flopy.modflow.mfmnw2 Module¶

class
flopy.modflow.mfmnw2.
Mnw
(wellid, nnodes=1, nper=1, losstype='SKIN', pumploc=0, qlimit=0, ppflag=0, pumpcap=0, rw=1, rskin=2, kskin=10, B=None, C=0, P=2.0, cwc=None, pp=1, k=0, i=0, j=0, ztop=0, zbotm=0, node_data=None, stress_period_data=None, pumplay=0, pumprow=0, pumpcol=0, zpump=None, hlim=None, qcut=None, qfrcmn=None, qfrcmx=None, hlift=None, liftq0=None, liftqmax=None, hwtol=None, liftn=None, qn=None, mnwpackage=None)¶ MultiNode Well object class
Parameters: wellid : int
is the name of the well. This is a unique alphanumeric identification label for each well. The text string is limited to 20 alphanumeric characters. If the name of the well includes spaces, then enclose the name in quotes.
nnodes : int
is the number of cells (nodes) associated with this well. NNODES normally is > 0, but for the case of a vertical borehole, setting NNODES < 0 will allow the user to specify the elevations of the tops and bottoms of well screens or open intervals (rather than grid layer numbers), and the absolute value of NNODES equals the number of open intervals (or well screens) to be specified in dataset 2d. If this option is used, then the model will compute the layers in which the open intervals occur, the lengths of the open intervals, and the relative vertical position of the open interval within a model layer (for example, see figure 14 and related discussion).
losstype : str
is a character flag to determine the userspecified model for well loss (equation 2). Available options (that is, place one of the following approved words in this field) are: NONE there are no well corrections and the head in the well is assumed to equal the head in the cell.
This option (hWELL = hn) is only valid for a singlenode well (NNODES = 1). (This is equivalent to using the original WEL Package of MODFLOW, but specifying the singlenode well within the MNW2 Package enables the use of constraints.)
 THIEM this option allows for only the celltowell correction at the well
based on the Thiem (1906) equation; head in the well is determined from equation 2 as (hWELL = hn + AQn), and the model computes A on the basis of the userspecified well radius (Rw) and previously defined values of cell transmissivity and grid spacing. Coefficients B and C in equation 2 are automatically set = 0.0. User must define Rw in dataset 2c or 2d.
 SKIN this option allows for formation damage or skin corrections at the well:
hWELL = hn + AQn + BQn (from equation 2), where A is determined by the model from the value of Rw, and B is determined by the model from Rskin and Kskin. User must define Rw, Rskin, and Kskin in dataset 2c or 2d.
 GENERAL head loss is defined with coefficients A, B, and C and power exponent P
(hWELL = hn + AQn + BQn + CQnP). A is determined by the model from the value of Rw. User must define Rw, B, C, and P in dataset 2c or 2d. A value of P = 2.0 is suggested if no other data are available (the model allows 1.0 <= P <= 3.5). Entering a value of C = 0 will result in a “linear” model in which the value of B is entered directly (rather than entering properties of the skin, as with the SKIN option).
 SPECIFYcwc the user specifies an effective conductance value
(equivalent to the combined effects of the A, B, and C wellloss coefficients expressed in equation 15) between the well and the cell representing the aquifer, CWC. User must define CWC in dataset 2c or 2d. If there are multiple screens within the grid cell or if partial penetration corrections are to be made, then the effective value of CWC for the node may be further adjusted automatically by MNW2.
pumploc : int
is an integer flag pertaining to the location along the borehole of the pump intake (if any). If PUMPLOC = 0, then either there is no pump or the intake location (or discharge point for an injection well) is assumed to occur above the first active node associated with the multi node well (that is, the node closest to the land surface or to the wellhead). If PUMPLOC > 0, then the cell in which the intake (or outflow) is located will be specified in dataset 2e as a LAYROWCOL grid location. For a vertical well only, specifying PUMPLOC < 0, will enable the option to define the vertical position of the pump intake (or outflow) as an elevation in dataset 2e (for the given spatial grid location [ROWCOL] defined for this well in 2d).
qlimit : int
is an integer flag that indicates whether the water level (head) in the well will be used to constrain the pumping rate. If Qlimit = 0, then there are no constraints for this well. If Qlimit > 0, then pumpage will be limited (constrained) by the water level in the well, and relevant parameters are constant in time and defined below in dataset 2f. If Qlimit < 0, then pumpage will be limited (constrained) by the water level in the well, and relevant parameters can vary with time and are defined for every stress period in dataset 4b.
ppflag : int
is an integer flag that determines whether the calculated head in the well will be corrected for the effect of partial penetration of the well screen in the cell. If PPFLAG = 0, then the head in the well will not be adjusted for the effects of partial penetration. If PPFLAG > 0, then the head in the well will be adjusted for the effects of partial penetration if the section of well containing the well screen is vertical (as indicated by identical rowcolumn locations in the grid). If NNODES < 0 (that is, the open intervals of the well are defined by top and bottom elevations), then the model will automatically calculate the fraction of penetration for each node and the relative vertical position of the well screen. If NNODES > 0, then the fraction of penetration for each node must be defined in dataset 2d (see below) and the well screen will be assumed to be centered vertically within the thickness of the cell (except if the well is located in the uppermost model layer that is under unconfined conditions, in which case the bottom of the well screen will be assumed to be aligned with the bottom boundary of the cell and the assumed length of well screen will be based on the initial head in that cell).
pumpcap : int
is an integer flag and value that determines whether the discharge of a pumping (withdrawal) well (Q < 0.0) will be adjusted for changes in the lift (or total dynamic head) with time. If PUMPCAP = 0, then the discharge from the well will not be adjusted on the basis of changes in lift. If PUMPCAP > 0 for a withdrawal well, then the discharge from the well will be adjusted on the basis of the lift, as calculated from the most recent water level in the well. In this case, data describing the headcapacity relation for the pump must be listed in datasets 2g and 2h, and the use of that relation can be switched on or off for each stress period using a flag in dataset 4a. The number of entries (lines) in dataset 2h corresponds to the value of PUMPCAP. If PUMPCAP does not equal 0, it must be set to an integer value of between 1 and 25, inclusive.
rw : float
radius of the well (losstype == ‘THEIM’, ‘SKIN’, or ‘GENERAL’)
rskin : float
radius to the outer limit of the skin (losstype == ‘SKIN’)
kskin : float
hydraulic conductivity of the skin
B : float
coefficient of the wellloss eqn. (eqn. 2 in MNW2 documentation) (losstype == ‘GENERAL’)
C : float
coefficient of the wellloss eqn. (eqn. 2 in MNW2 documentation) (losstype == ‘GENERAL’)
P : float
coefficient of the wellloss eqn. (eqn. 2 in MNW2 documentation) (losstype == ‘GENERAL’)
cwc : float
celltowell conductance. (losstype == ‘SPECIFYcwc’)
pp : float
fraction of partial penetration for the cell. Only specify if PPFLAG > 0 and NNODES > 0.
k : int
layer index of well (zerobased)
i : int
row index of well (zerobased)
j : int
column index of well (zerobased)
ztop : float
top elevation of open intervals of vertical well.
zbotm : float
bottom elevation of open intervals of vertical well.
node_data : numpy record array
table containing MNW data by node. A blank node_data template can be created via the ModflowMnw2.get_empty_mnw_data() static method.
Note: Variables in dataset 2d (e.g. rw) can be entered as a single value for the entire well (above), or in node_data (or dataset 2d) by node. Variables not in dataset 2d (such as pumplay) can be included in node data for convenience (to allow construction of MNW2 package from a table), but are only written to MNW2 as a single variable. When writing nondataset 2d variables to MNW2 input, the first value for the well will be used.
Other variables (e.g. hlim) can be entered here as constant for all stress periods, or by stress period below in stress_period_data. See MNW2 input instructions for more details.
 Columns are:
 k : int
layer index of well (zerobased)
 i : int
row index of well (zerobased)
 j : int
column index of well (zerobased)
 ztop : float
top elevation of open intervals of vertical well.
 zbotm : float
bottom elevation of open intervals of vertical well.
wellid : str losstyp : str pumploc : int qlimit : int ppflag : int pumpcap : int rw : float rskin : float kskin : float B : float C : float P : float cwc : float pp : float pumplay : int pumprow : int pumpcol : int zpump : float hlim : float qcut : int gfrcmn : float gfrcmx : float hlift : float liftq0 : float liftqmax : float hwtol : float liftn : float qn : float
stress_period_data : numpy record array
table containing MNW pumping data for all stress periods (dataset 4 in the MNW2 input instructions). A blank stress_period_data template can be created via the Mnw.get_empty_stress_period_data() static method. Columns are:
 per : int
stress period
 qdes : float
is the actual (or maximum desired, if constraints are to be applied) volumetric pumping rate (negative for withdrawal or positive for injection) at the well (L3/T). Qdes should be set to 0 for nonpumping wells. If constraints are applied, then the calculated volumetric withdrawal or injection rate may be adjusted to range from 0 to Qdes and is not allowed to switch directions between withdrawal and injection conditions during any stress period. When PUMPCAP > 0, in the first stress period in which Qdes is specified with a negative value, Qdes represents the maximum operating discharge for the pump; in subsequent stress periods, any different negative values of Qdes are ignored, although values are subject to adjustment for CapMult. If Qdes >= 0.0, then pumpcapacity adjustments are not applied.
 capmult : int
is a flag and multiplier for implementing headcapacity relations during a given stress period. Only specify if PUMPCAP > 0 for this well. If CapMult <= 0, then headcapacity relations are ignored for this stress period. If CapMult = 1.0, then headcapacity relations defined in datasets 2g and 2h are used. If CapMult equals any other positive value (for example, 0.6 or 1.1), then headcapacity relations are used but adjusted and shifted by multiplying the discharge value indicated by the headcapacity curve by the value of CapMult.
 cprime : float
is the concentration in the injected fluid. Only specify if Qdes > 0 and GWT process is active.
hlim : float qcut : int qfrcmn : float qfrcmx : float
Note: If auxillary variables are also being used, additional columns for these must be included.
pumplay : int
pumprow : int
pumpcol : int
PUMPLAY, PUMPROW, and PUMPCOL are the layer, row, and column numbers, respectively, of the cell (node) in this multinode well where the pump intake (or outflow) is located. The location defined in dataset 2e should correspond with one of the nodes listed in 2d for this multinode well. These variables are only read if PUMPLOC > 0 in 2b.
zpump : float
is the elevation of the pump intake (or discharge pipe location for an injection well). Zpump is read only if PUMPLOC < 0; in this case, the model assumes that the borehole is vertical and will compute the layer of the grid in which the pump intake is located.
hlim : float
is the limiting water level (head) in the well, which is a minimum for discharging wells and a maximum for injection wells. For example, in a discharging well, when hWELL falls below hlim, the flow from the well is constrained.
qcut : int
is an integer flag that indicates how pumping limits Qfrcmn and Qfrcmx will be specified. If pumping limits are to be specified as a rate (L3/T), then set QCUT > 0; if pumping limits are 52 Revised MultiNode Well (MNW2) Package for MODFLOW GroundWater Flow Model to be specified as a fraction of the specified pumping rate (Qdes), then set QCUT < 0. If there is not a minimum pumping rate below which the pump becomes inactive, then set QCUT = 0.
qfrcmn : float
is the minimum pumping rate or fraction of original pumping rate (a choice that depends on QCUT) that a well must exceed to remain active during a stress period. The absolute value of Qfrcmn must be less than the absolute value of Qfrcmx (defined next). Only specify if QCUT != 0.
qfrcmx : float
is the minimum pumping rate or fraction of original pumping rate that must be exceeded to reactivate a well that had been shut off based on Qfrcmn during a stress period. The absolute value of Qfrcmx must be greater than the absolute value of Qfrcmn. Only specify if QCUT != 0.
hlift : float
is the reference head (or elevation) corresponding to the discharge point for the well. This is typically at or above the land surface, and can be increased to account for additional head loss due to friction in pipes.
liftq0 : float
is the value of lift (total dynamic head) that exceeds the capacity of the pump. If the calculated lift equals or exceeds this value, then the pump is shut off and discharge from the well ceases.
liftqmax : float
is the value of lift (total dynamic head) corresponding to the maximum pumping (discharge) rate for the pump. If the calculated lift is less than or equal to LIFTqmax, then the pump will operate at its design capacity, assumed to equal the userspecified value of Qdes (in dataset 4a). LIFTqmax will be associated with the value of Qdes in the first stress period in which Qdes for the well is less than 0.0.
hwtol : float
is a minimum absolute value of change in the computed water level in the well allowed between successive iterations; if the value of hWELL changes from one iteration to the next by a value smaller than this tolerance, then the value of discharge computed from the head capacity curves will be locked for the remainder of that time step. It is recommended that HWtol be set equal to a value approximately one or two orders of magnitude larger than the value of HCLOSE, but if the solution fails to converge, then this may have to be adjusted.
liftn : float
is a value of lift (total dynamic head) that corresponds to a known value of discharge (Qn) for the given pump, specified as the second value in this line.
qn : float
is the value of discharge corresponding to the height of lift (total dynamic head) specified previously on this line. Sign (positive or negative) is ignored.
mnwpackage : ModflowMnw2 instance
package that mnw is attached to

check
(f=None, verbose=True, level=1)¶ Check mnw object for common errors.
Parameters: f : str or file handle
String defining file name or file handle for summary file of check method output. If a string is passed a file handle is created. If f is None, check method does not write results to a summary file. (default is None)
verbose : bool
Boolean flag used to determine if check method results are written to the screen
level : int
Check method analysis level. If level=0, summary checks are performed. If level=1, full checks are performed.
Returns: chk : flopy.utils.check object

static
get_item2_names
(mnw2obj=None, node_data=None)¶ Determine which variables are being used.
Returns: names : list of str
List of names (same as variables in MNW2 Package input instructions) of columns to assign (upon load) or retain (upon write) in reach_data array.

make_node_data
()¶ Makes the node data array from variables entered individually.

class
flopy.modflow.mfmnw2.
ModflowMnw2
(model, mnwmax=0, nodtot=None, ipakcb=0, mnwprnt=0, aux=[], node_data=None, mnw=None, stress_period_data=None, itmp=[], extension='mnw2', unitnumber=None, filenames=None, gwt=False)¶ MultiNode Well 2 Package Class
Parameters: model : model object
The model object (of type :class:’flopy.modflow.mf.Modflow’) to which this package will be added.
mnwmax : int
The absolute value of MNWMAX is the maximum number of multinode wells (MNW) to be simulated. If MNWMAX is a negative number, NODTOT is read.
nodtot : int
Maximum number of nodes. The code automatically estimates the maximum number of nodes (NODTOT) as required for allocation of arrays. However, if a large number of horizontal wells are being simulated, or possibly for other reasons, this default estimate proves to be inadequate, a new input option has been added to allow the user to directly specify a value for NODTOT. If this is a desired option, then it can be implemented by specifying a negative value for “MNWMAX”–the first value listed in Record 1 (Line 1) of the MNW2 input data file. If this is done, then the code will assume that the very next value on that line will be the desired value of “NODTOT”. The model will then reset “MNWMAX” to its absolute value. The value of “ipakcb” will become the third value on that line, etc.
ipakcb : int
 is a flag and a unit number:
 if ipakcb > 0, then it is the unit number to which MNW cellbycell flow terms
will be recorded whenever cellbycell budget data are written to a file (as determined by the outputcontrol options of MODFLOW).
if ipakcb = 0, then MNW cellbycell flow terms will not be printed or recorded. if ipakcb < 0, then well injection or withdrawal rates and water levels in the well
and its multiple cells will be printed in the main MODFLOW listing (output) file whenever cellbycell budget data are written to a file (as determined by the output control options of MODFLOW).
mnwprnt : integer
Flag controlling the level of detail of information about multinode wells to be written to the main MODFLOW listing (output) file. If MNWPRNT = 0, then only basic well information will be printed in the main MODFLOW output file; increasing the value of MNWPRNT yields more information, up to a maximum level of detail corresponding with MNWPRNT = 2. (default is 0)
aux : list of strings
(listed as “OPTION” in MNW2 input instructions) is an optional list of character values in the style of “AUXILIARY abc” or “AUX abc” where “abc” is the name of an auxiliary parameter to be read for each multinode well as part of dataset 4a. Up to 20 parameters can be specified, each of which must be preceded by “AUXILIARY” or “AUX.” These parameters will not be used by the MNW2 Package, but they will be available for use by other packages. (default is None)
node_data : numpy record array
master table describing multinode wells in package. Same format as node_data tables for each Mnw object. See Mnw class documentation for more information.
mnw : list or dict of Mnw objects
Can be supplied instead of node_data and stress_period_data tables (in which case the tables are constructed from the Mnw objects). Otherwise the a dict of Mnw objects (keyed by wellid) is constructed from the tables.
stress_period_data : dict of numpy record arrays
master dictionary of record arrays (keyed by stress period) containing transient input for multinode wells. Format is the same as stress period data for individual Mnw objects, except the ‘per’ column is replaced by ‘wellid’ (containing wellid for each MNW). See Mnw class documentation for more information.
itmp : list of ints
is an integer value for reusing or reading multinode well data; it can change each stress period. ITMP must be >= 0 for the first stress period of a simulation. if ITMP > 0, then ITMP is the total number of active multinode wells simulated during the stress period,
and only wells listed in dataset 4a will be active during the stress period. Characteristics of each well are defined in datasets 2 and 4.
if ITMP = 0, then no multinode wells are active for the stress period and the following dataset is skipped. if ITMP < 0, then the same number of wells and well information will be reused from the previous stress period and dataset 4 is skipped.
extension : string
Filename extension (default is ‘mnw2’)
unitnumber : int
File unit number (default is None).
filenames : str or list of str
Filenames to use for the package and the output files. If filenames=None the package name will be created using the model name and package extension and the cbc output name will be created using the model name and .cbc extension (for example, modflowtest.cbc), if ipakcbc is a number greater than zero. If a single string is passed the package will be set to the string and cbc output names will be created using the model name and .cbc extension, if ipakcbc is a number greater than zero. To define the names for all package files (input and output) the length of the list of strings should be 2. Default is None.
gwt : boolean
Flag indicating whether GW transport process is active
Examples
>>> import flopy >>> ml = flopy.modflow.Modflow() >>> mnw2 = flopy.modflow.ModflowMnw2(ml, ...)

check
(f=None, verbose=True, level=1)¶ Check mnw2 package data for common errors.
Parameters: f : str or file handle
String defining file name or file handle for summary file of check method output. If a string is passed a file handle is created. If f is None, check method does not write results to a summary file. (default is None)
verbose : bool
Boolean flag used to determine if check method results are written to the screen
level : int
Check method analysis level. If level=0, summary checks are performed. If level=1, full checks are performed.
Returns: None
Examples
>>> import flopy >>> m = flopy.modflow.Modflow.load('model.nam') >>> m.mnw2.check()

get_allnode_data
()¶ Get a version of the node_data array that has all MNW2 nodes listed explicitly. For example, MNWs with open intervals encompassing multiple layers would have a row entry for each layer. Ztop and zbotm values indicate the top and bottom elevations of the node (these are the same as the layer top and bottom if the node fully penetrates that layer).
Returns: allnode_data : np.recarray
Numpy record array of same form as node_data, except each row represents only one node.

static
get_empty_node_data
(maxnodes=0, aux_names=None, structured=True, default_value=0)¶ get an empty recarray that correponds to dtype
Parameters: maxnodes : int
Total number of nodes to be simulated

make_node_data
(mnwobjs)¶ Make node_data rec array from Mnw objects

make_stress_period_data
(mnwobjs)¶ make stress_period_data rec array from Mnw objects

plot
(**kwargs)¶ Plot 2D, 3D, transient 2D, and stress period list (MfList) package input data
Parameters: **kwargs : dict
 filename_base : str
Base file name that will be used to automatically generate file names for output image files. Plots will be exported as image files if file_name_base is not None. (default is None)
 file_extension : str
Valid matplotlib.pyplot file extension for savefig(). Only used if filename_base is not None. (default is ‘png’)
 mflay : int
MODFLOW zerobased layer number to return. If None, then all all layers will be included. (default is None)
 kper : int
MODFLOW zerobased stress period number to return. (default is zero)
 key : str
MfList dictionary key. (default is None)
Returns: axes : list
Empty list is returned if filename_base is not None. Otherwise a list of matplotlib.pyplot.axis are returned.
Examples
>>> import flopy >>> ml = flopy.modflow.Modflow.load('test.nam') >>> ml.dis.plot()

to_shapefile
(filename, **kwargs)¶ Export 2D, 3D, and transient 2D model data to shapefile (polygons). Adds an attribute for each layer in each data array
Parameters: filename : str
Shapefile name to write
Returns: None
Examples
>>> import flopy >>> ml = flopy.modflow.Modflow.load('test.nam') >>> ml.lpf.to_shapefile('test_hk.shp')

write_file
(filename=None, float_format=' {:15.7E}', use_tables=True)¶ Write the package file.
Returns: None