Model help:TopoFlow-Infiltration-Richards 1D: Difference between revisions
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<div id=CMT_MODEL_PARAMETERS> | <div id=CMT_MODEL_PARAMETERS> | ||
==Model parameters== | ==Model parameters== | ||
= | = Input = | ||
{|{{Prettytable}} class = "wikitable unsortable" cellspacing="0" cellpadding="0" style="margin:0em 0em 0em 0;" | {|{{Prettytable}} class = "wikitable unsortable" cellspacing="0" cellpadding="0" style="margin:0em 0em 0em 0;" | ||
|- | |- | ||
!Parameter!!Description!!Unit | !Parameter!!Description!!Unit | ||
|-valign="top" | |-valign="top" | ||
|width="20%"| | |width="20%"|Component status | ||
|width=" | |width="60%"| | ||
|width="20%"| | |width="20%"|Enabled/Disabled | ||
|- | |||
|Input directory | |||
| | |||
| - | |||
|- | |||
|Output directory | |||
| | |||
| - | |||
|- | |||
|Site prefix | |||
| file prefix for the study site | |||
| - | |||
|- | |||
|Case prefix | |||
| file prefix for the model scenario | |||
| - | |||
|- | |||
|Number of steps | |||
| | |||
| - | |||
|- | |||
|Number of soil layers | |||
| | |||
| - | |||
|- | |||
|Time step | |||
| time step for infiltration process | |||
| sec | |||
|- | |||
|} | |||
= Layer 1 = | |||
{|{{Prettytable}} class = "wikitable unsortable" cellspacing="0" cellpadding="0" style="margin:0em 0em 0em 0;" | |||
|- | |||
!Parameter!!Description!!Unit | |||
|-valign="top" | |||
|width="20%"|K_sat type | |||
|width="60%"| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
|width="20%"|- | |||
|- | |||
|K_sat | |||
| sat. hydraulic conductivity | |||
| m / s | |||
|- | |||
|K_init type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|K_init | |||
| init. hydraulic conductivity | |||
| m / s | |||
|- | |||
|theta_sat type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|theta_sat | |||
| sat. soil water content | |||
| - | |||
|- | |||
|theta_init type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|theta_init | |||
| init. soil water content | |||
| - | |||
|- | |||
|theta_r type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|theta_r | |||
| residual soil water content | |||
| - | |||
|- | |||
|psi_B type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|psi_B | |||
| bubbling pressure head | |||
| m | |||
|- | |||
|psi_A type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|psi_A | |||
| pressure head offset parameter | |||
| m | |||
|- | |||
|lambda type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|lambda | |||
| pore-size distribution parameter | |||
| - | |||
|- | |||
|c type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|c | |||
| trans. Brooks-Corey curvature | |||
| - | |||
|- | |||
|dz | |||
| vertical distance between nodes | |||
| m | |||
|- | |||
|nz | |||
| number of vertical nodes in layer | |||
| - | |||
|- | |||
|Closet soil_type | |||
| Closet standard soil_type | |||
| - | |||
|- | |||
|} | |||
= Layer 2 = | |||
{|{{Prettytable}} class = "wikitable unsortable" cellspacing="0" cellpadding="0" style="margin:0em 0em 0em 0;" | |||
|- | |||
!Parameter!!Description!!Unit | |||
|-valign="top" | |||
|width="20%"|K_sat type | |||
|width="60%"| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
|width="20%"|- | |||
|- | |||
|K_sat | |||
| sat. hydraulic conductivity | |||
| m / s | |||
|- | |||
|K_init type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|K_init | |||
| init. hydraulic conductivity | |||
| m / s | |||
|- | |||
|theta_sat type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|theta_sat | |||
| sat. soil water content | |||
| - | |||
|- | |||
|theta_init type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|theta_init | |||
| init. soil water content | |||
| - | |||
|- | |||
|theta_r type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|theta_r | |||
| residual soil water content | |||
| - | |||
|- | |||
|psi_B type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|psi_B | |||
| bubbling pressure head | |||
| m | |||
|- | |||
|psi_A type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|psi_A | |||
| pressure head offset parameter | |||
| m | |||
|- | |||
|lambda type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|lambda | |||
| pore-size distribution parameter | |||
| - | |||
|- | |||
|c type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|c | |||
| trans. Brooks-Corey curvature | |||
| - | |||
|- | |||
|dz | |||
| vertical distance between nodes | |||
| m | |||
|- | |||
|nz | |||
| number of vertical nodes in layer | |||
| - | |||
|- | |||
|Closet soil_type | |||
| Closet standard soil_type | |||
| - | |||
|- | |||
|} | |} | ||
= | |||
= Layer 3 = | |||
{|{{Prettytable}} class = "wikitable unsortable" cellspacing="0" cellpadding="0" style="margin:0em 0em 0em 0;" | {|{{Prettytable}} class = "wikitable unsortable" cellspacing="0" cellpadding="0" style="margin:0em 0em 0em 0;" | ||
|- | |- | ||
!Parameter!!Description!!Unit | !Parameter!!Description!!Unit | ||
|-valign="top" | |-valign="top" | ||
|width="20%"| | |width="20%"|K_sat type | ||
|width="60%"| | |width="60%"| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | ||
|width="20%"| | |width="20%"|- | ||
|- | |||
|K_sat | |||
| sat. hydraulic conductivity | |||
| m / s | |||
|- | |||
|K_init type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|K_init | |||
| init. hydraulic conductivity | |||
| m / s | |||
|- | |||
|theta_sat type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|theta_sat | |||
| sat. soil water content | |||
| - | |||
|- | |||
|theta_init type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|theta_init | |||
| init. soil water content | |||
| - | |||
|- | |||
|theta_r type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|theta_r | |||
| residual soil water content | |||
| - | |||
|- | |||
|psi_B type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|psi_B | |||
| bubbling pressure head | |||
| m | |||
|- | |||
|psi_A type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|psi_A | |||
| pressure head offset parameter | |||
| m | |||
|- | |||
|lambda type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|lambda | |||
| pore-size distribution parameter | |||
| - | |||
|- | |||
|c type | |||
| allowed input types (Scale/Grid/Time_series/Grid_Sequence) | |||
| - | |||
|- | |||
|c | |||
| trans. Brooks-Corey curvature | |||
| - | |||
|- | |||
|dz | |||
| vertical distance between nodes | |||
| m | |||
|- | |||
|nz | |||
| number of vertical nodes in layer | |||
| - | |||
|- | |||
|Closet soil_type | |||
| Closet standard soil_type | |||
| - | |||
|- | |||
|} | |} | ||
= | = Output 1 = | ||
{|{{Prettytable}} class = "wikitable unsortable" cellspacing="0" cellpadding="0" style="margin:0em 0em 0em 0;" | |||
|- | |||
!Parameter!!Description!!Unit | |||
|-valign="top" | |||
|width="20%"|Save grid timestep | |||
|width="60%"| time interval between saved grid | |||
|width="20%"|sec | |||
|- | |||
|Save v0 grids toggle | |||
| option to save grids of infil.rate (at surf) | |||
| - | |||
|- | |||
|Save v0 grids file | |||
| filename for grid stack of v0 | |||
| m / s | |||
|- | |||
|Save I grids toggle | |||
| option to save grids of cumul. infil.depth | |||
| - | |||
|- | |||
|Save I grids file | |||
| filename for grid stack of I | |||
| m | |||
|- | |||
|Save q0 grids toggle | |||
| option to save grids of soil water content (at surf) | |||
| - | |||
|- | |||
|Save q0 grids file | |||
| filename for grid stack of q0 | |||
| - | |||
|- | |||
|Save Zw grids toggle | |||
| option to save grids of depth to wetting front | |||
| - | |||
|- | |||
|Save Zw grids file | |||
| filename for grid stack of Zw | |||
| m | |||
|- | |||
|} | |||
= Output 2 = | |||
{|{{Prettytable}} class = "wikitable unsortable" cellspacing="0" cellpadding="0" style="margin:0em 0em 0em 0;" | |||
|- | |||
!Parameter!!Description!!Unit | |||
|-valign="top" | |||
|width="20%"|Save pixels timestep | |||
|width="60%"| time interval between time series value | |||
|width="20%"|sec | |||
|- | |||
|Save v0 pixels toggle | |||
| option to save time series of infil.rate (at surf) | |||
| - | |||
|- | |||
|Save v0 pixels file | |||
| filename for time series of v0 | |||
| m / s | |||
|- | |||
|Save I pixels toggle | |||
| option to save time series of cumul. infil.depth | |||
| - | |||
|- | |||
|Save I pixels file | |||
| filename for time series of I | |||
| m | |||
|- | |||
|Save q0 pixels toggle | |||
| option to save time series of soil water content (at surf) | |||
| - | |||
|- | |||
|Save q0 pixels file | |||
| filename for time series of q0 | |||
| - | |||
|- | |||
|Save Zw grids toggle | |||
| option to save grids of depth to wetting front | |||
| - | |||
|- | |||
|Save Zw grids file | |||
| filename for grid stack of Zw | |||
| m | |||
|- | |||
|} | |||
= Output 3 = | |||
{|{{Prettytable}} class = "wikitable unsortable" cellspacing="0" cellpadding="0" style="margin:0em 0em 0em 0;" | |||
|- | |||
!Parameter!!Description!!Unit | |||
|-valign="top" | |||
|width="20%"|Save profile timestep | |||
|width="60%"| time interval between 1D profiles | |||
|width="20%"|sec | |||
|- | |||
|Save q profiles toggle | |||
| option to 1D profile of soil water content | |||
| - | |||
|- | |||
|Save q profiles file | |||
| filename for 1D profile of theta | |||
| - | |||
|- | |||
|Save p profiles toggle | |||
| option to 1D profile of pressure head | |||
| - | |||
|- | |||
|Save p profiles file | |||
| filename for 1D profile of psi | |||
| m | |||
|- | |||
|Save K profiles toggle | |||
| option to save 1D profile of hydr. conductivity | |||
| - | |||
|- | |||
|Save K profiles file | |||
| filename for 1D profile of K | |||
| m / s | |||
|- | |||
|Save v profiles toggle | |||
| option to save 1D profile of vert. flow rate | |||
| - | |||
|- | |||
|Save v profiles file | |||
| filename for 1D profile of v | |||
| m / s | |||
|- | |||
|} | |||
<headertabs/> | <headertabs/> | ||
</div> | </div> | ||
==Uses ports== | ==Uses ports== | ||
< | |||
• Meteorology <br /> | |||
• Snow (Snowmelt) <br /> | |||
• Evap (Evaporation) <br /> | |||
• Satzone (Subsurface flow in saturated zone) <br /> | |||
• Channels (surface water flow in a network of channels) <br /> | |||
==Provides ports== | ==Provides ports== | ||
< | |||
• Infil (Infiltration) <br /> | |||
• Configure (tabbed dialog GUI to change settings) <br /> | |||
• Run (only if used as the Driver) <br /> | |||
==Main equations== | ==Main equations== | ||
* Darcy's law for vertical flow rate | * Darcy's law for vertical flow rate | ||
::::{| | ::::{| | ||
|width=500px|<math>v= K \left ( 1 - | |width=500px|<math>v= K \ast \left ( 1 - \Psi\right) </math> | ||
|width=50px align="right"|(1) | |width=50px align="right"|(1) | ||
|} | |} | ||
* Conservation of mass, with source/sink term J | * Conservation of mass, with source/sink term J (subscripts are partial derivatives) | ||
::::{| | ::::{| | ||
|width=500px|<math>v_{z}= J - theta_{t} </math> | |width=500px|<math>v_{z}= J - \theta_{t} </math> | ||
|width=50px align="right"|(2) | |width=50px align="right"|(2) | ||
|} | |} | ||
* Effective saturation or scaled water content, | * Effective saturation or scaled water content (in [0,1]. Equals 0 when θ = θ<sub>r</sub>. Equals 1 when θ = θ<sub>s</sub>.)) | ||
::::{| | ::::{| | ||
|width=500px|<math> | |width=500px|<math>\Theta_{e}= \left ( \theta - \theta_{r}\right) / \left ( \theta_{s} - \theta_{r} \right) </math> | ||
|width=50px align="right"|(3) | |width=50px align="right"|(3) | ||
|} | |} | ||
* Hydraulic conductivity | * Hydraulic conductivity | ||
::::{| | ::::{| | ||
|width=500px|<math>K= K_{s} | |width=500px|<math>K= K_{s} \ast \Theta_{e}^{\frac{\eta}{\lambda}} </math> | ||
|width=50px align="right"|(4) | |width=50px align="right"|(4) | ||
|} | |} | ||
* Pressure head | * Pressure head | ||
::::{| | ::::{| | ||
|width=500px|<math> | |width=500px|<math>\Psi= \Psi_{B} \left ( \Theta_{e}^{\frac{-c}{\lambda}} - 1 \right)^{\frac{1}{c}} - \Psi_{A} </math> | ||
|width=50px align="right"|(5) | |width=50px align="right"|(5) | ||
|} | |} | ||
<div class="NavFrame collapsed" style="text-align:left"> | <div class="NavFrame collapsed" style="text-align:left"> | ||
Line 118: | Line 543: | ||
|- | |- | ||
| η | | η | ||
| | | unit less, equals to 2 + ( 3*λ ) | ||
| | | | ||
|- | |- | ||
Line 131: | Line 556: | ||
| n<sub>nodes</sub> | | n<sub>nodes</sub> | ||
| number of subsurface vertical nodes | | number of subsurface vertical nodes | ||
| | | | ||
|- | |- | ||
Line 154: | Line 567: | ||
|- | |- | ||
| Θ<sub>e</sub> | | Θ<sub>e</sub> | ||
| effective saturation or scaled water content (unitless in [0,1]) | |||
| | | | ||
| | |- | ||
|} | |||
'''Output''' | |||
{| {{Prettytable}} class="wikitable sortable" | |||
!Symbol!!Description!!Unit | |||
|- | |||
| θ | |||
| soil moisture | |||
| none | |||
|- | |- | ||
| ψ | | ψ | ||
| pressure head | | pressure head | ||
| m | | m | ||
|- | |- | ||
| K | |||
| hydraulic conductivity | |||
| m / s | |||
|- | |||
| v | |||
| vertical flow rate | |||
| m / s | |||
|- | |||
|} | |} | ||
</div> | </div> | ||
</div> | </div> | ||
==Notes== | ==Notes== | ||
'''''Notes on Input Parameters''''' | |||
For each variable, you may choose from the droplist of data types. For the "Scalar" data type, enter a numeric value with the units indicated in the dialog. For the other data types, enter a filename. Values in files must also use the indicated units. | For each variable, you may choose from the droplist of data types. For the "Scalar" data type, enter a numeric value with the units indicated in the dialog. For the other data types, enter a filename. Values in files must also use the indicated units. | ||
Single grids and grid sequences are assumed to be stored as RTG and RTS files, respectively. Time series are assumed to be stored as text files, with one value per line. For a time series or grid sequence, the time between values must coincide with the timestep provided. | Single grids and grid sequences are assumed to be stored as RTG and RTS files, respectively. Time series are assumed to be stored as text files, with one value per line. For a time series or grid sequence, the time between values must coincide with the timestep provided. | ||
The current version allows up to 3 different soil layers, each with its own soil properties and number of vertical nodes. The soil layer number is indicated at the top of the dialog and you use the Next and Back buttons to view settings for the various layers. | |||
'''''Notes on the Equations''''' | |||
All variables and their units can be seen by expanding the Nomenclature section above. | |||
These equations are used to compute the time evolution of 1D (vertical, subsurface) profiles for (1) soil moisture, θ, (2) pressure head, ψ, (3) hydraulic conductivity, K and (4) vertical flow rate, v. TopoFlow solves these equations separately to get time-evolving profiles for every grid cell in a DEM. The result is a 3D grid for each of these four variables that spans the unsaturated zone. The third equation above just defines a variable that is used in the 4th and 5th equations, so the coupled set constitutes 4 equations to be solved for 4 unknowns. These equations can be combined into one nonlinear, parabolic, second-order PDE (partial differential equation) known as the one-dimensional Richards' equation. | These equations are used to compute the time evolution of 1D (vertical, subsurface) profiles for (1) soil moisture, θ, (2) pressure head, ψ, (3) hydraulic conductivity, K and (4) vertical flow rate, v. TopoFlow solves these equations separately to get time-evolving profiles for every grid cell in a DEM. The result is a 3D grid for each of these four variables that spans the unsaturated zone. The third equation above just defines a variable that is used in the 4th and 5th equations, so the coupled set constitutes 4 equations to be solved for 4 unknowns. These equations can be combined into one nonlinear, parabolic, second-order PDE (partial differential equation) known as the one-dimensional Richards' equation. | ||
The infiltration rate is simply the vertical flow rate at the ground surface, denoted by | The infiltration rate is simply the vertical flow rate at the ground surface, denoted by v<sub>0</sub>. | ||
Soil moisture is simply another term for the water content in the case where the porous medium is a soil. | Soil moisture is simply another term for the water content in the case where the porous medium is a soil. | ||
Line 195: | Line 619: | ||
Subscripts in the first two equations indicate partial derivatives with respect to the vertical coordinate, z. Note that z is the vertical distance below the ground surface, in meters. | Subscripts in the first two equations indicate partial derivatives with respect to the vertical coordinate, z. Note that z is the vertical distance below the ground surface, in meters. | ||
More information on how soil is modeled in TopoFlow along with published soil property tables can be found on this soil properties page . | More information on how soil is modeled in TopoFlow along with published soil property tables can be found on this | ||
[[Model help:TopoFlow-Soil Properties Page|soil properties page]]. | |||
Two other, simpler methods for modeling infiltration are described on the help pages for the Green-Ampt method and the Smith-Parlange 3-parameter method. | Two other, simpler methods for modeling infiltration are described on the help pages for the [https://csdms.colorado.edu/wiki/Model_help:TopoFlow-Infiltration-Green-Ampt Green-Ampt method] and the [https://csdms.colorado.edu/wiki/Model_help:TopoFlow-Infiltration-Smith-Parlange Smith-Parlange 3-parameter method]. | ||
==Examples== | ==Examples== | ||
Line 203: | Line 628: | ||
<span class="remove_this_tag">Follow the next steps to include images / movies of simulations:</span> | <span class="remove_this_tag">Follow the next steps to include images / movies of simulations:</span> | ||
* <span class="remove_this_tag">Upload file: | * <span class="remove_this_tag">Upload file: https://csdms.colorado.edu/wiki/Special:Upload</span> | ||
* <span class="remove_this_tag">Create link to the file on your page: <nowiki>[[Image:<file name>]]</nowiki>.</span> | * <span class="remove_this_tag">Create link to the file on your page: <nowiki>[[Image:<file name>]]</nowiki>.</span> | ||
Line 209: | Line 634: | ||
==Developer(s)== | ==Developer(s)== | ||
[[User: | [[User:Peckhams|Scott Peckham]] | ||
==References== | ==References== | ||
Line 217: | Line 642: | ||
==Links== | ==Links== | ||
* [[ | |||
* [[ | '''''Related Help Pages''''' | ||
* [[Model help:TopoFlow-Infiltration-Green-Ampt]] | |||
* [[Model help:TopoFlow-Infiltration-Smith-Parlange]] | |||
* [[Model help:TopoFlow-Saturated_Zone-Darcy_Layers]] | |||
* [[Model help:TopoFlow-Soil Properties Page]] | |||
'''''Model Metadata''''' | |||
* [[Model:TopoFlow-Infiltration-Richards_1D]] | |||
* [[Model:TopoFlow]] | |||
[[Category:Modules]] | [[Category:Modules]] |
Latest revision as of 17:19, 19 February 2018
TopoFlow-Infiltration-Richards 1D
This module is the infiltration process component (Richards 1D method) for a D8-based, spatial hydrologic model.
Model introduction
This process component is part of a spatially-distributed hydrologic model called TopoFlow, but it can now be used as a stand-alone model.
Model parameters
Uses ports
• Meteorology
• Snow (Snowmelt)
• Evap (Evaporation)
• Satzone (Subsurface flow in saturated zone)
• Channels (surface water flow in a network of channels)
Provides ports
• Infil (Infiltration)
• Configure (tabbed dialog GUI to change settings)
• Run (only if used as the Driver)
Main equations
- Darcy's law for vertical flow rate
[math]\displaystyle{ v= K \ast \left ( 1 - \Psi\right) }[/math] (1)
- Conservation of mass, with source/sink term J (subscripts are partial derivatives)
[math]\displaystyle{ v_{z}= J - \theta_{t} }[/math] (2)
- Effective saturation or scaled water content (in [0,1]. Equals 0 when θ = θr. Equals 1 when θ = θs.))
[math]\displaystyle{ \Theta_{e}= \left ( \theta - \theta_{r}\right) / \left ( \theta_{s} - \theta_{r} \right) }[/math] (3)
- Hydraulic conductivity
[math]\displaystyle{ K= K_{s} \ast \Theta_{e}^{\frac{\eta}{\lambda}} }[/math] (4)
- Pressure head
[math]\displaystyle{ \Psi= \Psi_{B} \left ( \Theta_{e}^{\frac{-c}{\lambda}} - 1 \right)^{\frac{1}{c}} - \Psi_{A} }[/math] (5)
Symbol | Description | Unit |
---|---|---|
Ks | saturated hydraulic conductivity | [m / s] |
Ki | initial hydraulic conductivity (typically much less than Ks) | [m / s] |
θs | soil water content at ψ = 0 (often set to the soil porosity, φ) | [-] |
θi | initial soil water content | [-] |
θr | residual soil water content (must be < θi) | [-] |
ψB | bubbling pressure head (also called air-entry pressure, ψae) | m |
ψA | pressure head offset parameter | m |
λ | pore-size distribution parameter (alt. notation - 1/b) | - |
η | unit less, equals to 2 + ( 3*λ ) | |
c | transitional Brooks-Corey curvature parameter | |
dznodes | vertical distance between nodes | m |
nnodes | number of subsurface vertical nodes | |
J | source / sink | |
θt | - | |
Θe | effective saturation or scaled water content (unitless in [0,1]) |
Output
Symbol | Description | Unit |
---|---|---|
θ | soil moisture | none |
ψ | pressure head | m |
K | hydraulic conductivity | m / s |
v | vertical flow rate | m / s |
Notes
Notes on Input Parameters
For each variable, you may choose from the droplist of data types. For the "Scalar" data type, enter a numeric value with the units indicated in the dialog. For the other data types, enter a filename. Values in files must also use the indicated units.
Single grids and grid sequences are assumed to be stored as RTG and RTS files, respectively. Time series are assumed to be stored as text files, with one value per line. For a time series or grid sequence, the time between values must coincide with the timestep provided.
The current version allows up to 3 different soil layers, each with its own soil properties and number of vertical nodes. The soil layer number is indicated at the top of the dialog and you use the Next and Back buttons to view settings for the various layers.
Notes on the Equations
All variables and their units can be seen by expanding the Nomenclature section above.
These equations are used to compute the time evolution of 1D (vertical, subsurface) profiles for (1) soil moisture, θ, (2) pressure head, ψ, (3) hydraulic conductivity, K and (4) vertical flow rate, v. TopoFlow solves these equations separately to get time-evolving profiles for every grid cell in a DEM. The result is a 3D grid for each of these four variables that spans the unsaturated zone. The third equation above just defines a variable that is used in the 4th and 5th equations, so the coupled set constitutes 4 equations to be solved for 4 unknowns. These equations can be combined into one nonlinear, parabolic, second-order PDE (partial differential equation) known as the one-dimensional Richards' equation.
The infiltration rate is simply the vertical flow rate at the ground surface, denoted by v0.
Soil moisture is simply another term for the water content in the case where the porous medium is a soil.
Subscripts in the first two equations indicate partial derivatives with respect to the vertical coordinate, z. Note that z is the vertical distance below the ground surface, in meters.
More information on how soil is modeled in TopoFlow along with published soil property tables can be found on this soil properties page.
Two other, simpler methods for modeling infiltration are described on the help pages for the Green-Ampt method and the Smith-Parlange 3-parameter method.
Examples
An example run with input parameters, BLD files, as well as a figure / movie of the output
Follow the next steps to include images / movies of simulations:
- Upload file: https://csdms.colorado.edu/wiki/Special:Upload
- Create link to the file on your page: [[Image:<file name>]].
See also: Help:Images or Help:Movies
Developer(s)
References
Dingman, S.L. (2002) Physical Hydrology, 2nd ed., Prentice-Hall, Upper Saddle River, New Jersey, 646 pp.
Smith, R.E. (2002) Infiltration Theory for Hydrologic Applications, Water Resources Monograph 15, AGU, 212 pp.
Links
Related Help Pages
- Model help:TopoFlow-Infiltration-Green-Ampt
- Model help:TopoFlow-Infiltration-Smith-Parlange
- Model help:TopoFlow-Saturated_Zone-Darcy_Layers
- Model help:TopoFlow-Soil Properties Page
Model Metadata