Initialisation

Initialisation from site input

The following parameters are initialized:

Saturated and residual water content

Saturated and residual water content are taken from site-specific inputs when available. If not provided, defaults are assigned based on soil texture. Texture is determined per layer from sand, clay, and silt fractions. If texture cannot be estimated, the general soil type is used instead. For humus layers, humus-type-specific default values are applied.

Field capacity and wilting point

Field capacity (FC) and wilting point (WP) can be provided directly, derived from van Genuchten parameters, or taken from soil-type-specific defaults. If only FC/WP provided, they will be used. If van Genuchten parameters are provided, FC/WP will be determined based on their values.

If neither van Genuchten parameters nor FC/WP are provided, the model uses a pedotransfer function if organic carbon and bulk density are given. If not, the soil-type-specific default value is used.

After determination, of FC/WP, WP is checked for consistency against FC, i.e., WP is not allowed to exceed 90% of estimated FC:

\( \theta_{wp} = min(\theta_{wp}, 0.9 \; \theta_{fc}) \)

Macropores

Macropores are taken from site-specific inputs when available. If not provided, defaults are assigned based on soil texture. Texture is determined per layer from sand, clay, and silt fractions.

Saturated hydraulic conductivity

Saturated hyraulic conductivity is taken from site-specific inputs when available. If not provided, defaults are assigned based on soil texture. Texture is determined per layer from sand, clay, and silt fractions.

Van Genuchten parameters

Van Genuchten parameters can be provided directly, derived from field capacity and wilting point, or taken from soil-type-specific defaults.