Properties

Properties

Fraction name

Each fraction is identified by a user-defined name.

Sediment type

The choice between cohesive or non-cohesive fraction type is selected from this list.

Porosity

The porosity of the sediment fraction. Porosity of the bottom sediment is usu­ally in the range of 0.3 to 0.7.

Relative density

The relative density of the sediment fraction, compared to water density (r_solid/r_water ). Thus, for sand, a typical value is 2.65.

Critical Shields parameter

The initiation of particle movement depends on the Critical Shields Parame­ter, q_CR.

Fall velocity definition

The fall velocity can either be user-defined or can automatically be computed using the Rubey formula.

Fall velocity value

When using a user-defined fall velocity, the corresponding value is entered here. When applying the Rubey formula, this displays the automatically cal­culated value.

Grain size

Global value

A global grain size value, which is applied throughout all calculation points in the river network, unless local values have been defined.

Local values

Local grain size values can only be specified for single-fraction models. Local grain size values are applied at specific locations defined by Branch name and Chainage.