SWI - single layer

A single confined layer. GHB on the LHS representing an ocean bcn. WEL on the RHS representing the freshwater coming from land. One stress period is defined of perlen days and is devided into nstp time steps and only the solution at the end of the stress period is written as output. bdestombe@gmail.com

This version shows an confined aquifer, freshwater heads are around 0m. The initial zeta surface is placed a little bit above the bottom of the single aquifer. The interface is at steady state (tscale 100 changed to 1000 gave no difference). The interface is not able to move upwards, but the interface does move down if placed above the BGH solution. Especially remarkable is the small dip in the heel.

Changing the initial zeta condition such that the first zini value (all the way on the left) reaches the top of the aquifer, lets the SWI solution follow the BGH solution. If you move this cell to the right the swi solution gets off more ( zeta is lower)


In [1]:
%matplotlib inline
import os
import sys
import numpy as np
import flopy.modflow as mf
import flopy.utils as fu
import matplotlib.pyplot as plt

Paths


In [2]:
os.chdir('C:\\Users\\Bas\\Google Drive\\USGS\\FloPy\\slope1D')
sys.path.append('C:\\Users\\Bas\\Google Drive\\USGS\\FloPy\\basScript') # location of gridObj

modelname 	= 'run1swi2'
exe_name 	= 'mf2005'
workspace 	= 'data'

Model input


In [3]:
ml = mf.Modflow(modelname, exe_name=exe_name, model_ws=workspace)

Test variables


In [4]:
tscale	= 1.
nstp 	= tscale * 1000. 			#[]
perlen 	= tscale * 365. * 200. 	#[d]
ssz 	= 0.2 			#[]
Q 		= 0.001 	 	#[m3/d]

Discretization data


In [5]:
nlay = 1
nrow = 1
ncol = 200#4
delr = 1.#[20.,25.,30.,35.]
delc = 1.

topL = -20.
topR = -15.
botL = -21.

iGHB = np.arange(30)

TOP  = np.linspace(topL,topL,ncol).reshape((nrow,ncol))
BOTM = np.array(botL+TOP-topL).reshape((nlay,nrow,ncol))

TOP[0,np.arange(iGHB.max(),ncol)] = np.linspace(topL,topR,ncol-iGHB.max())
BOTM = np.array(botL+TOP-topL).reshape((nlay,nrow,ncol))

save_head_every=1

BCN: WEL


In [6]:
lrcQ1 = np.array([(0, 0, 199, Q)]) #LRCQ, Q[m**3/d]

BCN: GHB


In [7]:
lrchc 					= np.zeros((30, 5))
lrchc[:, [0, 1, 3, 4]] 	= [0, 0, -topL*0.025, 0.8 / 2.0 * delc]
lrchc[:, 2] 			= np.arange(0, 30)
#print lrchc, topL

SWI2


In [8]:
#zini 	= np.hstack(( topL * np.ones(24), np.arange(topL, botL, -0.5), botL * np.ones(94)))[np.newaxis, :] # (nrow,ncol)
zini 	= botL*np.ones((1, ncol), dtype=np.float)+0.2
#zini[0,0] = topL #<<<========================================================================================================<<
isource = np.zeros((1, ncol), dtype=np.int)
isource[:, :30] = -2
imax = (BOTM[0,0,-1]-BOTM[0,0,-2])/delr

Model objects


In [9]:
ml = mf.Modflow(modelname, version='mf2005', exe_name=exe_name)
discret = mf.ModflowDis(ml, nrow=nrow, ncol=ncol, nlay=nlay, delr=delr, delc=delc,
                        laycbd=[0], top=TOP, botm=BOTM,
                        nper=1, perlen=perlen, nstp=nstp)
bas = mf.ModflowBas(ml, ibound=1, strt=1.0)
bcf = mf.ModflowBcf(ml, laycon=[0], tran=[4.0])
wel = mf.ModflowWel(ml, stress_period_data={0:lrcQ1})
ghb = mf.ModflowGhb(ml, stress_period_data={0:lrchc})
swi = mf.ModflowSwi2(ml, nsrf=1, istrat=1, toeslope=0.02, tipslope=0.04, nu=[0, 0.025],
                     zeta=[zini], ssz=ssz, isource=isource, nsolver=1)
oc  = mf.ModflowOc(ml, save_head_every=nstp)
pcg = mf.ModflowPcg(ml)

In [10]:
ml.write_input() #--write the model files

Run the model


In [11]:
m = ml.run_model(silent=True, report=True)

Read the output

only one head entry and one zeta entry in binary files


In [12]:
headfile = modelname + '.hds'
hdobj = fu.HeadFile(headfile)
head = hdobj.get_data(idx=0)

In [13]:
zetafile = modelname + '.zta'
zobj = fu.CellBudgetFile(zetafile)
zeta = zobj.get_data(idx=0, text='      ZETASRF  1')[0]

Plot


In [14]:
import gridobj as grd
gr = grd.gridobj(discret)

In [15]:
fig = plt.figure(figsize=(20, 8), dpi=300, facecolor='w', edgecolor='k')
ax = fig.add_subplot(111)
ax.plot(gr.cGr[0,:-1],TOP.squeeze(),drawstyle='steps-post')
ax.plot(gr.cGr[0,:-1],BOTM.squeeze(),drawstyle='steps-post')
ax.plot(gr.cGr[0,:-1],zini[0,:], drawstyle='steps-post',label='Initial')
ax.plot(gr.cGr[0,:-1],zeta[0,0,:],drawstyle='steps-post', label='SWI2')
ax.plot(gr.cGr[0,:-1],head[0, 0, :], label='feshw head')
ax.plot(gr.cGr[0,:-1],TOP[:,0] - 40. * (head[0, 0, :]), label='Ghyben-Herzberg')
ax.axis(gr.limLC([0,-120.,-0.5,-4.5]))
leg = ax.legend(loc='lower left', numpoints=1)
leg._drawFrame = False



In [16]:
plt.plot(gr.cGr[0,:-1],zini[0,:]-zeta[0,0,:])


Out[16]:
[<matplotlib.lines.Line2D at 0xa122f98>]
                  VOLUMETRIC SWI ZONE BUDGET FOR ENTIRE MODEL
                 AT END OF TIME STEP 1000 IN STRESS PERIOD   1
                                  ZONE     1

    CUMULATIVE VOLUMES      L**3       RATES FOR THIS TIME STEP      L**3/T
    ------------------                 ------------------------

          IN:                                      IN:
          ---                                      ---
         BOUNDARIES =          73.0006            BOUNDARIES =       1.0000E-03
      CONSTANT HEAD =           0.0000         CONSTANT HEAD =           0.0000
        ZONE CHANGE =       7.0380E-02           ZONE CHANGE =           0.0000
   ZONE CHG TIP/TOE =       6.3133E-04      ZONE CHG TIP/TOE =           0.0000
        ZONE MIXING =           0.0000           ZONE MIXING =           0.0000

           TOTAL IN =          73.0716              TOTAL IN =       1.0000E-03

         OUT:                                     OUT:
         ----                                     ----
         BOUNDARIES =          73.0006            BOUNDARIES =       1.0000E-03
      CONSTANT HEAD =           0.0000         CONSTANT HEAD =           0.0000
        ZONE CHANGE =       7.0286E-02           ZONE CHANGE =           0.0000
   ZONE CHG TIP/TOE =       6.3133E-04      ZONE CHG TIP/TOE =           0.0000
        ZONE MIXING =           0.0000           ZONE MIXING =           0.0000

          TOTAL OUT =          73.0715             TOTAL OUT =       1.0000E-03

           IN - OUT =       8.3923E-05              IN - OUT =       2.3283E-10

PERCENT DISCREPANCY =           0.00     PERCENT DISCREPANCY =           0.00



                  VOLUMETRIC SWI ZONE BUDGET FOR ENTIRE MODEL
                 AT END OF TIME STEP 1000 IN STRESS PERIOD   1
                                  ZONE     2

    CUMULATIVE VOLUMES      L**3       RATES FOR THIS TIME STEP      L**3/T
    ------------------                 ------------------------

          IN:                                      IN:
          ---                                      ---
         BOUNDARIES =           0.0000            BOUNDARIES =           0.0000
      CONSTANT HEAD =           0.0000         CONSTANT HEAD =           0.0000
        ZONE CHANGE =       6.9655E-02           ZONE CHANGE =           0.0000
   ZONE CHG TIP/TOE =       6.3133E-04      ZONE CHG TIP/TOE =           0.0000
        ZONE MIXING =           0.0000           ZONE MIXING =           0.0000

           TOTAL IN =       7.0286E-02              TOTAL IN =           0.0000

         OUT:                                     OUT:
         ----                                     ----
         BOUNDARIES =           0.0000            BOUNDARIES =           0.0000
      CONSTANT HEAD =           0.0000         CONSTANT HEAD =           0.0000
        ZONE CHANGE =       7.0380E-02           ZONE CHANGE =           0.0000
   ZONE CHG TIP/TOE =           0.0000      ZONE CHG TIP/TOE =           0.0000
        ZONE MIXING =           0.0000           ZONE MIXING =           0.0000

          TOTAL OUT =       7.0380E-02             TOTAL OUT =           0.0000

           IN - OUT =      -9.4227E-05              IN - OUT =           0.0000

PERCENT DISCREPANCY =          -0.13     PERCENT DISCREPANCY =           0.00


HEAD WILL BE SAVED ON UNIT 51 AT END OF TIME STEP 1000, STRESS PERIOD 1 1

VOLUMETRIC BUDGET FOR ENTIRE MODEL AT END OF TIME STEP 1000, STRESS PERIOD 1

 CUMULATIVE VOLUMES      L**3       RATES FOR THIS TIME STEP      L**3/T
 ------------------                 ------------------------

       IN:                                      IN:
       ---                                      ---
         STORAGE =           0.0000               STORAGE =           0.0000
   CONSTANT HEAD =           0.0000         CONSTANT HEAD =           0.0000
           WELLS =          73.0006                 WELLS =       1.0000E-03
 HEAD DEP BOUNDS =           0.0000       HEAD DEP BOUNDS =           0.0000
      SWIADDTOCH =           0.0000            SWIADDTOCH =           0.0000

        TOTAL IN =          73.0006              TOTAL IN =       1.0000E-03

      OUT:                                     OUT:
      ----                                     ----
         STORAGE =           0.0000               STORAGE =           0.0000
   CONSTANT HEAD =           0.0000         CONSTANT HEAD =           0.0000
           WELLS =           0.0000                 WELLS =           0.0000
 HEAD DEP BOUNDS =          73.0006       HEAD DEP BOUNDS =       1.0000E-03
      SWIADDTOCH =           0.0000            SWIADDTOCH =           0.0000

       TOTAL OUT =          73.0006             TOTAL OUT =       1.0000E-03

        IN - OUT =      -1.5259E-05              IN - OUT =       2.3283E-10

PERCENT DISCREPANCY = -0.00 PERCENT DISCREPANCY = 0.00


In [16]: