Brooks and Corey (1964) Estimation

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SVSoils

 

 

Brooks and Corey (1964) proposed a permeability function for predicting the unsaturated coefficient of permeability. The estimation method is based on a fit of the soil-water characteristic curve with the Brooks and Corey (1964) SWCC equation. The Brooks and Corey equation has been implemented in SVLUX in its original form.

 

k minimum:

The k minimum value entered in this field represents the minimum allowable hydraulic conductivity. The minimum hydraulic conductivity will be forced horizontal at this value. An absolute minimum value is at 1e-14 m/s at which vapour flow dominates the problem. When selecting the minimum value it is important to note that significant increases in the number of nodes may be required if the minimum hydraulic conductivity is less than 1e-10 m/s. It is therefore recommended that a minimum value of 1e-10 m/s be entered for most practical problems. The user is then encouraged to slowly reduce this value until the model fails to solve.

 

Apply k minimum:

The equation originally presented by van Genuchten (1980) did not have a limitation on the minimum hydraulic conductivity allowable. Applying a reasonable minimum to the unsaturated portion of the curve and dramatically improve numerical computations.

 

Corey Predicted:

The Corey Predicted field indicates if the fit algorithm has been successfully executed on the current data.

 

Corey Error:

The Corey Error is the difference between the fit and laboratory values in terms of R2.

 

Estimate

The Estimate button is provided at the bottom of the dialog in order to allow the user to estimate the hydraulic conductivity.

 

Graph:

The graph button allows the user to display a graph of suction versus hydraulic conductivity. The interpolated curve will also be displayed. It is important to note that laboratory data will be interpolated on an arithmetic scale.