MODFLOW 6: Data Storage Information - How and Where to Store MODFLOW-6 Data¶
This tutorial shows the different options for storing MODFLOW data in FloPy. Interaction with a FloPy MODFLOW 6 model is different from other models, such as MODFLOW-2005, MT3D, and SEAWAT, for example.
FloPy stores model data in data objects (MFDataArray, MFDataList, MFDataScalar objects) that are accessible from packages. Data can be added to a package by using the appropriate parameters when the package is constructed and through package attributes.
The MODFLOW 6 simulation structure is arranged in the following generalized way:
Simulation --> Package --> DATA Simulation --> Model --> Package (--> Package) --> DATA
This tutorial focuses on the different storage options for MODFLOW data.
Introduction to Data Storage Information¶
MODFLOW array and list data can either be stored internally or externally in text or binary files. Additionally array data can have a factor applied to them and can have a format flag/code to define how these data will be formatted. This data storage information is specified within a python dictionary. The python dictionary must contain a “data” key where the data is stored and supports several other keys that determine how and where the data is stored.
The following code sets up a basic simulation with a groundwater flow model. for the example below.
[1]:
# package import
import os
[2]:
import numpy as np
[3]:
import flopy
[4]:
# set up where simulation workspace will be stored
workspace = os.path.join("data", "mf6_working_with_data")
name = "example_1"
if not os.path.exists(workspace):
os.makedirs(workspace)
# create the FloPy simulation and tdis objects
sim = flopy.mf6.MFSimulation(
sim_name=name, exe_name="mf6", version="mf6", sim_ws=workspace
)
tdis = flopy.mf6.modflow.mftdis.ModflowTdis(
sim,
pname="tdis",
time_units="DAYS",
nper=2,
perioddata=[(1.0, 1, 1.0), (1.0, 1, 1.0)],
)
# create the Flopy groundwater flow (gwf) model object
model_nam_file = f"{name}.nam"
gwf = flopy.mf6.ModflowGwf(sim, modelname=name, model_nam_file=model_nam_file)
# create the flopy iterative model solver (ims) package object
ims = flopy.mf6.modflow.mfims.ModflowIms(sim, pname="ims", complexity="SIMPLE")
# create the discretization package
bot = np.linspace(-50.0 / 3.0, -3.0, 3)
delrow = delcol = 4.0
dis = flopy.mf6.modflow.mfgwfdis.ModflowGwfdis(
gwf,
pname="dis",
nogrb=True,
nlay=3,
nrow=10,
ncol=10,
delr=delrow,
delc=delcol,
top=0.0,
botm=bot,
)
Setting up a Data Storage Information Dictionary¶
To store data externally add a filename key to the dictionary whose value is the file where you want to store the data. Add a binary key with value True to make the file a binary file. Add a prn key whose value is a format code to set the format code for the data. For array data add a factor key whose value is a positive floating point number to add a factor/multiplier for the array.
Below a dictionary is created that defines how a k33 array will be stored. The dictionary specifies that the k33 array be stored in the binary file k33.txt with a factor of 1.0 applied to the array and a print code of 1. The k33 array data is constructed as a numpy array.
[5]:
k33_values = np.full((3, 10, 10), 1.1)
k33 = {
"filename": "k33.txt",
"factor": 1.0,
"data": k33_values,
"iprn": 1,
"binary": "True",
}
The NPF package is then created with the k33 array in an external binary file. This binary file is created when the simulation method write_simulation is called.
[6]:
npf = flopy.mf6.ModflowGwfnpf(
gwf,
pname="npf",
save_flows=True,
icelltype=[1, 1, 1],
k=10.0,
k22=5.0,
k33=k33,
xt3doptions="xt3d rhs",
rewet_record="REWET WETFCT 1.0 IWETIT 1 IHDWET 0",
)
<flopy.mf6.data.mfstructure.MFDataItemStructure object at 0x7f6bd6393100>
<flopy.mf6.data.mfstructure.MFDataItemStructure object at 0x7f6bd6393130>
External files can be set for specific layers of data. If we want to store the bottom elevations for the third model layer to an external file, then the dictionary that we pass in for the third layer can be given a “filename” key.
[7]:
a0 = {"factor": 0.5, "iprn": 1, "data": np.ones((10, 10))}
a1 = -100
a2 = {
"filename": "dis.botm.3.txt",
"factor": 2.0,
"iprn": 1,
"data": -100 * np.ones((10, 10)),
}
A list containing data for the three specified layers is then passed in to the botm object’s set_data method.
[8]:
dis.botm.set_data([a0, a1, a2])
print(dis.botm.get_file_entry())
botm LAYERED
INTERNAL FACTOR 0.5 IPRN 1
1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000
1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000
1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000
1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000
1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000
1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000
1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000
1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000
1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000
1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000 1.00000000
CONSTANT -100.00000000
OPEN/CLOSE 'dis.botm.3.txt' FACTOR 2.0 IPRN 1
Note that we could have also specified botm this way as part of the original flopy.mf6.ModflowGwfdis constructor:
[9]:
a0 = {"factor": 0.5, "iprn": 1, "data": np.ones((10, 10))}
a1 = -100
a2 = {
"filename": "dis.botm.3.bin",
"factor": 2.0,
"iprn": 1,
"data": -100 * np.ones((4, 5)),
"binary": True,
}
botm = [a0, a1, a2]
flopy.mf6.ModflowGwfdis(gwf, nlay=3, nrow=10, ncol=10, botm=botm)
WARNING: Package with type dis already exists. Replacing existing package.
[9]:
package_name = dis
filename = example_1.dis
package_type = dis
model_or_simulation_package = model
model_name = example_1
Block dimensions
--------------------
nlay
{internal}
(3)
nrow
{internal}
(10)
ncol
{internal}
(10)
Block griddata
--------------------
delr
{constant 1.0}
delc
{constant 1.0}
top
{constant 1.0}
botm
Layer_1{internal, factor 0.5, iprn 1}
(array([[1., 1., 1., 1., 1., 1., 1., 1., 1., 1.],
[1., 1., 1., 1., 1., 1., 1., 1., 1., 1.],
[1., 1., 1., 1., 1., 1., 1., 1., 1., 1.],
[1., 1., 1., 1., 1., 1., 1., 1., 1., 1.],
[1., 1., 1., 1., 1., 1., 1., 1., 1., 1.],
[1., 1., 1., 1., 1., 1., 1., 1., 1., 1.],
[1., 1., 1., 1., 1., 1., 1., 1., 1., 1.],
[1., 1., 1., 1., 1., 1., 1., 1., 1., 1.],
[1., 1., 1., 1., 1., 1., 1., 1., 1., 1.],
[1., 1., 1., 1., 1., 1., 1., 1., 1., 1.]]))
Layer_2{constant -100}