WEL: Well Package Pane

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The WEL: Well package pane is on the MODFLOW Features tab of the Object Properties dialog box.

The data that can be specified for the Well package are the Starting time, Ending time, and Pumping rate. The Pumping rate is the volumetric recharge rate. A positive value indicates recharge and a negative value indicates discharge (pumping).

Starting time and Ending time are explained in the help for the MODFLOW Features tab.

If parameters are used with an object, a multiplier must be defined for each parameter for the Pumping rate. MODFLOW will multiply the multiplier by the parameter value (specified in the MODFLOW Packages and Programs dialog box) to determine the pumping rate to apply.

In many cases, if a polyline or polygon is used to specify a group of wells, it may be advantageous to specify the pumping rate as a rate per unit length or rate per unit area and then multiply by ObjectIntersectLength or ObjectIntersectArea. Doing so makes it possible to modify the grid without reentering information. If the Pumping rate interpretation is set to Calculated, those functions will be included automatically.

Sometimes it may be desirable to specify the total well flux for an object. One way to do this would be to use a formula of the form (Total Rate)/ObjectArea*ObjectIntersectArea or (Total Rate)/ObjectLength*ObjectIntersectLength. If the Pumping rate interpretation is set to Total per Layer, those functions will be included automatically.

If an object defines a well in the Well package in MODFLOW and the object has more than one section, each section will be used to define a separate set of wells. If two or more sections of the same object occur in the same cell, a single well will be defined for that cell with the total pumping rate being the sum of the pumping rates for each section considered separately.

Time-series interpolation

In MODFLOW 6, time series files can specify the times and values to use for a boundary condition.

When MODFLOW 6 needs data from a time series or time-array series for a time interval representing a time step or subtime step, the series is queried to provide a time-averaged value or array of values for the requested time interval. For each series, the user specifies an interpolation method that determines how the value is assumed to behave between listed times. The interpolation method thus determines how the time averaging is performed. When a time-array series is used, interpolation is performed on an element-by-element basis to generate a 2-D array of interpolated values as needed.

The supported interpolation methods are STEPWISE, LINEAR, and LINEAREND. When the STEPWISE interpolation method is used, the value is assumed to remain constant at the value specified in one time-series record until the time listed in the subsequent record, when the value changes abruptly to the new value. In the LINEAR interpolation method, the value is assumed to change linearly between times listed in sequential records. LINEAREND is like LINEAR, except that instead of using the average value over a time step, the value at the end of a time step is used.

ModelMuse uses time-series interpolation when parameters are used. The parameter value becomes the SFAC (scale factor) in the time-series file.

ModelMuse sets the interpolation method to STEPWISE for all boundary conditions in which it is used except for the CHD package in which it is set to LINEAREND.

ModelMuse does not currently support time-series interpolation because it slows down MODFLOW to much as implemented in ModelMuse. Support for time-series interpolation may be supported in a future version of ModelMuse but in a different form.