

Sediment material — sets ρ_s

Fluid — sets ρ

Inputs

Particle diameter d (mm)

Sediment density ρs (kg/m³)

Fluid density ρ (kg/m³)

Bed shear stress τ (Pa)

Theory

Shields Parameter:

τ^* = τ / [(ρ_s − ρ) × g × d]

τ_cr = θ_cr × (ρ_s − ρ) × g × d

Where:

τ = bed shear stress [Pa]
ρ_s = sediment density [kg/m³]
ρ = fluid density [kg/m³]
d = particle diameter [m]
θ_cr ≈ 0.047 for quartz sand in water (Shields 1936)
τ_cr = critical bed shear stress for incipient motion [Pa]
Mobility ratio τ^*/θ_cr > 1 → sediment moves; < 1 → bed stable

Sediment begins to move when τ^* > θ_cr. The critical Shields parameter depends on the particle Reynolds number Re_* = u_*d/ν and ranges from about 0.03 to 0.06 for typical sands.

Sediment Transport Calculator

Sediment material — sets ρs

Fluid — sets ρ

Inputs

Theory

Sediment Transport Calculator

Sediment material — sets ρs

Fluid — sets ρ

Inputs

Theory

Sediment material — sets ρ_s

Sediment material — sets ρ_s