Basic Tab

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The Basic tab on the MNW2 pane contains controls relating to the various options that may be specified for the well.

WELLID Each well must have a unique well identification. It is used to identify the well in output files and to generate the name of output files in the Multi-Node Well Information package. Only ASCII characters are allowed in WELLID.

LOSSTYPE The Multi-Node well package provides several ways to calculate the well loss. The controls that are enabled on the Loss Controls tab depend on which LOSSTYPE is selected.

•None This option is only valid for wells at a single cell. The Loss Controls tab will not be visible. Constraints can still be applied to the well which makes it different from a well specified in the WEL package.

•Thiem This option uses the Thiem equation which computes the well loss based on the well radius. There is a linear relationship between the pumping rate and the well loss.

•Skin This option uses an equation in which the well loss is based on the well radius, the radius of the skin around the well and the hydraulic conductivity of the skin. There is a linear relationship between the pumping rate and the well loss.

•General This option allows the user to specify a nonlinear relationship between the pumping rate and well loss. head loss is defined with coefficients A, B, and C and power exponent P (hWELL = hn + AQn + BQn + CQn P). 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).

•Specify cell to well conductance This option allows the user to specify a constant value of the cell to well conductance. 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.

Specify pump (PUMPLOC) If this checkbox is checked, the user will specify the location of the pump using either a pump elevation zpump in vertical wells or as a location in wells that are not vertical.

Pump elevation (zpump) The pump elevation is used to specify the location of the pump in a vertical well.

Pump location method If the user is specifying a pump location and the well is not vertical, the user must specify the pump location. This can be done in one of three ways:

•The Cell can be specified directly.

•An X, Y, Z location can be specified. ModelMuse will use the location to determine the proper cell for the pump.

•A point object can be used. ModelMuse will use the location of the point object to determine the proper cell for the pump.

A different set of controls will appear depending on which method is selected.

Constrain pumping (Qlimit) If this checkbox is checked, the pumping rate can be constrained. The constraints themselves are specified on the Pumping Rate tab.

Correct for partial penetration (PPFLAG) If this checkbox is checked, MODFLOW will make corrections for partial penetration. In vertical wells, the fraction of partial penetration will be determined automatically from the location of the well screen. In wells that are not vertical, the user must define a formula for the partial penetration.

Partial penetration fraction (PP) If a correction for partial penetration well be made in a nonvertical well, the partial penetration fraction is a formula that will be evaluated at each cell that makes up the multi-node well to obtain the correct partial penetration for that cell. In vertical wells, the partial penetration fraction is determined automatically so no formula needs to be supplied.

Adjust discharge for changes in lift (PUMPCAP) If this checkbox is checked, the pumping rate will be adjusted for changes in lift over time. The additional parameters needed to adjust the lift are specified on the Discharge Adjustment and Pumping Rate tabs.

Save well fluxes and head If this checkbox is checked, the flux into and out of the well, the net flux, the cumulative flux and the head in the well will be printed in each time step. The name of the file will, in part, be based on the WELLID.

Save flows between each well node and the aquifer to a separate file (QNDflag) If this checkbox is checked, MODFLOW will create a separate output file for this well in which the flow between each well node and the aquifer will be printed in each time step. The name of the file will, in part, be based on the WELLID.

Save intraborehole flows to a separate file (QBHflag) If this checkbox is checked, MODFLOW will create a separate output file for this well in which the flow among the well node will be printed in each time step. The name of the file will, in part, be based on the WELLID.