Carlos Andres Rivera Villarreyes Global Product Specialist - FEFLOW

Two more alternatives (in case analysis should be done varying material properties):

1) Use FePEST in the command line mode to setup a SENSAN (Sensitivity Analysis) run using PEST. Here you can define the parameter to be modified and distribute the output results in different files. It may require some time until to get into the workflow, but then it is worthy since you can have additional feedbackfrom PEST, which may help you to understand the sensitivity analysis.

2) Download the old FEFLOW-specific groundwater utilities for PEST. There is a nice routine named FMAINFEM to assign automatically material values to a FEM file directly in the windows command line. This was used in the past to run PEST with FEFLOW, now with the FePEST interface is not required anymore. Link is http://www.feflow.com/miscellaneos.html

Sure. You need to define adequate parameters for the unsaturated flow modelling carried out by the Richards equation. This means you need an empirical model to relate saturation and negative pressure, saturation limits, etc. By the way, analogous to the residual water depth in the Phreatic approach, you will also need to setup an adequate residual saturation limit proper for the material properties.

Hi Michael,

"Pending" means that FEFLOW cannot retrieve primary variables values to compute the budget. You just need to start the simulation.
If you save the DAC file using the Record Properties option at the simulation toolbar, you can have all the entire model results to compute any kind of budget.

Cheers,

Carlos

There are two alternatives:

1) Create Observation Points at specific locations and connect them to the reference values. Then go to View - Chart - Hydraulic Head History and you will have the simulated and "reference" heads. Scatter plot is also available. You can find a lot of information how to add Observation Points in the Help System.

2) Export the FEFLOW simulated hydraulic heads. Simply a right-click on Hydraulic Head and the Export Data. You can export values from either all nodes or nodal selection.

Hi,

The slices below should be indicated as "Dependent". The "free" first slice will move according to the fluctuations of the phreatic level. Here, pressure will be always zero and FEFLOW will adjust the slice elevation to fulfill the statement. The next slices are adapted to changes of free slice.
I would recommend you to take a look on White Paper I (http://www.feflow.info/manuals.html) for further details.

Cheers,

Carlos

Dear Perl,

Personally I believe there is not an exact rule for deciding about interpolation techniques. The selection depends on many variables such as data type, data transformation, distribution of your points, geometry of domain, etc. These last two are the most critical. I think the best way is a trial-and-error approach here. You can make double-check plotting both interpolated fields and measurements at the same view.

Regards,

Carlos

Hi,

FEFLOW has been tested with several benchmark exercises. One of them is the Theis' solution. You may take a look on the section 9.8.1 "[i][b]Transient Flow to a Well in a Confined and Unconfined Aquifer[/b][/i]" in the FEFLOW Book (pages 429-435).

Regards,

Carlos

Dear Giuseppe,

Alternatively, you can edit the multilayer wells directly on the FEFLOW interface. Steps: 1) select the multilayer well, 2) go to the View Components panel, 3) activate Multilayer Well - Attributes, and 4) activate ONLY the attribute to edit.
You will notice that Editor toolbar will change to the attribute, e.g. "Rate (MLW)". Here you can just type the new value.

Two additional ways if you have several multilayer wells,

a) Use Link to Parameter (s) option in the Map panel to make the MLW assignment. Here, you can create a table (excel, text file, etc.) with all the attributes and link values to MLW. If edition is needed, you can edit your table any time (outside of FEFLOW) and then re-create the link again.

b) [b]This is the very fast option![/b] ONLY available in FEFLOW 6.2.
- Export all the values of MLW. Data panel and right-click on Multilayer Well. Here you can use a Excel file, text file, etc.
- Edit your tables
- Import your map file again
- In the Map panel, right-click on re-imported map and choose [b]Quick Import[/b]

[b]Quick Import[/b] option will make the assignment automatically. No further action is required here. The trick is that every time you export FEFLOW information, you have also values of node and element numbers. Therefore if you did not modify this topology, the Quick Import will know where exactly to place the assignment again. Operation is valid for nodal and elemental assignments.

Cheers,

Carlos

Dear Debora,

If you are looking for a mathematical formation, which expresses the non-linearity between saturation and pressure, then I would recommend you to switch to the Richards-equation in FEFLOW. Here you will need to apply an empirical model, e.g. van Genuchten, to describe reduction of conductivity and others behaviors.

About the residual water depth, this could be interpreted as the residual water content. In some Soil Physics books, you will find that saturation can be expressed as the so-called saturation length or saturation depth. If you take an one-meter soil column and you include only the residual water content into it, the column of water inside this container is named residual water depth.

Cheers,

Carlos

Dear Ludwig,

A non-reactive tracer does not mean that dispersivity values should be zero. The conservative tracers do not consider chemical reaction (degradation rate) and solute interchange between solid and liquid phases (i.e. adsorption). In Groundwater literature, one typically speaks about the [b]retardation coefficient[/b] in order to distinguish between reactive and conservative tracers, you may be interested to read about this.
The selection of convective and dispersive mass transport formulations in FEFLOW depends on model boundary conditions. You may take a look on White Papers Vol. I.

In addition, I recommend you the following things:
1) Try using a 3rd kind BC to simulate the interaction river-aquifer. Here you can indicate low values of conductance (transfer rates) to account for clogging effect.
2) If you want to delineate hyporheic zone, you can use the new class [b]AGE [/b] introduced recently in FEFLOW 6.2. For example, 1) a so-called [b]"age"[/b] specie can be used to identify the mixture zones of two water bodies with different origins; and 2) apply the so-called [b]"exit"[/b] specie to delineate the capture zone of the river boundary.

Cheers,

Carlos