Module PorousMedia

Other Features

How to Generate Info needed in Porous Media

SoilMap

Model needs to know soil ID in each cell and layer to pick hydraulic properties from that type of soil.

Options:

• Constant value
• Soil Grid. One possible option is to associate with soil shape file. In this case can use MOHID GIS going to menu [Tools]->[Shape to Grid Data] and provide: i) the grid (model grid), ii) the soil shape file and iii) the corespondence between soil codes and soil ID defined in data file.

Soil ID must be defined in Module FillMatrix standards for each soil horizon defined (grid example):

<beginhorizon>
KLB                       : 1
KUB                       : 10

<beginproperty>
NAME                      : SoilID
DEFAULTVALUE              : 1
INITIALIZATION_METHOD     : ASCII_FILE
REMAIN_CONSTANT           : 1
FILENAME                  : ..\..\GeneralData\PorousMedia\SoilID200m.dat
<endproperty>

<beginproperty>
<endproperty>
..
<endhorizon>

Remarks All the soil ID's appearing in the soil grid(s) must be defined in the PorousMedia data file in terms of hydraulic properties:

<beginsoiltype>
ID                        : 1
THETA_S                   : 0.3859
THETA_R                   : 0.0476
N_FIT                     : 1.39
SAT_K                     : 3.5556e-6
ALPHA                     : 2.75
L_FIT                     : 0.50
THETA_CV_MIN              : 0.2844
THETA_CV_MAX              : 0.3791
<endsoiltype>

<beginsoiltype>
ID                        : 2
...
<endsoiltype>
...

Soil Bottom

The soil depth must be known by the model. This is computed by the model from terrain altitude (topography) and soil bottom altitude. As so, a soil bottom grid is needed.

Options:

• Grid File.

Soil bottm altitude should be obtained from field data. If no data is available, soil depth (and soil bottom altitude, the effective grid needed) can be estimated from slope HOW TO SoilBottom LINK.

Define the grid generated in the porous media data file with:

BOTTOM_FILE  : ..\..\GeneralData\PorousMedia\BottomLevel.dat

Water Level

Options:

• Grid File.

The water table altitude should be obtained from field data. However, if no field data is available it is recommended to do a spin-up run to estabilize water level and then use the result as the water level input. Use the following blocks with Module FillMatrix standards:

<beginwaterlevel>
NAME                      : waterlevel
INITIALIZATION_METHOD     : ASCII_FILE
DEFAULTVALUE              : 0
REMAIN_CONSTANT           : 0
FILENAME                  : ..\..\GeneralData\PorousMedia\WaterLevel0.50.dat
<endwaterlevel>

Impermeability

Impermeability values (0 - completely permeable, 1 - impermeable) must be provided.

Options:

• Constant Value.
• Grid File. One possible option is to associate with land use shape file. In this case can use MOHID GIS going to menu [Tools]->[Shape to Grid Data] and provide: i) the grid (model grid), ii) the land use shape file and iii) the corespondence between land use codes and Impermeability values.

Use the following blocks with Module FillMatrix standards:

<beginimpermeablefraction>
NAME                      : impermeablefraction
INITIALIZATION_METHOD     : ASCII_FILE
DEFAULTVALUE              : 0
REMAIN_CONSTANT           : 1
FILENAME                  : ..\..\GeneralData\PorousMedia\AreaImpermeavel.dat
<endimpermeablefraction>

Data File

Sample

Some keywords of the PorousMedia input file:

<beginsoiltype>

• Saturated water content

THETA_S                   : 0.55

• residual water content

THETA_R                   : 0.1

• N of Van Genuchten: 1.5(clay) to 4.5 (sandy)

N_FIT                     : 1.15

+Saturated hydraulic conductivity

SAT_K                     : 1.39e-8

• alpha of Van Genuchten: 0.005 (clay) - 0.035 (sandy)

ALPHA                     : 0.02

• L of Mualem - Van Genuchten (mostly 0.5)

L_FIT                     : 0.50

<endsoiltype>