# Sediment transport

### Generalities

The calculation of sediment exchanges involves three steps:

• Calculating an equilibrium concentration according to a proposed law;
• Calculating an adaptation time following of Han’s formula or Hazen’s formula: where is the fall velocity;
• Calculation of the exchange term ;
where and are dimensionless parameters.

The fall rate is calculated according to Zanke’s formula:

This law is equal to Stokes’ law for small diameters, and Newton’s law for larger particles.