Groundwater (Ground Water) Pumping Well Data Files
In many cases, it is necessary to import well data to a MODFLOW/MT3D Local Source/Sink coverage in the Map module. When dealing with sites that have several hundred (if not thousands) of wells, creating the wells one at a time is too time-consuming. One option for importing well data is to use shapefiles. However, it may not be convenient to convert the well data to the shapefile format, and shapefiles only support steady state data. The pumping well data file formats can be used to import well data quickly and easily. This approach supports both steady state and transient pumping data.
The well data are imported using two ASCII files. The first file includes the well locations and the screens. If the pumping rates are steady state it also includes the pumping rate. The second file is only used for cases with transient pumping rates. This file includes the transient Q's for some or all of the wells imported using the first file.
Well Data File
The first of the two files is the well data file. The format of this file is as follows:
"name" "x" "y" "z" "depth" "scrlen" "Q"
"well 1" 1237.5 8432.2 625.0 51.4 6.0 -120.5
"well 2" 1345.2 7890.4 621.8 60.7 5.4 -100.3
"well 3" 1478.2 6783.1 615.4 110 10.0 -300.5
&ldots;
The name column lists the name of the well. Point objects in the Map module will now support a name attribute. The name column is optional. If it's missing, GMS assigns the first well a name of "1," the second well a name of "2," etc.
The x and y columns are mandatory. The z, depth, and scrlen columns are optional. These columns serve to define the elevation of the ground surface (this value is assigned as the elevation of the well point), the depth to the top of the screened interval, and the length of the screened interval. GMS computes the top and bottom screen elevations from the given depth and screen length. If these columns are present, the "Partition Q among layers intersecting screen" option is toggled on for the well. If the columns are missing, the "Assign to specified layer" option is used and the wells are assigned to layer 1. The Q column is also optional. The Q column defines a steady state (or constant) pumping rate. If the Pumping Data file is subsequently read in, this Q value may be overwritten for some or all of the wells. If this column is missing, GMS assigns Q=0 to all of the wells (steady state).
The well data file should have the extension *.wdf. It can be imported either through the Import command in the File menu, or through the Import button in the Coverages dialog. In either case, if the current coverage is a MODFLOW source/sink coverage or a FEMWATER coverage, the points are added to the existing coverage. Otherwise the import is aborted.
Pumping Data File
The pumping data file should be imported after the well data file. It is used to import transient pumping data. The format is as follows:
"name" "date" "time" "Q"
"well 1"12/3/1999 18:00:00 625.0
"well 1" 1/30/2000 7:38:25 0
"well 1" 3/27/2000 18:00:00 200.0
"well 2" 12/3/1999 18:00:00 0
"well 2" 12/5/1999 14:48:32 100.0
&ldots;
The name column must be included. This tells GMS how to link the transient pumping data to the wells in the map module. The first time an entry is found for a particular well, if the well is steady state it is changed to transient and a pumping rate time series is created for the well. Each time a subsequent line is read with the same well name, GMS adds a point to the time series. The dates use the MM/DD/YYYY format.
By default, GMS treats all well data as a step function. The date/time shown is analogous to a stress period. When a time series curve is created in GMS, extra points are added to the curve at the end of each period to ensure that the data are treated as a step function.
This file should have the extension *.wpf. The file is imported through the Import command in the File menu or through the Import button in the Coverages dialog. When the file is imported, the active coverage must be a source/sink coverage.
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