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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 Appendix 1—Data Input Instructions for MultiNode Well (MNW2) Package 47 automatically by MNW2.
PUMPLOC 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 multinode 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 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 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 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. Note 3: Discharge is reduced under PUMPCAP independently from a reduction related to constraints (and Qlimit). If both are
applied to the same well, then the most restrictive condition from the two criteria will take precedence. PUMPCAP is only
applied for withdrawal wells (that is, if the specified pumping rate (Qdes in dataset 4a) is negative in sign). If LOSSTYPE ≠ NONE:
2c. Data:
{Rw Rskin Kskin B C P CWC}
Include the appropriate coefficients in 2c, as consistent with the specified LOSSTYPE defined in 2b, as summarized
also in table A1–1.
• if LOSSTYPE = THIEM, then specify Rw (the radius of the well).
• if LOSSTYPE = SKIN, then specify Rw, Rskin (the radius to the outer limit of the skin), and 48 Revised MultiNode Well (MNW2) Package for MODFLOW GroundWater Flow Model Kskin (the hydraulic conductivity of the skin).
• if LOSSTYPE = GENERAL, then specify Rw, B, C, and P, where the last three parameters are
coefficients in the wellloss equation (equation 2). (See notes and suggestions for GENERAL
option under 2b above.)
• if LOSSTYPE = SPECIFYcwc, then specify CWC (the celltowell conductance; see equation 15).
Note 4: Any of the parameters in dataset 2c can be assumed to be constant for the entire length of the open interval of the well
(in which case appropriate values are simply specified above), or it can be assumed that...
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 Winter '14

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