totim not found in fp.utils.binaryfile.HeadFile.get_data()

[QingHe-UT]

Hi all,

I'm following MODFLOW Tutorial 2: Unconfined Transient Flow Model with modflow6 (modflow2005 is used in the tutorial). The simulations are run successfully, but when I tried to plot the results for different time step, an error occurred as "Exception: totim value (101.0) not found in file..."

I've tested the plotting code with the results by modflow2005 and it works good. So I was wondering is there anything wrong with my code used here and is there any difference between modflow6 and 2005 when processing timestep information of the results?

The time discretization I used for the simulations is:
#stress period (for time variant model)
nper = 3 #total stress period
pdata1 = (1,1,1.0) #perlen,nstp,tsmult
pdata2 = (100, 100, 1.2)
pdata3 = (100, 100, 1.2)
steady = [True, False, False] #True for steady-state sim, False for time-variant sim

#time discretization
tdis = fp.mf6.ModflowTdis(sim, time_units = 'DAYS', nper = nper, perioddata = (pdata1,pdata2,pdata3))

And the plot code I use is:
#plot
fname = os.path.join(modelws, f"{modelname}.hds") #access the output head file
headobj = fp.utils.binaryfile.HeadFile(fname)
head = headobj.get_data(mflay = 0)
#headobj.list_records()
#times = headobj.get_times()
rec = headobj.get_data(totim=101.)

Then I checked the list_record of the simulated water head, it does contain the time step information I requested, as:

(1, 1, 1., 1., b'HEAD ', 10, 10, 1)
(1, 2, 2.41493472e-07, 1.00000024, b'HEAD ', 10, 10, 1)
(2, 2, 5.31285639e-07, 1.00000053, b'HEAD ', 10, 10, 1)
(3, 2, 8.79036239e-07, 1.00000088, b'HEAD ', 10, 10, 1)
(4, 2, 1.29633696e-06, 1.0000013, b'HEAD ', 10, 10, 1)
(5, 2, 1.79709782e-06, 1.0000018, b'HEAD ', 10, 10, 1)
(6, 2, 2.39801086e-06, 1.0000024, b'HEAD ', 10, 10, 1)
(7, 2, 3.11910651e-06, 1.00000312, b'HEAD ', 10, 10, 1)
(8, 2, 3.98442128e-06, 1.00000398, b'HEAD ', 10, 10, 1)
(9, 2, 5.02279901e-06, 1.00000502, b'HEAD ', 10, 10, 1)
(10, 2, 6.26885228e-06, 1.00000627, b'HEAD ', 10, 10, 1)
(11, 2, 7.76411621e-06, 1.00000776, b'HEAD ', 10, 10, 1)
(12, 2, 9.55843292e-06, 1.00000956, b'HEAD ', 10, 10, 1)
(13, 2, 1.1711613e-05, 1.00001171, b'HEAD ', 10, 10, 1)
(14, 2, 1.42954291e-05, 1.0000143, b'HEAD ', 10, 10, 1)
(15, 2, 1.73960083e-05, 1.0000174, b'HEAD ', 10, 10, 1)
(16, 2, 2.11167035e-05, 1.00002112, b'HEAD ', 10, 10, 1)
(17, 2, 2.55815376e-05, 1.00002558, b'HEAD ', 10, 10, 1)
(18, 2, 3.09393386e-05, 1.00003094, b'HEAD ', 10, 10, 1)
(19, 2, 3.73686998e-05, 1.00003737, b'HEAD ', 10, 10, 1)
(20, 2, 4.50839333e-05, 1.00004508, b'HEAD ', 10, 10, 1)
(21, 2, 5.43422134e-05, 1.00005434, b'HEAD ', 10, 10, 1)
(22, 2, 6.54521496e-05, 1.00006545, b'HEAD ', 10, 10, 1)
(23, 2, 7.87840729e-05, 1.00007878, b'HEAD ', 10, 10, 1)
(24, 2, 9.4782381e-05, 1.00009478, b'HEAD ', 10, 10, 1)
(25, 2, 0.00011398, 1.00011398, b'HEAD ', 10, 10, 1)
(26, 2, 0.00013702, 1.00013702, b'HEAD ', 10, 10, 1)
(27, 2, 0.00016466, 1.00016466, b'HEAD ', 10, 10, 1)
(28, 2, 0.00019784, 1.00019784, b'HEAD ', 10, 10, 1)
(29, 2, 0.00023765, 1.00023765, b'HEAD ', 10, 10, 1)
(30, 2, 0.00028542, 1.00028542, b'HEAD ', 10, 10, 1)
(31, 2, 0.00034274, 1.00034274, b'HEAD ', 10, 10, 1)
(32, 2, 0.00041153, 1.00041153, b'HEAD ', 10, 10, 1)
(33, 2, 0.00049408, 1.00049408, b'HEAD ', 10, 10, 1)
(34, 2, 0.00059314, 1.00059314, b'HEAD ', 10, 10, 1)
(35, 2, 0.00071201, 1.00071201, b'HEAD ', 10, 10, 1)
(36, 2, 0.00085465, 1.00085465, b'HEAD ', 10, 10, 1)
(37, 2, 0.00102582, 1.00102582, b'HEAD ', 10, 10, 1)
(38, 2, 0.00123122, 1.00123122, b'HEAD ', 10, 10, 1)
(39, 2, 0.00147771, 1.00147771, b'HEAD ', 10, 10, 1)
(40, 2, 0.00177349, 1.00177349, b'HEAD ', 10, 10, 1)
(41, 2, 0.00212843, 1.00212843, b'HEAD ', 10, 10, 1)
(42, 2, 0.00255436, 1.00255436, b'HEAD ', 10, 10, 1)
(43, 2, 0.00306548, 1.00306548, b'HEAD ', 10, 10, 1)
(44, 2, 0.00367881, 1.00367881, b'HEAD ', 10, 10, 1)
(45, 2, 0.00441482, 1.00441482, b'HEAD ', 10, 10, 1)
(46, 2, 0.00529802, 1.00529802, b'HEAD ', 10, 10, 1)
(47, 2, 0.00635787, 1.00635787, b'HEAD ', 10, 10, 1)
(48, 2, 0.00762968, 1.00762968, b'HEAD ', 10, 10, 1)
(49, 2, 0.00915586, 1.00915586, b'HEAD ', 10, 10, 1)
(50, 2, 0.01098727, 1.01098727, b'HEAD ', 10, 10, 1)
(51, 2, 0.01318497, 1.01318497, b'HEAD ', 10, 10, 1)
(52, 2, 0.01582221, 1.01582221, b'HEAD ', 10, 10, 1)
(53, 2, 0.01898689, 1.01898689, b'HEAD ', 10, 10, 1)
(54, 2, 0.02278451, 1.02278451, b'HEAD ', 10, 10, 1)
(55, 2, 0.02734165, 1.02734165, b'HEAD ', 10, 10, 1)
(56, 2, 0.03281022, 1.03281022, b'HEAD ', 10, 10, 1)
(57, 2, 0.03937251, 1.03937251, b'HEAD ', 10, 10, 1)
(58, 2, 0.04724725, 1.04724725, b'HEAD ', 10, 10, 1)
(59, 2, 0.05669695, 1.05669695, b'HEAD ', 10, 10, 1)
(60, 2, 0.06803658, 1.06803658, b'HEAD ', 10, 10, 1)
(61, 2, 0.08164413, 1.08164413, b'HEAD ', 10, 10, 1)
(62, 2, 0.0979732, 1.0979732, b'HEAD ', 10, 10, 1)
(63, 2, 0.11756808, 1.11756808, b'HEAD ', 10, 10, 1)
(64, 2, 0.14108194, 1.14108194, b'HEAD ', 10, 10, 1)
(65, 2, 0.16929857, 1.16929857, b'HEAD ', 10, 10, 1)
(66, 2, 0.20315853, 1.20315853, b'HEAD ', 10, 10, 1)
(67, 2, 0.24379048, 1.24379048, b'HEAD ', 10, 10, 1)
(68, 2, 0.29254881, 1.29254881, b'HEAD ', 10, 10, 1)
(69, 2, 0.35105882, 1.35105882, b'HEAD ', 10, 10, 1)
(70, 2, 0.42127082, 1.42127082, b'HEAD ', 10, 10, 1)
(71, 2, 0.50552523, 1.50552523, b'HEAD ', 10, 10, 1)
(72, 2, 0.60663051, 1.60663051, b'HEAD ', 10, 10, 1)
(73, 2, 0.72795686, 1.72795686, b'HEAD ', 10, 10, 1)
(74, 2, 0.87354847, 1.87354847, b'HEAD ', 10, 10, 1)
(75, 2, 1.04825841, 2.04825841, b'HEAD ', 10, 10, 1)
(76, 2, 1.25791033, 2.25791033, b'HEAD ', 10, 10, 1)
(77, 2, 1.50949264, 2.50949264, b'HEAD ', 10, 10, 1)
(78, 2, 1.81139141, 2.81139141, b'HEAD ', 10, 10, 1)
(79, 2, 2.17366993, 3.17366993, b'HEAD ', 10, 10, 1)
(80, 2, 2.60840415, 3.60840415, b'HEAD ', 10, 10, 1)
(81, 2, 3.13008523, 4.13008523, b'HEAD ', 10, 10, 1)
(82, 2, 3.75610251, 4.75610251, b'HEAD ', 10, 10, 1)
(83, 2, 4.50732326, 5.50732326, b'HEAD ', 10, 10, 1)
(84, 2, 5.40878815, 6.40878815, b'HEAD ', 10, 10, 1)
(85, 2, 6.49054602, 7.49054602, b'HEAD ', 10, 10, 1)
(86, 2, 7.78865547, 8.78865547, b'HEAD ', 10, 10, 1)
(87, 2, 9.3463868, 10.3463868, b'HEAD ', 10, 10, 1)
(88, 2, 11.21566441, 12.21566441, b'HEAD ', 10, 10, 1)
(89, 2, 13.45879753, 14.45879753, b'HEAD ', 10, 10, 1)
(90, 2, 16.15055728, 17.15055728, b'HEAD ', 10, 10, 1)
(91, 2, 19.38066897, 20.38066897, b'HEAD ', 10, 10, 1)
(92, 2, 23.25680301, 24.25680301, b'HEAD ', 10, 10, 1)
(93, 2, 27.90816385, 28.90816385, b'HEAD ', 10, 10, 1)
(94, 2, 33.48979686, 34.48979686, b'HEAD ', 10, 10, 1)
(95, 2, 40.18775648, 41.18775648, b'HEAD ', 10, 10, 1)
(96, 2, 48.22530802, 49.22530802, b'HEAD ', 10, 10, 1)
(97, 2, 57.87036986, 58.87036986, b'HEAD ', 10, 10, 1)
(98, 2, 69.44444408, 70.44444408, b'HEAD ', 10, 10, 1)
(99, 2, 83.33333313, 84.33333313, b'HEAD ', 10, 10, 1)
(100, 2, 100., 101., b'HEAD ', 10, 10, 1)
(1, 3, 2.41493472e-07, 101.00000024, b'HEAD ', 10, 10, 1)
(2, 3, 5.31285639e-07, 101.00000053, b'HEAD ', 10, 10, 1)
(3, 3, 8.79036239e-07, 101.00000088, b'HEAD ', 10, 10, 1)
(4, 3, 1.29633696e-06, 101.0000013, b'HEAD ', 10, 10, 1)
(5, 3, 1.79709782e-06, 101.0000018, b'HEAD ', 10, 10, 1)
(6, 3, 2.39801086e-06, 101.0000024, b'HEAD ', 10, 10, 1)
(7, 3, 3.11910651e-06, 101.00000312, b'HEAD ', 10, 10, 1)
(8, 3, 3.98442128e-06, 101.00000398, b'HEAD ', 10, 10, 1)
(9, 3, 5.02279901e-06, 101.00000502, b'HEAD ', 10, 10, 1)
(10, 3, 6.26885228e-06, 101.00000627, b'HEAD ', 10, 10, 1)
(11, 3, 7.76411621e-06, 101.00000776, b'HEAD ', 10, 10, 1)
(12, 3, 9.55843292e-06, 101.00000956, b'HEAD ', 10, 10, 1)
(13, 3, 1.1711613e-05, 101.00001171, b'HEAD ', 10, 10, 1)
(14, 3, 1.42954291e-05, 101.0000143, b'HEAD ', 10, 10, 1)
(15, 3, 1.73960083e-05, 101.0000174, b'HEAD ', 10, 10, 1)
(16, 3, 2.11167035e-05, 101.00002112, b'HEAD ', 10, 10, 1)
(17, 3, 2.55815376e-05, 101.00002558, b'HEAD ', 10, 10, 1)
(18, 3, 3.09393386e-05, 101.00003094, b'HEAD ', 10, 10, 1)
(19, 3, 3.73686998e-05, 101.00003737, b'HEAD ', 10, 10, 1)
(20, 3, 4.50839333e-05, 101.00004508, b'HEAD ', 10, 10, 1)
(21, 3, 5.43422134e-05, 101.00005434, b'HEAD ', 10, 10, 1)
(22, 3, 6.54521496e-05, 101.00006545, b'HEAD ', 10, 10, 1)
(23, 3, 7.87840729e-05, 101.00007878, b'HEAD ', 10, 10, 1)
(24, 3, 9.4782381e-05, 101.00009478, b'HEAD ', 10, 10, 1)
(25, 3, 0.00011398, 101.00011398, b'HEAD ', 10, 10, 1)
(26, 3, 0.00013702, 101.00013702, b'HEAD ', 10, 10, 1)
(27, 3, 0.00016466, 101.00016466, b'HEAD ', 10, 10, 1)
(28, 3, 0.00019784, 101.00019784, b'HEAD ', 10, 10, 1)
(29, 3, 0.00023765, 101.00023765, b'HEAD ', 10, 10, 1)
(30, 3, 0.00028542, 101.00028542, b'HEAD ', 10, 10, 1)
(31, 3, 0.00034274, 101.00034274, b'HEAD ', 10, 10, 1)
(32, 3, 0.00041153, 101.00041153, b'HEAD ', 10, 10, 1)
(33, 3, 0.00049408, 101.00049408, b'HEAD ', 10, 10, 1)
(34, 3, 0.00059314, 101.00059314, b'HEAD ', 10, 10, 1)
(35, 3, 0.00071201, 101.00071201, b'HEAD ', 10, 10, 1)
(36, 3, 0.00085465, 101.00085465, b'HEAD ', 10, 10, 1)
(37, 3, 0.00102582, 101.00102582, b'HEAD ', 10, 10, 1)
(38, 3, 0.00123122, 101.00123122, b'HEAD ', 10, 10, 1)
(39, 3, 0.00147771, 101.00147771, b'HEAD ', 10, 10, 1)
(40, 3, 0.00177349, 101.00177349, b'HEAD ', 10, 10, 1)
(41, 3, 0.00212843, 101.00212843, b'HEAD ', 10, 10, 1)
(42, 3, 0.00255436, 101.00255436, b'HEAD ', 10, 10, 1)
(43, 3, 0.00306548, 101.00306548, b'HEAD ', 10, 10, 1)
(44, 3, 0.00367881, 101.00367881, b'HEAD ', 10, 10, 1)
(45, 3, 0.00441482, 101.00441482, b'HEAD ', 10, 10, 1)
(46, 3, 0.00529802, 101.00529802, b'HEAD ', 10, 10, 1)
(47, 3, 0.00635787, 101.00635787, b'HEAD ', 10, 10, 1)
(48, 3, 0.00762968, 101.00762968, b'HEAD ', 10, 10, 1)
(49, 3, 0.00915586, 101.00915586, b'HEAD ', 10, 10, 1)
(50, 3, 0.01098727, 101.01098727, b'HEAD ', 10, 10, 1)
(51, 3, 0.01318497, 101.01318497, b'HEAD ', 10, 10, 1)
(52, 3, 0.01582221, 101.01582221, b'HEAD ', 10, 10, 1)
(53, 3, 0.01898689, 101.01898689, b'HEAD ', 10, 10, 1)
(54, 3, 0.02278451, 101.02278451, b'HEAD ', 10, 10, 1)
(55, 3, 0.02734165, 101.02734165, b'HEAD ', 10, 10, 1)
(56, 3, 0.03281022, 101.03281022, b'HEAD ', 10, 10, 1)
(57, 3, 0.03937251, 101.03937251, b'HEAD ', 10, 10, 1)
(58, 3, 0.04724725, 101.04724725, b'HEAD ', 10, 10, 1)
(59, 3, 0.05669695, 101.05669695, b'HEAD ', 10, 10, 1)
(60, 3, 0.06803658, 101.06803658, b'HEAD ', 10, 10, 1)
(61, 3, 0.08164413, 101.08164413, b'HEAD ', 10, 10, 1)
(62, 3, 0.0979732, 101.0979732, b'HEAD ', 10, 10, 1)
(63, 3, 0.11756808, 101.11756808, b'HEAD ', 10, 10, 1)
(64, 3, 0.14108194, 101.14108194, b'HEAD ', 10, 10, 1)
(65, 3, 0.16929857, 101.16929857, b'HEAD ', 10, 10, 1)
(66, 3, 0.20315853, 101.20315853, b'HEAD ', 10, 10, 1)
(67, 3, 0.24379048, 101.24379048, b'HEAD ', 10, 10, 1)
(68, 3, 0.29254881, 101.29254881, b'HEAD ', 10, 10, 1)
(69, 3, 0.35105882, 101.35105882, b'HEAD ', 10, 10, 1)
(70, 3, 0.42127082, 101.42127082, b'HEAD ', 10, 10, 1)
(71, 3, 0.50552523, 101.50552523, b'HEAD ', 10, 10, 1)
(72, 3, 0.60663051, 101.60663051, b'HEAD ', 10, 10, 1)
(73, 3, 0.72795686, 101.72795686, b'HEAD ', 10, 10, 1)
(74, 3, 0.87354847, 101.87354847, b'HEAD ', 10, 10, 1)
(75, 3, 1.04825841, 102.04825841, b'HEAD ', 10, 10, 1)
(76, 3, 1.25791033, 102.25791033, b'HEAD ', 10, 10, 1)
(77, 3, 1.50949264, 102.50949264, b'HEAD ', 10, 10, 1)
(78, 3, 1.81139141, 102.81139141, b'HEAD ', 10, 10, 1)
(79, 3, 2.17366993, 103.17366993, b'HEAD ', 10, 10, 1)
(80, 3, 2.60840415, 103.60840415, b'HEAD ', 10, 10, 1)
(81, 3, 3.13008523, 104.13008523, b'HEAD ', 10, 10, 1)
(82, 3, 3.75610251, 104.75610251, b'HEAD ', 10, 10, 1)
(83, 3, 4.50732326, 105.50732326, b'HEAD ', 10, 10, 1)
(84, 3, 5.40878815, 106.40878815, b'HEAD ', 10, 10, 1)
(85, 3, 6.49054602, 107.49054602, b'HEAD ', 10, 10, 1)
(86, 3, 7.78865547, 108.78865547, b'HEAD ', 10, 10, 1)
(87, 3, 9.3463868, 110.3463868, b'HEAD ', 10, 10, 1)
(88, 3, 11.21566441, 112.21566441, b'HEAD ', 10, 10, 1)
(89, 3, 13.45879753, 114.45879753, b'HEAD ', 10, 10, 1)
(90, 3, 16.15055728, 117.15055728, b'HEAD ', 10, 10, 1)
(91, 3, 19.38066897, 120.38066897, b'HEAD ', 10, 10, 1)
(92, 3, 23.25680301, 124.25680301, b'HEAD ', 10, 10, 1)
(93, 3, 27.90816385, 128.90816385, b'HEAD ', 10, 10, 1)
(94, 3, 33.48979686, 134.48979686, b'HEAD ', 10, 10, 1)
(95, 3, 40.18775648, 141.18775648, b'HEAD ', 10, 10, 1)
(96, 3, 48.22530802, 149.22530802, b'HEAD ', 10, 10, 1)
(97, 3, 57.87036986, 158.87036986, b'HEAD ', 10, 10, 1)
(98, 3, 69.44444408, 170.44444408, b'HEAD ', 10, 10, 1)
(99, 3, 83.33333313, 184.33333313, b'HEAD ', 10, 10, 1)
(100, 3, 100., 201., b'HEAD ', 10, 10, 1)

The error information then occurred:

Exception Traceback (most recent call last)
Cell In[283], line 7
5 headobj.list_records()
6 #times = headobj.get_times()
----> 7 rec = headobj.get_data(totim=101.)
8 #cbb = fp.utils.CellBudgetFile("./toy_tvar_mf05/modflowtest.cbc")

File /Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/flopy/utils/datafile.py:532, in LayerFile.get_data(self, kstpkper, idx, totim, mflay)
529 else:
530 totim1 = self.times[-1]
--> 532 data = self._get_data_array(totim1)
533 if mflay is None:
534 return data

File /Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/flopy/utils/datafile.py:428, in LayerFile._get_data_array(self, totim)
426 if len(keyindices) == 0:
427 msg = f"totim value ({totim}) not found in file..."
--> 428 raise Exception(msg)
429 else:
430 raise Exception("Data not found...")

Exception: totim value (101.0) not found in file...

[mbakker7]

In MF6, you can get the heads data in a much easier way than in mf2005 and then get the stored times. For example, if your groundwater flow model object is called gwf, you can do

hds = gwf.output.head() # get handle to binary head file
times = hds.get_times()

You can see whether totim=101 is indeed stored. You are using a time step multiplier of 1.2, which means that the times are likely not nice round numbers. Another problem can be roundoff errors. But you can find out all those by using the get_times function.

[QingHe-UT]

Thank you for your reply! It does seem to the round number problem (totim = 101.00000024149337 rather than 101.0). Regarding this, I also want to ask how to define the step multiplier (tsmult)?

In flopy.mf6.modflow.mftdis module, it says the multiplier should be described as a relation between time step, total time steps, and period length, as:

Is it necessary to follow exactly the equation here to obtain tsmult or we can also give it an arbitrary value ourselves?

P.S. There seems no such argument in time discretization module in MF2005, why do we need this new function?

[jlarsen-usgs]

@QingHe-UT

Dataset 7 in the DIS Package for MODFLOW 2005 and related products includes the TSMULT parameter, as well as the flopy.modflow.ModflowDis object for MODFLOW 2005 and NWT DIS packages. In fact it's been around since at least MODFLOW 88 (probably longer, but that's the oldest documentation I have). TSMULT is an arbitrary time step multiplier that the user can set; for example if it is set to 1 the time step length will be uniform across a stress period. Setting this to a value greater than one can be useful for simulating abrupt changes in boundary conditions between two stress periods. The equation you show describes TSMULT's relationship to the first timestep within a stress period. Each successive time step length is equivalent to delta_t_i = delta_t_i-1 * tsmult where i is the current timestep.

[QingHe-UT]

Thank you for your explanation! I understand it now :)