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 depth (and soil bottom altitude, the effective grid needed) can be defined with a constant depth or estimated from slope HOW TO SoilBottom LINK.

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

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

Water Level

Options:

• Grid File.

The water table altitude represents the initial altitude of the water table. It is recommended to do a spin-up run to estabilize water level and then do a continuous simulation starting with the final water table achieved. 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

Keywords

Keywords read in the Data File

Keyword                   : Data Type         Default     !Comment

BOTTOM_FILE               : char              -           !Path to Bottom Topography File
START_WITH_FIELD          : logical           1           !Sets Theta initial Field Capacity
CONTINUOUS                : logical           0           !Continues from previous run
STOP_ON_WRONG_DATE        : logical           1           !Stops if previous run end is different from actual
                                                          !Start
OUTPUT_TIME               : sec. sec. sec.    -           !Output Time
TIME_SERIE_LOCATION       : char              -           !Path to File which defines Time Series
CONTINUOUS_OUTPUT_FILE    : logical           1           !Writes "famous" iter.log
CONDUTIVITYFACE           : integer           1           !Way to interpolate conducivity face
                                                          !1 - Average, 2 - Maximum, 3 - Minimum, 4 - Weigthed
HORIZONTAL_K_FACTOR       : real              1.0         !Factor for Horizontal Conductivity = Kh / Kv
CUT_OFF_THETA_LOW         : real              1e-6        !Disables calculation when Theta is near ThetaR
CUT_OFF_THETA_HIGH        : real              1e-15       !Set Theta = ThetaS when Theta > ThetaS - CUT_OFF_THETA_HIGH
MIN_ITER                  : integer           2           !Number of iterations below which the DT is increased
MAX_ITER                  : integer           3           !Number of iterations above which the DT is decreased
LIMIT_ITER                : integer           50          !Number of iterations of a time step (for restart)
THETA_TOLERANCE           : real              0.001       !Converge Parameter
INCREASE_DT               : real              1.25        !Increase of DT when iter < MIN_ITER
DECREASE_DT               : real              0.70        !Decrease of DT when iter > MAX_ITER

<beginproperty>
NAME                      : Theta / waterlevel 

see Module FillMatrix for more options

<endproperty>

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>