Sediment transport

Generalities

The calculation of sediment exchanges involves three steps: - Calculating an equilibrium concentration \(C_{eq}\) according to a proposed law; - Calculating an adaptation time following of Han’s formula \(t_A=\beta\frac{Ru*}{VW}\) or Hazen’s formula: \(t_A=\beta\frac{R}{W}\) where \(W\) is the fall velocity; - Calculation of the exchange term \(E=\frac {\alpha C_{eq}-C }{t_A}\) ; where\(\alpha\) and\(\beta\) are dimensionless parameters.

The fall rate is calculated according to Zanke’s formula: \[W=1.1*10\frac{\nu}{d}\left(\sqrt{1+\frac{0.01 g (\rho_S/\rho-1)d^3}{\nu^2}}-1\right)\] This law is equal to Stokes’ law for small diameters, and Newton’s law for larger particles.