MODFLOW 6: Accessing Simulation Settings, Models, and Packages
This tutorial shows how to view, access, and change the underlying package variables for MODFLOW 6 objects in FloPy. Interaction with a FloPy MODFLOW 6 model is different from other models, such as MODFLOW-2005, MT3D, and SEAWAT, for example.
The MODFLOW 6 simulation structure is arranged in the following generalized way:
SIMULATION --> PACKAGE --> Data SIMULATION --> MODEL --> PACKAGE (--> PACKAGE) --> Data
This tutorial focuses on accessing simulation-wide FloPy settings and how to create and access models and packages. Tutorial 3, 4, and 5 offer a more in depth look at observation, time series, and time array series packages, and tutorial 6, 7, 8, and 9 offer a more in depth look at the data.
Create Simple Demonstration Model
This tutorial uses a simple demonstration simulation with one GWF Model. The model has 3 layers, 4 rows, and 5 columns. The model is set up to use multiple model layers in order to demonstrate some of the layered functionality in FloPy.
[1]:
# package import
from tempfile import TemporaryDirectory
[2]:
import flopy
[3]:
temp_dir = TemporaryDirectory()
workspace = temp_dir.name
name = "tutorial01_mf6_data"
[4]:
# set up simulation and basic packages
sim = flopy.mf6.MFSimulation(sim_name=name, sim_ws=workspace)
flopy.mf6.ModflowTdis(
sim, nper=10, perioddata=[[365.0, 1, 1.0] for _ in range(10)]
)
flopy.mf6.ModflowIms(sim)
gwf = flopy.mf6.ModflowGwf(sim, modelname=name, save_flows=True)
flopy.mf6.ModflowGwfdis(gwf, nlay=3, nrow=4, ncol=5)
flopy.mf6.ModflowGwfic(gwf)
flopy.mf6.ModflowGwfnpf(gwf, save_specific_discharge=True)
flopy.mf6.ModflowGwfchd(
gwf, stress_period_data=[[(0, 0, 0), 1.0], [(2, 3, 4), 0.0]]
)
budget_file = f"{name}.bud"
head_file = f"{name}.hds"
flopy.mf6.ModflowGwfoc(
gwf,
budget_filerecord=budget_file,
head_filerecord=head_file,
saverecord=[("HEAD", "ALL"), ("BUDGET", "ALL")],
)
print("Done creating simulation.")
Done creating simulation.
Accessing Simulation-Level Settings
FloPy has a number of settings that can be set for the entire simulation. These include how much information FloPy writes to the console, how to format the MODFLOW package files, and whether to verify MODFLOW data.
The verbosity level, which determines how much FloPy writes to command line output. The options are 1 for quiet, 2 for normal, and 3 for verbose. Below we set the verbosity level to verbose.
[5]:
sim.simulation_data.verbosity_level = 3
We can also set the number of spaces to indent data when writing package files by setting the indent string.
[6]:
sim.simulation_data.indent_string = " "
Next we set the precision and number of characters written for floating point variables.
[7]:
sim.float_precision = 8
sim.float_characters = 15
Lastly, we disable verify_data and auto_set_sizes for faster performance. With these options disabled FloPy will not do any checking or autocorrecting of your data.
[8]:
sim.verify_data = False
sim.auto_set_sizes = False
Accessing Models and Packages
At this point a simulation is available in memory. In this particular case the simulation was created directly using Python code; however, the simulation might also have been loaded from existing model files using the FloPy.mf6.MFSimulation.load() function.
Once a MODFLOW 6 simulation is available in memory, the contents of the simulation object can be listed using a simple print command.
[9]:
print(sim)
sim_name = tutorial01_mf6_data
sim_path = /tmp/tmp6wt3tmrp
exe_name = mf6
###################
Package mfsim.nam
###################
package_name = mfsim.nam
filename = mfsim.nam
package_type = nam
model_or_simulation_package = simulation
simulation_name = tutorial01_mf6_data
###################
Package tutorial01_mf6_data.tdis
###################
package_name = tutorial01_mf6_data.tdis
filename = tutorial01_mf6_data.tdis
package_type = tdis
model_or_simulation_package = simulation
simulation_name = tutorial01_mf6_data
###################
Package ims_-1
###################
package_name = ims_-1
filename = tutorial01_mf6_data.ims
package_type = ims
model_or_simulation_package = simulation
simulation_name = tutorial01_mf6_data
@@@@@@@@@@@@@@@@@@@@
Model tutorial01_mf6_data
@@@@@@@@@@@@@@@@@@@@
name = tutorial01_mf6_data
model_type = gwf6
version = mf6
model_relative_path = .
###################
Package dis
###################
package_name = dis
filename = tutorial01_mf6_data.dis
package_type = dis
model_or_simulation_package = model
model_name = tutorial01_mf6_data
###################
Package ic
###################
package_name = ic
filename = tutorial01_mf6_data.ic
package_type = ic
model_or_simulation_package = model
model_name = tutorial01_mf6_data
###################
Package npf
###################
package_name = npf
filename = tutorial01_mf6_data.npf
package_type = npf
model_or_simulation_package = model
model_name = tutorial01_mf6_data
###################
Package chd_0
###################
package_name = chd_0
filename = tutorial01_mf6_data.chd
package_type = chd
model_or_simulation_package = model
model_name = tutorial01_mf6_data
###################
Package oc
###################
package_name = oc
filename = tutorial01_mf6_data.oc
package_type = oc
model_or_simulation_package = model
model_name = tutorial01_mf6_data
Simulation-level packages, models, and model packages can be shown by printing the simulation object. In this case, you should see the all of the contents of simulation and some information about each FloPy object that is part of simulation.
To get the TDIS package and print the contents, we can do the following
[10]:
tdis = sim.tdis
print(tdis)
package_name = tutorial01_mf6_data.tdis
filename = tutorial01_mf6_data.tdis
package_type = tdis
model_or_simulation_package = simulation
simulation_name = tutorial01_mf6_data
Block dimensions
--------------------
nper
{internal}
(10)
Block perioddata
--------------------
perioddata
{internal}
([(365., 1, 1.) (365., 1, 1.) (365., 1, 1.) (365., 1, 1.) (365., 1, 1.)
(365., 1, 1.) (365., 1, 1.) (365., 1, 1.) (365., 1, 1.) (365., 1, 1.)])
To get the Iterative Model Solution (IMS) object, we use the following syntax
[11]:
ims = sim.get_package("ims_-1")
print(ims)
package_name = ims_-1
filename = tutorial01_mf6_data.ims
package_type = ims
model_or_simulation_package = simulation
simulation_name = tutorial01_mf6_data
Or because there is only one IMS object for this simulation, we can access it as
[12]:
ims = sim.get_package("ims")
print(ims)
package_name = ims_-1
filename = tutorial01_mf6_data.ims
package_type = ims
model_or_simulation_package = simulation
simulation_name = tutorial01_mf6_data
When printing the sim object, there is also a simulation package called nam. This package contains the information that is written to the mfsim.nam file, which is the primary file that MODFLOW 6 reads when it first starts. The nam package is automatically updated for you by FloPy and does not require modification.
[13]:
nam = sim.get_package("nam")
print(nam)
package_name = mfsim.nam
filename = mfsim.nam
package_type = nam
model_or_simulation_package = simulation
simulation_name = tutorial01_mf6_data
Block timing
--------------------
tdis6
{internal}
(tutorial01_mf6_data.tdis)
Block models
--------------------
models
{internal}
([('gwf6', 'tutorial01_mf6_data.nam', 'tutorial01_mf6_data')])
Block solutiongroup
--------------------
solutiongroup
{internal}
([('ims6', 'tutorial01_mf6_data.ims', 'tutorial01_mf6_data')])
To see the models that are contained within the simulation, we can get a list of their names as follows
[14]:
print(sim.model_names)
['tutorial01_mf6_data']
sim.model_names returns the keys of an ordered dictionary, which isn’t very useful to us, but we can convert that to a list and then go through that list and print information about each model in the simulation. In this case there is only one model, but had there been more models, we would see them listed here
[15]:
model_names = list(sim.model_names)
for mname in model_names:
print(mname)
tutorial01_mf6_data
If we want to get a model from a simulation, then we use the get_model() method of the sim object. Here we go through all the models in the simulation and print the model name and the model type.
[16]:
model_names = list(sim.model_names)
for mname in model_names:
m = sim.get_model(mname)
print(m.name, m.model_type)
tutorial01_mf6_data gwf6
For this simple case here with only one GWF model, we can very easily get the FloPy representation of the GWF model as
[17]:
gwf = sim.get_model(name)
Now that we have the GWF object, we can print it, and see what’s it contains.
[18]:
print(gwf)
name = tutorial01_mf6_data
model_type = gwf6
version = mf6
model_relative_path = .
###################
Package dis
###################
package_name = dis
filename = tutorial01_mf6_data.dis
package_type = dis
model_or_simulation_package = model
model_name = tutorial01_mf6_data
###################
Package ic
###################
package_name = ic
filename = tutorial01_mf6_data.ic
package_type = ic
model_or_simulation_package = model
model_name = tutorial01_mf6_data
###################
Package npf
###################
package_name = npf
filename = tutorial01_mf6_data.npf
package_type = npf
model_or_simulation_package = model
model_name = tutorial01_mf6_data
###################
Package chd_0
###################
package_name = chd_0
filename = tutorial01_mf6_data.chd
package_type = chd
model_or_simulation_package = model
model_name = tutorial01_mf6_data
###################
Package oc
###################
package_name = oc
filename = tutorial01_mf6_data.oc
package_type = oc
model_or_simulation_package = model
model_name = tutorial01_mf6_data
What we see here is the information that we saw when we printed the sim object.
One of the most common operations on a model is to see what packages are in it and then get packages of interest. A list of packages in a model can obtained as
[19]:
package_list = gwf.get_package_list()
print(package_list)
['DIS', 'IC', 'NPF', 'CHD_0', 'OC']
As you might expect we can access each package in this list with gwf.get_package(). Thus, the following syntax can be used to obtain and print the contents of the DIS Package
[20]:
dis = gwf.get_package("dis")
print(dis)
package_name = dis
filename = tutorial01_mf6_data.dis
package_type = dis
model_or_simulation_package = model
model_name = tutorial01_mf6_data
Block dimensions
--------------------
nlay
{internal}
(3)
nrow
{internal}
(4)
ncol
{internal}
(5)
Block griddata
--------------------
delr
{constant 1.0}
delc
{constant 1.0}
top
{constant 1.0}
botm
{constant 0.0}
The Python type for this dis package is simply
[21]:
print(type(dis))
<class 'flopy.mf6.modflow.mfgwfdis.ModflowGwfdis'>
[22]:
try:
temp_dir.cleanup()
except PermissionError:
# can occur on windows: https://docs.python.org/3/library/tempfile.html#tempfile.TemporaryDirectory
pass