# Groundwater flow

## Confined aquifer

The Table below shows the parameters (fields) of struct ConfinedAquifer, including a description of these parameters, the unit, and default value if applicable. Struct ConfinedAquifer is not (yet) part of a Wflow Model.

parameterdescriptionunitdefault
khorizontal conductivitym d$^{-1}$s-
storativitystorativitym m$^{-1}$-
specific_storagespecific storagem$^{-1}$- }
toptop groundwater layersm-
bottombottom groundwater layersm-
areacell aream$^2$-
headgroundwater headm-
conductanceconductancem$^2$ d$^{-1}$-

## Unconfined aquifer

The Table below shows the parameters (fields) of struct UnconfinedAquifer, including a description of these parameters, the unit, and default value if applicable. The parameters in bold represent model parameters that can be set through static input data (netCDF), and can be listed in the TOML configuration file under [lateral.subsurface], to map the internal model parameter to the external netCDF variable. For some input parameters the parameter listed under [lateral.subsurface] is not equal to the internal model parameter, these are listed in the Table below between parentheses after the internal model parameter. The top parameter is provided by the exteral parameter altitude as part of the static input data and set as follows through the TOML file:

[input]
# these are not directly part of the model
altitude = "wflow_dem"
parameterdescriptionunitdefault
k (conductivity)horizontal conductivitym d$^{-1}$s-
specific_yieldspecific yieldm m$^{-1}$-
top (altitude)top groundwater layerm-
bottombottom groundwater layerm-
areacell aream$^2$-
headgroundwater headm-
conductanceconductancem$^2$ d$^{-1}$-

## Constant Head

The Table below shows the parameters (fields) of struct ConstantHead, including a description of these parameters, the unit, and default value if applicable. The parameters in bold represent model parameters that can be set through static input data (netCDF), and can be listed in the TOML configuration file under [lateral.subsurface], to map the internal model parameter to the external netCDF variable. For some input parameters the parameter listed under [lateral.subsurface] is not equal to the internal model parameter, these are listed in the Table below between parentheses after the internal model parameter.

parameterdescriptionunitdefault
head (constant_head)groundwater headm-
indexconstand head cell index--

## Boundary conditions

### River

The Table below shows the parameters (fields) of struct River, including a description of these parameters, the unit, and default value if applicable. The parameters in bold represent model parameters that can be set through static input data (netCDF), and can be listed in the TOML configuration file under [lateral.subsurface], to map the internal model parameter to the external netCDF variable. For some input parameters the parameter listed under [lateral.subsurface] is not equal to the internal model parameter, these are listed in the Table below between parentheses after the internal model parameter.

parameterdescriptionunitdefault
stageriver stagem-
infiltration_conductanceriver bed infiltration conductancem$^2$ day$^{-1}$ m$^2$ day$^{-1}$-
exfiltration_conductanceriver bed exfiltration conductancem$^2$ day$^{-1}$-
bottom (river_bottom)river bottom elevationm-
indexriver cell index--
fluxexchange flux (river to aquifer)m$^3$ d$^{-1}$-

### Drainage

The Table below shows the parameters (fields) of struct Drainage, including a description of these parameters, the unit, and default value if applicable. The parameters in bold represent model parameters that can be set through static input data (netCDF), and can be listed in the TOML configuration file under [lateral.subsurface], to map the internal model parameter to the external netCDF variable. For some input parameters the parameter listed under [lateral.subsurface] is not equal to the internal model parameter, these are listed in the Table below between parentheses after the internal model parameter.

parameterdescriptionunitdefault
elevation (drain_elevation)drain elevationm-
conductance (drain_conductance)drain conductancem$^2$ day$^{-1}$-
index (drain)drain cell index--
fluxexchange flux (drains to aquifer)m$^3$ day$^{-1}$-

### Recharge

The Table below shows the parameters (fields) of struct Recharge, including a description of these parameters, the unit, and default value if applicable.

parameterdescriptionunitdefault
raterecharge ratem$^3$ day$^{-1}$-
indexrecharge cell index--
fluxrecharge fluxm$^3$ day$^{-1}$-

### Head boundary

The Table below shows the parameters (fields) of struct HeadBoundary, including a description of these parameters, the unit, and default value if applicable.

parameterdescriptionunitdefault
headheadm-
conductanceconductance of the head boundarym$^2$ day$^{-1}$-
indexhead boundary cell index--
fluxconductance of the head boundarym$^3$ day$^{-1}$-

### Well boundary

The Table below shows the parameters (fields) of struct Well, including a description of these parameters, the unit, and default value if applicable.

input parameterdescriptionunitdefault
volumetric_ratevolumetric well ratem$^3$ d$^{-1}$-
indexwell index--
fluxactual well fluxm$^3$ day$^{-1}$-