# Source code for imod.mf6.npf

```
import numpy as np
from imod.mf6.pkgbase import Package
[docs]class NodePropertyFlow(Package):
"""
Node Property Flow package.
In this package the hydraulic conductivity and rewetting in the model is
specified. A single NPF Package is required for each GWF model.
https://water.usgs.gov/water-resources/software/MODFLOW-6/mf6io_6.0.4.pdf#page=51
Parameters
----------
icelltype: array of int (xr.DataArray)
flag for each cell that specifies how saturated thickness is treated. 0
means saturated thickness is held constant; >0 means saturated thickness
varies with computed head when head is below the cell top; <0 means
saturated thickness varies with computed head unless the
starting_head_as_confined_thickness option is in effect. When
starting_head_as_confined_thickness is in effect, a negative value of
icelltype indicates that saturated thickness will be computed as
strt-bot and held constant.
k: array of floats (xr.DataArray)
is the hydraulic conductivity. For the common case in which the user
would like to specify the horizontal hydraulic conductivity and the
vertical hydraulic conductivity, then K should be assigned as the
horizontal hydraulic conductivity, K33 should be assigned as the
vertical hydraulic conductivity, and K22 and the three rotation
angles should not be specified. When more sophisticated anisotropy is
required, then K corresponds to the K11 hydraulic conductivity axis. All
included cells (idomain > 0) must have a K value greater than zero
rewet: ({True, False}, optional)
activates model rewetting.
Default is False.
rewet_layer: float
is a combination of the wetting threshold and a flag to indicate which
neighboring cells can cause a cell to become wet. If rewet_layer < 0,
only a cell below a dry cell can cause the cell to become wet. If
rewet_layer > 0, the cell below a dry cell and horizontally adjacent
cells can cause a cell to become wet. If rewet_layer is 0, the cell
cannot be wetted. The absolute value of rewet_layer is the wetting
threshold. When the sum of BOT and the absolute value of rewet_layer at
a dry cell is equaled or exceeded by the head at an adjacent cell, the
cell is wetted. rewet_layer must be specified if “rewet” is specified in
the OPTIONS block. If “rewet” is not specified in the options block,
then rewet_layer can be entered, and memory will be allocated for it,
even though it is not used. (WETDRY)
Default is None.
rewet_factor:
is a keyword and factor that is included in the calculation of the head
that is initially established at a cell when that cell is converted from
dry to wet. (WETFCT)
Default is None.
rewet_iterations:
is a keyword and iteration interval for attempting to wet cells. Wetting
is attempted every rewet_iterations iteration. This applies to outer
iterations and not inner iterations. If rewet_iterations is specified as
zero or less, then the value is changed to 1. (IWETIT)
Default is None.
rewet_method:
is a keyword and integer flag that determines which equation is used to
define the initial head at cells that become wet. If rewet_method is 0,
h = BOT + rewet_factor (hm - BOT). If rewet_method is not 0, h = BOT +
rewet_factor (THRESH). (IHDWET)
Default is None.
k22: array of floats (xr.DataArray)
is the hydraulic conductivity of the second ellipsoid axis; for an
unrotated case this is the hydraulic conductivity in the y direction. If
K22 is not included, then K22 is set equal to K.
For a regular MODFLOW grid (DIS Package is used) in which no rotation
angles are specified, K22 is the hydraulic conductivity along columns in
the y direction. For an unstructured DISU grid, the user must assign
principal x and y axes and provide the angle for each cell face relative
to the assigned x direction. All included cells (idomain > 0) must have
a K22 value greater than zero.
Default is None.
k33: array of floats (xr.DataArray)
is the hydraulic conductivity of the third ellipsoid axis; for an
unrotated case, this is the vertical hydraulic conductivity. When
anisotropy is applied, K33 corresponds to the K33 tensor component. All
included cells (idomain > 0) must have a K33 value greater than zero.
Default is None.
angle1: float
is a rotation angle of the hydraulic conductivity tensor in degrees. The
angle represents the first of three sequential rotations of the
hydraulic conductivity ellipsoid. With the K11, K22, and K33 axes of the
ellipsoid initially aligned with the x, y, and z coordinate axes,
respectively, angle1 rotates the ellipsoid about its K33 axis (within
the x - y plane). A positive value represents counter-clockwise rotation
when viewed from any point on the positive K33 axis, looking toward the
center of the ellipsoid. A value of zero indicates that the K11 axis
lies within the x - z plane. If angle1 is not specified, default values
of zero are assigned to angle1, angle2, and angle3, in which case the
K11, K22, and K33 axes are aligned with the x, y, and z axes,
respectively.
Default is None.
angle2: float
is a rotation angle of the hydraulic conductivity tensor in degrees. The
angle represents the second of three sequential rotations of the
hydraulic conductivity ellipsoid. Following the rotation by angle1
described above, angle2 rotates the ellipsoid about its K22 axis (out of
the x - y plane). An array can be specified for angle2 only if angle1 is
also specified. A positive value of angle2 represents clockwise rotation
when viewed from any point on the positive K22 axis, looking toward the
center of the ellipsoid. A value of zero indicates that the K11 axis
lies within the x - y plane. If angle2 is not specified, default values
of zero are assigned to angle2 and angle3; connections that are not
user-designated as vertical are assumed to be strictly horizontal (that
is, to have no z component to their orientation); and connection lengths
are based on horizontal distances.
Default is None.
angle3: float
is a rotation angle of the hydraulic conductivity tensor in degrees. The
angle represents the third of three sequential rotations of the
hydraulic conductivity ellipsoid. Following the rotations by angle1 and
angle2 described above, angle3 rotates the ellipsoid about its K11 axis.
An array can be specified for angle3 only if angle1 and angle2 are also
specified. An array must be specified for angle3 if angle2 is specified.
A positive value of angle3 represents clockwise rotation when viewed
from any point on the positive K11 axis, looking toward the center of
the ellipsoid. A value of zero indicates that the K22 axis lies within
the x - y plane.
Default is None.
cell_averaging : str
Method calculating horizontal cell connection conductance.
Options: {"harmonic", "logarithmic", "mean-log_k", "mean-mean_k"}
Default: "harmonic"
save_flows: ({True, False}, optional)
keyword to indicate that cell-by-cell flow terms will be written to the
file specified with “budget save file” in Output Control.
Default is False.
starting_head_as_confined_thickness: ({True, False}, optional)
indicates that cells having a negative icelltype are confined, and their
cell thickness for conductance calculations will be computed as strt-bot
rather than top-bot.
(THICKSTRT)
Default is False.
variable_vertical_conductance: ({True, False}, optional)
keyword to indicate that the vertical conductance will be calculated
using the saturated thickness and properties of the overlying cell and
the thickness and properties of the underlying cell. if the dewatered
keyword is also specified, then the vertical conductance is calculated
using only the saturated thickness and properties of the overlying cell
if the head in the underlying cell is below its top. if these keywords
are not specified, then the default condition is to calculate the
vertical conductance at the start of the simulation using the initial
head and the cell properties. the vertical conductance remains constant
for the entire simulation.
(VARIABLECV)
Default is False.
dewatered: ({True, False}, optional)
If the dewatered keyword is specified, then the vertical conductance is
calculated using only the saturated thickness and properties of the
overlying cell if the head in the underlying cell is below its top.
Default is False.
perched: ({True, False}, optional)
keyword to indicate that when a cell is overlying a dewatered
convertible cell, the head difference used in Darcy’s Law is equal to
the head in the overlying cell minus the bottom elevation of the
overlying cell. If not specified, then the default is to use the head
difference between the two cells.
Default is False.
save_specific_discharge: ({True, False}, optional)
keyword to indicate that x, y, and z components of specific discharge
will be calculated at cell centers and written to the cell-by-cell flow
file, which is specified with“budget save file” in Output Control. If
this option is activated, then additional information may be required in
the discretization packages and the GWF Exchange package (if GWF models
are coupled). Specifically, angldegx must be specified in the
connectiondata block of the disu package; angldegx must also be
specified for the GWF Exchange as an auxiliary variable. disu package
has not been implemented yet.
Default is False.
"""
__slots__ = (
"icelltype",
"k",
"rewet",
"rewet_layer",
"rewet_factor",
"rewet_iterations",
"rewet_method",
"k22",
"k33",
"angle1",
"angle2",
"angle3",
"cell_averaging",
"save_flows",
"starting_head_as_confined_thickness",
"variable_vertical_conductance",
"dewatered",
"perched",
"save_specific_discharge",
)
_pkg_id = "npf"
_grid_data = {
"icelltype": np.int32,
"k": np.float64,
"rewet_layer": np.float64,
"k22": np.float64,
"k33": np.float64,
"angle1": np.float64,
"angle2": np.float64,
"angle3": np.float64,
}
_keyword_map = {
"rewet": "rewet_record",
"rewet_factor": "wetfct",
"rewet_method": "ihdwet",
"rewet_layer": "wetdry",
"variable_vertical_conductance": "variablecv",
"starting_head_as_confined_thickness": "thickstrt",
"rewet_iterations": "iwetit",
}
_template = Package._initialize_template(_pkg_id)
def __init__(
self,
icelltype,
k,
rewet=False,
rewet_layer=None,
rewet_factor=None,
rewet_iterations=None,
rewet_method=None,
k22=None,
k33=None,
angle1=None,
angle2=None,
angle3=None,
cell_averaging="harmonic",
save_flows=False,
starting_head_as_confined_thickness=False,
variable_vertical_conductance=False,
dewatered=False,
perched=False,
save_specific_discharge=False,
):
super(__class__, self).__init__()
# check rewetting
if not rewet and any(
[rewet_layer, rewet_factor, rewet_iterations, rewet_method]
):
raise ValueError(
"rewet_layer, rewet_factor, rewet_iterations, and rewet_method should"
" all be left at a default value of None if rewet is False."
)
self["icelltype"] = icelltype
self["k"] = k
self["rewet"] = rewet
self["rewet_layer"] = rewet_layer
self["rewet_factor"] = rewet_factor
self["rewet_iterations"] = rewet_iterations
self["rewet_method"] = rewet_method
self["k22"] = k22
self["k33"] = k33
self["angle1"] = angle1
self["angle2"] = angle2
self["angle3"] = angle3
self["cell_averaging"] = cell_averaging
self["save_flows"] = save_flows
self[
"starting_head_as_confined_thickness"
] = starting_head_as_confined_thickness
self["variable_vertical_conductance"] = variable_vertical_conductance
self["dewatered"] = dewatered
self["perched"] = perched
self["save_specific_discharge"] = save_specific_discharge
[docs] def render(self, directory, pkgname, *args, **kwargs):
d = {}
npfdirectory = directory / "npf"
for varname in self.data_vars:
key = self._keyword_map.get(varname, varname)
if varname in self._grid_data:
layered, value = self._compose_values(self[varname], npfdirectory, key)
if self._valid(value): # skip False or None
d[f"{key}_layered"], d[key] = layered, value
else:
value = self[varname].values[()]
if self._valid(value): # skip False or None
d[key] = value
return self._template.render(d)
```