Flow Properties

Note:The user may opt to use properties for one of 22 generic soil types. References to these soils can be obtained from the VS2DH documentation (Lappala and others, 1987). The soil types that are followed by "CP" were obtained from Carsel and Parrish, 1988, "Developing joint probability distributions of soil water retention characteristics", Water Resources Research, v. 24, p. 755-769. Another useful reference for unsaturated soil hydraulic properties is the UNSODA database of Agricultural Research Service, United States Salinity Lab: http://www.ussl.ars.usda.gov/MODELS/UNSODA.HTM

Flow properties common to all hydraulic characteristic functions:

Name: A descriptive title of the texture class.
Kzz/Khh: Ratio of saturated hydraulic conductivity in the vertical (z) direction to that in the horizontal (x or r) direction.
Saturated Khh: [L]/[T]. Saturated hydraulic conductivity in the horizontal (x or r) direction.
Specific Storage (Ss): 1/[L]. Fluid storage due to fluid and porous medium compressibilities under saturated conditions.
Porosity: Defined in the usual way--volume of pore space per bulk volume of soil or porous medium.

van Genuchten Model: (see formula)

RMC: Residual moisture content.
alpha: 1/[L]. Parameter in van Genuchten model. Must be positive. Note to VS2DH 1.0 users
beta: Parameter in van Genuchten function.

Brooks-Corey Model: (see formula)

RMC: Residual moisture content.
h_b: [L]. Air entry pressure head in Brooks-Corey model. Must be negative.
lambda: Pore-size distribution index.

Haverkamp Model: (see formula)

RMC: Residual moisture content.
A': [L]. Parameter in Haverkamp model. Must be negative.
B': Parameter in Haverkamp model.
alpha: [L] Parameter in Haverkamp model. Must be negative.
beta: Parameter in Haverkamp model.

Tabular Data: Consist of moisture content and relative hydraulic conductivity values for a range of pressure head values. See: Working with tabular data