FloPy

Using FloPy to simplify the use of the MT3DMS SSM package

A multi-component transport demonstration


In [1]:
import os
import sys
import numpy as np
import flopy

print(sys.version)
print('numpy version: {}'.format(np.__version__))
print('flopy version: {}'.format(flopy.__version__))


3.6.0 |Anaconda 4.3.0 (x86_64)| (default, Dec 23 2016, 13:19:00) 
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)]
numpy version: 1.11.3
flopy version: 3.2.6

First, we will create a simple model structure


In [2]:
nlay, nrow, ncol = 10, 10, 10
perlen = np.zeros((10), dtype=np.float) + 10
nper = len(perlen)

ibound = np.ones((nlay,nrow,ncol), dtype=np.int)

botm = np.arange(-1,-11,-1)
top = 0.

Create the MODFLOW packages


In [3]:
model_ws = 'data'
modelname = 'ssmex'
mf = flopy.modflow.Modflow(modelname, model_ws=model_ws)
dis = flopy.modflow.ModflowDis(mf, nlay=nlay, nrow=nrow, ncol=ncol, 
                               perlen=perlen, nper=nper, botm=botm, top=top, 
                               steady=False)
bas = flopy.modflow.ModflowBas(mf, ibound=ibound, strt=top)
lpf = flopy.modflow.ModflowLpf(mf, hk=100, vka=100, ss=0.00001, sy=0.1)
oc = flopy.modflow.ModflowOc(mf)
pcg = flopy.modflow.ModflowPcg(mf)
rch = flopy.modflow.ModflowRch(mf)

We'll track the cell locations for the SSM data using the MODFLOW boundary conditions.

Get a dictionary (dict) that has the SSM itype for each of the boundary types.


In [4]:
itype = flopy.mt3d.Mt3dSsm.itype_dict()
print(itype)
print(flopy.mt3d.Mt3dSsm.get_default_dtype())
ssm_data = {}


{'CHD': 1, 'BAS6': 1, 'PBC': 1, 'WEL': 2, 'DRN': 3, 'RIV': 4, 'GHB': 5, 'MAS': 15, 'CC': -1}
[('k', '<i8'), ('i', '<i8'), ('j', '<i8'), ('css', '<f4'), ('itype', '<i8')]

Add a general head boundary (ghb). The general head boundary head (bhead) is 0.1 for the first 5 stress periods with a component 1 (comp_1) concentration of 1.0 and a component 2 (comp_2) concentration of 100.0. Then bhead is increased to 0.25 and comp_1 concentration is reduced to 0.5 and comp_2 concentration is increased to 200.0


In [5]:
ghb_data = {}
print(flopy.modflow.ModflowGhb.get_default_dtype())
ghb_data[0] = [(4, 4, 4, 0.1, 1.5)]
ssm_data[0] = [(4, 4, 4, 1.0, itype['GHB'], 1.0, 100.0)]
ghb_data[5] = [(4, 4, 4, 0.25, 1.5)]
ssm_data[5] = [(4, 4, 4, 0.5, itype['GHB'], 0.5, 200.0)]

for k in range(nlay):
    for i in range(nrow):
        ghb_data[0].append((k, i, 0, 0.0, 100.0))
        ssm_data[0].append((k, i, 0, 0.0, itype['GHB'], 0.0, 0.0))
    
ghb_data[5] = [(4, 4, 4, 0.25, 1.5)]
ssm_data[5] = [(4, 4, 4, 0.5, itype['GHB'], 0.5, 200.0)]
for k in range(nlay):
    for i in range(nrow):
        ghb_data[5].append((k, i, 0, -0.5, 100.0))
        ssm_data[5].append((k, i, 0, 0.0, itype['GHB'], 0.0, 0.0))


[('k', '<i8'), ('i', '<i8'), ('j', '<i8'), ('bhead', '<f4'), ('cond', '<f4')]

Add an injection well. The injection rate (flux) is 10.0 with a comp_1 concentration of 10.0 and a comp_2 concentration of 0.0 for all stress periods. WARNING: since we changed the SSM data in stress period 6, we need to add the well to the ssm_data for stress period 6.


In [6]:
wel_data = {}
print(flopy.modflow.ModflowWel.get_default_dtype())
wel_data[0] = [(0, 4, 8, 10.0)]
ssm_data[0].append((0, 4, 8, 10.0, itype['WEL'], 10.0, 0.0))
ssm_data[5].append((0, 4, 8, 10.0, itype['WEL'], 10.0, 0.0))


[('k', '<i8'), ('i', '<i8'), ('j', '<i8'), ('flux', '<f4')]

Add the GHB and WEL packages to the mf MODFLOW object instance.


In [7]:
ghb = flopy.modflow.ModflowGhb(mf, stress_period_data=ghb_data)
wel = flopy.modflow.ModflowWel(mf, stress_period_data=wel_data)

Create the MT3DMS packages


In [8]:
mt = flopy.mt3d.Mt3dms(modflowmodel=mf, modelname=modelname, model_ws=model_ws)
btn = flopy.mt3d.Mt3dBtn(mt, sconc=0, ncomp=2, sconc2=50.0)
adv = flopy.mt3d.Mt3dAdv(mt)
ssm = flopy.mt3d.Mt3dSsm(mt, stress_period_data=ssm_data)
gcg = flopy.mt3d.Mt3dGcg(mt)


User specified FTL file does not exist in model directory
MT3D will not work without a linker file

Let's verify that stress_period_data has the right dtype


In [9]:
print(ssm.stress_period_data.dtype)


[('k', '<i8'), ('i', '<i8'), ('j', '<i8'), ('css', '<f4'), ('itype', '<i8'), ('cssm(01)', '<f4'), ('cssm(02)', '<f4')]

Create the SEAWAT packages


In [10]:
swt = flopy.seawat.Seawat(modflowmodel=mf, mt3dmodel=mt, 
                          modelname=modelname, namefile_ext='nam_swt', model_ws=model_ws)
vdf = flopy.seawat.SeawatVdf(swt, mtdnconc=0, iwtable=0, indense=-1)

In [11]:
mf.write_input()
mt.write_input()
swt.write_input()

And finally, modify the vdf package to fix indense.


In [12]:
fname = modelname + '.vdf'
f = open(os.path.join(model_ws, fname),'r')
lines = f.readlines()
f.close()
f = open(os.path.join(model_ws, fname),'w')
for line in lines:
    f.write(line)
for kper in range(nper):
    f.write("-1\n")
f.close()

In [ ]: