7.0 Model Input Data¶
This chapter describes generating inputs for a MINEDW model using the user interface menus and tool buttons. MINEDW saves the model files and results as a project file format (.PRJ) from which ASCII input files can be generated for the calculation portion of the program. From these files, users can easily restore a saved modeling project and restart the model simulation from any selected time.
7.1 Project Definition¶
The first step to create a new model is to define the project properties. This section describes the project properties, including simulation parameters, units, type of simulation, solver types, and file output names.
7.1.1 Project Properties¶
Project properties are defined by selecting “Project Properties” from the “Project” drop-down menu on the Main Menu banner at the top of the window. Select “Project Properties,” and the “Project Properties” dialog box shown in Figure 7.1 appears. The required information for project properties is described below.
- Project Name:
The user-defined name of the project.
- Output File Name:
The prefix assigned to all MINEDW-created data-set files (e.g., the model file would be labeled “TR_model.dat” when “TR_” is the output file name).
Length units used in the model (meters and feet are the supported units in MINEDW).
- Type of Simulation:
The means by which to select whether the model is a steady-state or transient-state simulation. In steady-state simulations, it is good practice to make sure that the storage changes are smaller than 1.0 x 10-10 cubic meters per day (m:sup:3/day) at the end of the model simulation. This information can be found in the budget and output files (.BUD and .OUT) that are created in the simulation directory. For steady-state simulations, only the first time step defined in the “Time Steps” item in the “Project” drop-down menu on the Main Menu banner is used and, starting from the second time step, the time-step length is multiplied by a factor of 1.2. For transient simulations, the time-step multiplication factor is 1, and the time steps defined in the “Time Steps” dialog box are used. The “Time Steps” item is discussed in Section 7.1.2.
- Maximum Outer Iterations:
The maximum number of outer iterations (an even number generally less than 10) that are to be used to precondition the matrices of equations prior to solving. The appropriate number of maximum outer iterations depends on the solver that is used and the model that is being run. Starting with a smaller number of maximum outer iterations and increasing the iteration value as necessary (review the .BUD or .OUT files for percent residuals) is recommended to ensure the fastest solution time.
Option for the solver type to be used in the model simulation. There are two solver options available in MINEDW: PCG (Preconditioned Conjugate Gradient) and SAMG (Algebraic Multigrid Methods for Systems) (Fraunhofer SCAI 2013).
- Outer Iteration Closure Criterion:
The head closing criteria for outer iterations. Determination of the iteration value depends on the scale of the model being simulated. It generally should be less than 1 meter (m) or 3 feet (ft). The value should be defined based on computational time, accuracy, and mass balance.
- Maximum Inner Iterations:
Maximum number of inner iterations to solve the matrices of equations. This value generally is greater than 1,000, depending on the value of the inner iteration closure criterion. Inner iterations may often be set to a large value without compromising model run time because the solvers use the minimum number of iterations necessary to meet the closure criteria.
- Inner Iteration Closure Criterion:
The closure criterion for the inner iterations. This value is generally less than 1 x 10-10. The smaller the inner closure criterion is, the greater the computational accuracy of the results and the longer the computational time.
- Output Time Step Frequency to PLB File:
The time-step intervals at which MINEDW saves the simulated heads to the output file with a .PLB extension. The default value is 1.
7.1.2 Time Steps¶
The time steps are defined using the “Time Steps” item in the “Project” drop-down menu on the Main Menu banner. During the model setup, if the user selects “Steady State” in the “Project Properties” dialog box, then the “Setup Time Step” dialog box appears as shown in Figure 7.2 when “Time Steps” is selected from the “Project” drop-down menu. If the user selects “Transient” for the model run, then the dialog box shown in Figure 7.3 appears. For a steady-state model, the “Start Date/Time,” “Maximum # of Time Steps,” and “Initial Time Step Length” are the only inputs that need to be defined. The “# of Time steps for this simulation” defines the number of time steps to use for a particular model run, but this parameter is typically the same value as “Maximum # of Time Steps” for steady-state models.
There are three different options for defining time steps for a transient simulation: 1) “Constant,” 2) “Month,” or 3) “Varied.” If the “Varied” option is selected, then the data can be imported from an ASCII data file (the format for the ASCII file is one column that contains the time-step number and another column that contains the number of days for each time step; the input time-step file created by MINEDW is in this format). The time steps and the corresponding dates are shown on the right-hand side of the window (Figure 7.3). The maximum number of time steps can be defined from the same window (Figure 7.3). The “Maximum # of Time Steps” setting covers all of the time steps for different simulations for a project.
Under the simulation time-step section (Figure 7.3), the number of time steps to simulate for a simulation can be set. Using the simulation time-step slider or entry, the user can specify the number of time steps to simulate by choosing either a complete model simulation or an abbreviated model simulation. An abbreviated model simulation will run for the number of specified time steps.
In the simulation start time drop-down box, a model can be restarted from a specified time step by selecting the time step at which the simulation will begin. The simulated head output file (.PLB) must be read before selecting the restart time step; otherwise, the only available option is the first time step. Reading in an output file in MINEDW is described in section 9.1. A model simulation should not be restarted during any part of pit-lake filling.
7.2 Model Geometry¶
While the horizontal geometry of the model domain is defined in the mesh generator, the 3-D layering within the model is defined within the MINEDW GUI using the “Mesh” menu. The following sections describe the functions in the “Mesh” menu.
7.2.1 Generating the Mesh¶
The finite-element mesh defines the geometry to simulate a groundwater system. The MINEDW finite-element mesh consists of a solid configuration of tetrahedrons. Tetrahedrons are difficult solids to use; therefore, the actual mesh is assembled from prismatic elements that are triangular in plan view. The prisms are oriented spatially with sub-horizontal triangular faces and sub-vertical quadrilateral faces. Three tetrahedrons then are automatically fitted into each prismatic element.
To allow flexibility in the construction of 3-D meshes, the MINEDW program accepts prismatic elements that have edges with a height of zero. A prismatic element with one zero-height edge contains two tetrahedrons and an element with two zero-height edges. These special elements can be used to represent geologic features that taper to a thickness of zero or to add vertical refinement in areas of particular interest. Without these special elements, a vertical zone of fine vertical discretization can be terminated only by carrying it to the edge of the model domain.
Generating a MINEDW mesh involves performing the following steps:
Generate a one-model-layer mesh that incorporates the hydrogeologic features in plan view using Rhinoceros 3D and Grasshopper (as described in Chapter 5) or another mesh generator.
Add the ground-surface topography to the main model layer.
Add main model layers according to the stratigraphy, geologic information, or other data.
If needed, add additional vertical model discretization using pinch-outs.
7.2.2 Adding Main Model Layers¶
After importing the mesh generated by Rhinoceros 3D and Grasshopper (Chapter 5), main layers can be added by selecting “Define Main Layer” from the “Mesh” drop-down menu found on the Main Menu banner. A main layer is defined as a layer that extends through the entire model domain. When “Main Layer” is selected, the dialog box shown in Figure 7.4 appears.
To add a new main layer to the model, first select a main layer, then click “Insert.” The new main layer will appear above the selected main layer. The “Method” option will be “Constant,” and the “Value” field will be blank. Select the desired method from the drop-down box in the “Method” field if needed, and then enter the appropriate value in the “Value” field. Click “OK” to add the main layer with the desired elevation or thickness. Note: if the “Average” method is selected, then no value is needed in the “Value” field. The new main layer is placed above the originally selected main layer. An example of the information required for main layers is described below.
The method of defining the elevation of the main layers in Figure 7.4 includes five options, as shown in Figure 7.5, below.
The five options available for main layer creation are the following:
- No Change:
This option retains the existing elevation for the selected main layer.
This option assigns a constant-elevation value.
This option assigns an average elevation of two layers to the newly created main layer or layers. This option is not available for the top and bottom main layers.
This option assigns the elevation by using the defined thickness from the main layer below. This option is not available when adding the bottom layer of the model.
This option assigns the elevation by using the defined depth from the main layer above. This option is not available when defining the elevation of the top layer of the model.
The following are examples for inserting several main model layers into MINEDW:
Constant: Adding a main layer using the “Constant” method will add a nodal layer at the elevation specified in the “Value” field. A nodal layer (creating two new element layers) can be added anywhere using this method, but care must be taken to ensure that the new layer falls between the nodes of the upper and lower node layers.
Average: To add a main layer with an average thickness (Figure 7.6), select a layer and click “Insert.” MINEDW will insert a nodal layer above the selected layer. Select “Average” from the “Method” drop-down box and click “OK.” MINEDW adds a new nodal layer (as shown within the red box) between the top and bottom nodal layers, forming two element layers. Node elevations for this layer are calculated as the average of the top nodal layer and the bottom nodal layer.
Thickness: The “Thickness” option will create a nodal layer (shown within the red box) that is offset by a user-specified value from the nodal layer immediately below, as seen in Figure 7.7. This creates an element layer with elements of uniform thickness. Figure 7.7 displays a nodal layer that has a constant elevation and an element layer of uniform thickness; however, it is possible to create a nodal layer that does not have a constant elevation but that forms an element layer of uniform thickness. This occurs when the reference nodal layer does not have a constant elevation.
Depth: The “Depth” method is similar to the “Thickness” method, with the exception that the upper nodal layer (rather than the lower nodal layer) is used as the reference layer to calculate the location of the nodal layer that is being added. In contrast to the nodal layer with uniform elevation, shown in Figure 7.7, the nodal layer in Figure 7.8 does not have a uniform elevation because the upper nodal layer that was used as the reference to calculate the location of the new nodal layer did not have a uniform elevation.
7.2.3 Using Topography Data¶
The following describes how to add topographic information to the first model layer, but the same steps can be repeated to apply topography to any model layer.
To incorporate topography in a model, select the “List” tab in the “Control Panel” Pane on the right-hand side of the MINEDW Main Menu. Expand the “Node” item by double-clicking “Node” or clicking on the small triangle next to “Node.” Next, double-click “3D Contour,” as shown in Figure 7.9. The mesh will be displayed in the View Pane.
Click the “Select” tool on the toolbar. From the “Control Panel” Pane on the right-hand side of the MINEDW window, select the “Attributes” tab. Make sure that “Layer 1” is selected and “Elevation” (in the “Color By” drop-down box) is selected, as shown in Figure 7.10.
In the MINEDW View Pane, use the cursor to click and drag a box around the whole domain to select all of the nodes in Layer 1. Press the [Enter] key to open the dialog box shown in Figure 7.11. Click the button next to “Interpolate From File,” and the “Open Data File” dialog box appears. Select a file with XYZ data (this file is formatted as columns of x, y, and z data) that contains the topographic information that will be added to the model, and click “Open.” The “Grid” dialog box shown in Figure 7.12 appears. Define the interpolation method (“Inverse Distance” or “Kriging”) and the required parameters, and then click “OK.” MINEDW assigns the topographic information contained in the data file to the top layer of the model using the interpolation method. This method can be used to assign elevation data to all of the nodal layers in the model. To assign elevation data to other nodal layers, simply select the desired layer on the “Attributes” tab of the “3-D Contour” plot item and repeat the steps described above.
To view the ground-surface elevation contours, add an “Isoline” plot item and select “Elevation” as the “Color By” attribute. The counter intervals may be manipulated by using the options under the “Contour” attribute of the “Isoline” plot item. Click on the “Attributes” tab in the “Control Panel” Pane, and then click on the small triangle next to “Contour.” Deselect the “Auto” box next to “Interval” and replace the current value with a different value, then press the [Enter] key, and elevation contours appear. An example of ground-surface elevation contours is shown in Figure 7.13.
7.2.4 Importing Node Elevations¶
Node elevations can be assigned to all of the nodes in the model domain by importing a node-elevation file. Node elevations are written to a file called “node.fem” by the MINEDW GUI. This file is a simple text file that can easily be created using another MINEDW model or other software. The file contains five columns of data: 1) node number, 2) x location of node, 3) y location of node, 4) z location (or elevation) of node, and 5) node layer.
To import and assign node elevations for the entire domain, select “Import Elevations From Node File” found under the “Project” drop-down menu on the Main Menu banner. Use the “Import Node File” dialog box that opens to navigate to the location of the node elevation file. Select it and click “Open” to complete the assignment. The default file type for node elevations in MINEDW is the .FEM file type. MINEDW creates three files with the .FEM extension, but only the “node.fem” file can be used to import node elevations.
7.2.5 Defining a Pinch-Out¶
MINEDW provides the option of adding areas of increased vertical discretization. The enhanced vertical discretization is referred to as a pinch-out because layers terminate in areas where increased vertical discretization is not needed. To define the pinch-out types, select “Mesh” from the Main Menu banner and then select “Define Pinch-Out.” The “Define Pinch-Outs” dialog box appears (Figure 7.14).
In MINEDW, various pinch-out configurations can be defined and simulated. Each configuration is defined as one type of pinch-out. Based on their modeling needs, the user can define as many pinch-out types as necessary. Each type can contain pinch-outs of as many layers as needed.
Figure 7.15 illustrates the working principle of the pinch-out method. For example, a model has four regional layers that are each represented (sequentially, Layer 1 to Layer 4, from top to bottom) by a row of black squares in Figure 7.15. The left column shows the number of pinch-out layers (shown in blue) allowed for each model layer. For illustration purposes, three different combinations are represented, which are each defined as a different type in Figure 7.15. Type 1 consists of three pinch-outs on model Layer 2 (represented as red lines). Type 2 consists of three pinch-outs on model Layer 2 (represented as red lines) and two pinch-outs on model Layer 3 (represented as a green line). Type 3 consists of two pinch-outs on model Layer 3 (represented as a green line). Only one number of pinch-outs can be defined for each model layer. For example, in Figure 7.15, model Layer 2 cannot have three pinch-outs in one area and two pinch-outs in another area. In this example, there will be exactly three pinch-outs anywhere pinch-outs are added to model Layer 2.
To define pinch-outs, click the “Add” button on the right side of the “Define Pinch-Outs” dialog box. Type the number of pinch-outs for each layer in the column labeled “# of Sublayers,” and enable the pinch-out for the related layer by checking the box. Figure 7.16 shows how to define pinch-outs to achieve the schematic shown in Figure 7.15. When the pinch-out types are completely defined, click “OK.”
In this example, “Type 1” will have three pinch-outs in Layer 2, while “Type 2” will have the same three pinch-outs in Layer 2 as well as two pinch-outs in Layer 3. “Type 3” pinch-outs will have only two pinch-outs in Layer 3. To assign pinch-outs to an area, select the “List” tab in the “Control Panel” Pane. Expand the “Element” item and double-click “Pinch-Out.” From the main window, click the “Select” tool on the Main Menu banner. Then use the “Select with Polygon” tool to select the area where pinch-outs are to be added. Figure 7.17 shows an example of the nodes being selected for adding pinch-outs.
Press the [Enter] key, and the “Select Pinch-Out Type” dialog box opens (Figure 7.18). Select the type of pinch-out to add to this location from the drop-down list and click “OK.”
Figure 7.19 shows the pinch-outs described in Figures 7.15 and 7.16 in the View Pane.
7.2.6 Modifying the Mesh¶
Using the “Modify Mesh” function in MINEDW, the user can extend the model domain and refine the mesh after it is created or at any time during the model setup. The mesh can be refined in a user-specified location or extended to cover a larger area.
To refine the mesh, click “Modify Mesh” from the “Mesh” drop-down menu found on the Main Menu banner. This will open an “Open BLN File” dialog box (Figure 7.20). Select a .BLN file that defines an area inside the current model domain to refine and click “Open.”
The “Refine Mesh” dialog box shown in Figure 7.21 appears. If the .BLN file defines an area unconnected to the current model mesh, the operation will yield a warning message. Enter the mesh density and click “OK.”
MINEDW can also extend the mesh after it has been created. Click “Modify Mesh” from the “Mesh” drop-down menu found on the Main Menu banner. The area to be extended is defined by a .BLN file created in Surfer™ or in a text editor. When “Modify Mesh” is selected from the “Mesh” drop-down menu, the “Open BLN File” dialog box shown in Figure 7.20 appears. Select the .BLN file defining the area to be extended. Click “Open.” The “Refine Mesh” dialog box shown in Figure 7.21 appears. Enter the mesh density and click “OK.” Figure 7.23 shows the mesh before and after the mesh extension.
7.3 Zone Properties – Hydraulic Parameters¶
This section describes the zone properties (hydraulic parameters) that are assigned to the model. The term “zone” is a synonym for the type of aquifer material that composes the element; each element is assigned a zone type. Consequently, the zone definitions change only when the user moves a geologic boundary or defines a new geologic material (zone). Zone definitions include the hydraulic conductivity, specific storage, specific yield, and the principal directions of the hydraulic conductivity field, which can be specified in the x, y, and z directions.
The hydraulic parameters that characterize each zone are defined by selecting “Project” and then “Zone Properties” (Figure 7.24).
The information provided in the “Zone Properties” dialog box is described below.
Name of the geologic unit. The name is used in the display and output files.
Hydraulic conductivity in x direction (meters per day [m/day] or feet per day [ft/day]).
Hydraulic conductivity in y direction (m/day or ft/day).
Hydraulic conductivity in z direction (m/day or ft/day).
Specific storage (m-1 or ft-1).
Specific yield (-).
- Angle1 (Φ):
3-D anisotropy, the angle of rotation around the z-axis in degrees.
- Angle2 (θ):
3-D anisotropy, the angle of rotation around the y-axis in degrees.
- Angle3 (ψ):
3-D anisotropy, the angle of rotation around the x-axis in degrees.
The angles (“Angle1,” “Angle2,” and “Angle3”) used to define the hydraulic conductivity tensor are illustrated in Figure 7.25. As described above, the direction of rotation is around the z-axis, y-axis, and finally the x-axis.
After defining the “Zone Properties,” see the explanation in Section 6.1 on how to select elements and assign them with the created hydrogeological zones.
7.3.1 Zone Distributions (para.fem)¶
As described in Section 6.1, hydraulic zone properties can be assigned using the “Select” tool and the “Select Geology Zone” dialog box or a 3-D .DXF. Another method is to import a “para.fem” file, which contains the hydraulic zone definition for each element in the model domain. This file consists of three columns of data: 1) the element number, 2) the hydraulic zone number, and 3) the element layer number. This file can be created using another MINEDW model with the same domain or other software.
To import a “para.fem” file and change the distribution of hydraulic parameters of a model, click on “Import Zones from Parameter File” under the “Project” drop-down menu on the Main Menu banner. Using the “Import Zone File” dialog box, navigate to the location of the “para.fem” file, select it, and click “Open.” The new hydraulic zone distribution will be assigned to the model domain.
7.3.2 Zone Properties (kfile.dat)¶
New parameter values for hydraulic zones can be imported into MINEDW from the “kfile.dat” file, which can be edited by any text editor. To import a new “kfile.dat,” open the “Zone Properties” dialog box (Figure 7.24). Using the “Import” button, open the “Open Zone Properties File” dialog box. Navigate to the location of the new or updated “kfile.dat,” select it, and click “Open.” The parameter values will be updated in the “Zone Properties” dialog box.
7.4 Boundary Conditions¶
A groundwater flow model requires an appropriate set of boundary conditions to describe the mathematical problem that will be solved. In MINEDW, six types of boundary conditions are available: 1) constant head, 2) variable flux, 3) pumping well, 4) rivers, 5) recharge, and 6) evaporation. Of these six types, constant head, variable flux, pumping wells, and rivers are assigned to nodes, while recharge and evaporation zones are assigned to elements.
To define the boundary conditions, select “BCs” from the Main Menu banner, then choose the appropriate boundary-condition type from the “BCs” drop-down menu (Figure 7.26). Each boundary-condition type requires a different set of parameters, as described below. (Note that the data-input windows have similar features and functionality).
Boundary conditions are assigned using node or element plot items. Use the “Assign Properties for Nodes” dialog box to assign “Constant Head & Drain,” “Variable-Flux,” and “Pumping Well” boundary conditions. The “Assign Properties for Nodes” dialog box shown in Figure 7.27 can be accessed by adding a “2D Contour” or “3D Contour” plot item from the “Control Panel” Pane. Select the desired nodes and then press [Enter] to bring up the dialog box.
Recharge and evaporation boundary conditions can be applied to the model using a “2-D Plane” plot item. To assign recharge or evaporation to the model, access the “Select Recharge Zone” or “Select Evaporation Zone” dialog box, shown in Figures 7.28 and 7.29, respectively, by adding a “2-D Plane” element plot item from the “Control Panel” and then selecting the desired “Color By” attribute, “Recharge,” or “Evaporation.”
Next, select the desired elements using the methods described in Section 6.1, press [Enter], and the “Select Recharge Zone” or “Select Evaporation Zone” dialog box appears. Assigning recharge and evaporation boundary conditions is described in more detail in Sections 7.4.6 and 7.4.7.
All boundary conditions can be applied as time-varying conditions. The implementation of these time-varying conditions is described in Section 7.4.1 below, which is followed by a description of each type of boundary condition available in MINEDW.
7.4.1 Time-Series Data¶
Time-series data can be imported from files or directly defined in the time-series dialog boxes (Figure 7.30) that are available within the different boundary-condition dialog boxes. A time series consists of a user-defined number of data pairs (time, value).
There are three different options in MINEDW for the input of time-series data (Figure 7.31):
The boundary-condition data is constant, regardless of time.
The values are defined for a year and repeated each year for the entire model-simulation time period.
The values are defined over time.
Time-series data can be imported from a text file (Appendix B). The plot on the left-hand side displays the time-series data. For any period during which the pump is turned off, enter “0” for wells that are defined as “Pumping Rate” or “LPE” wells (lowest pumping elevation wells) and “N/A” or “-99999999” for wells that are defined as “Specified Head” wells. Time-series data can also be exported to a .DAT file. After any modifications, make sure to click “Apply” to save the changes.
7.4.2 Constant Head¶
The “Constant Head” option is used to implement specified-head boundary conditions, which can take the following forms:
The constant-head boundary is invariant with time (constant time series).
The constant-head boundary varies with time in accordance with a specified hydrograph, which is input in the form of a table of the hydraulic heads at specified times (varied time series).
The constant-head boundary varies annually in accordance with a specified hydrograph, which is input in the form of a table of the annual hydraulic heads (annual time series).
The boundary condition is simulated as a drainage node. A drainage node is the condition in which water can discharge from—but not into—the groundwater system. This condition can exist if groundwater can discharge to a subsurface drainpipe, to the pit wall, or to underground workings. Time-series data can also be applied to drain nodes and represent the time-varying head (drain level) at the drain node. Ensure that drain levels are not lower than the elevation of the node that the drain is defined on and that drain levels do not exceed the elevation of the node directly above the drain. If this occurs, MINEDW will provide the user with a warning and the drain node will not be simulated properly.
“Constant Head” nodes and “Drain” nodes can be deactivated (turned off) at any time during the simulation by entering the appropriate date and a value of “-99999999” in the time-series window. Entering a value of “0” for either boundary condition will not deactivate the boundary condition, but rather, it will assign the boundary condition a constant head or drain level of 0 m.
When “Constant Head” is selected from the “BCs” drop-down menu, the dialog box in Figure 7.32 appears. The required data for a constant-head boundary condition are described below.
- Enable Nonlinear Flow:
Option to simulate nonlinear groundwater flow at drains and constant heads. If enabled, the user has the option to enable nonlinear flow for every group. If the user chooses to use nonlinear flow, they must define the nonlinear flow ratio. The nonlinear flow ratio is the ratio of Non-Darcian to Darcian flow; a value of 0 indicates the flow is completely Darcian.
- Group Definition:
The “Group Definition” portion of the “Constant-Head Boundary” dialog box allows the user to define groups of constant-head or drain boundary conditions.
Constant-head or drain groups are added by clicking the “Add” button at the top of the dialog box. With the drop-down box (Figure 7.32), next to the “Activate” checkbox select either “Constant Head” or “Drain” to define the type of boundary condition the group will be. Each group added will appear in the “Groups” drop-down list shown in Figure 7.33. The names of each group can be modified as desired, as shown in Figure 7.33. Use the “Delete” button to remove unneeded group names, and check or uncheck the “Active” box to activate or deactivate constant-head and drain groups. If nonlinear flow is to be simulated for the constant-head or drain group, check the box next to “NonLinear Flow” and input a value for “Ratio.”
Constant-head groups allow the user to group constant-head nodes or drain nodes together to calculate the flux for each constant-head group (e.g., a set of sub-horizontal drain holes or a regional constant-head boundary). Output flux with respect to time is calculated for each group and is output in the flow file (.FLW).
- Node #:
The node number where the constant-head boundary condition is defined.
The constant-head group to which a particular node is assigned. Using the drop-down box below “Group Definition,” the user can select any of the constant-head groups.
- Type drop-down list:
This drop-down list is located to the right of the “Group” drop-down list. It is used to specify the type of constant-head node (constant-head or drain node).
Constant-head elevation; if constant, varied, or annual, constant-head elevations can be edited in the time-series data box on the right side of the “Constant-Head Boundary” dialog box.
Leakance factor (square meters per day [m2/day] or square feet per day [ft2/day]). Leakance factors can be “Constant,” “Annual,” or “Varied.” These options are available in the lower time-series data box on the right side of the “Constant-Head Boundary” dialog box.
Once the constant-head groups are defined, constant-head nodes can be assigned in several different ways. First, a “2D Contour” or “3D Contour” plot item can be added and nodes can be selected (as described in Section 6.2) to bring up the “Assign Properties for Nodes” dialog box shown in Figure 7.34. Here, the boundary conditions for the selected nodes can be modified. Once the “Add to Constant-Head Boundary” button is clicked, the user has the option to select the constant-head group from a drop-down menu as well as the layers to which the constant head will be applied, with the top layer being the one selected in the “Plot Item” attributes menu.
Additionally, constant-head nodes can be created in the “Constant-Head Boundary” dialog box (Figure 7.32) in several different ways. First, a “chead.dat” file from a previous model data set can be imported using the “Import” button. Also, constant-head nodes can be defined using a .BLN file and the “Create” button. This function can be used to quickly create sub-horizontal drain holes, which are commonly used in mining operations to minimize pore pressures in the pit wall. To use this function, click “Create,” and a “Select BLN File” window opens. Select the .BLN file representing the sub-horizontal drain hole and click “OK.” Drain nodes will be created at nodes close to the .BLN file. The drain elevation assigned by default to each of the drain nodes will be the node elevation. Finally, constant-head nodes can be created manually by entering the required parameters in the table.
Parameters of the constant-head nodes can be edited by group using the “Group” drop-down box. When the name of each constant-head group is selected, the nodes composing the group appear in the window below the drop-down box. After selecting the desired group, the constant-head nodes composing the group can be selected by clicking in the upper left-hand corner of the table. Once the nodes in the desired group are selected, they may be edited as a group by entering values for “Head” or “Leakance” in the appropriate time-series window.
When a “Constant Head” or “Drain” record is selected, the time-series dialog becomes active. In the time-series dialog, the user is able to import time-series data for constant heads or drain nodes. The three options are 1) “Constant,” 2) “Annual,” and 3) “Varied.” These options are explained in the beginning of this section.
The “Variable-Flux” boundary condition is used to specify variable-flux boundary conditions. The variable-flux boundary is used to simulate a domain of large extent without the need to greatly extend the model domain. The “Variable-Flux” option applies the analytical solution for a semi-infinite aquifer to the boundary of the modeled flow domain. To ensure that the variable-flux boundary conditions are implemented properly, the actual boundary of the model domain should be far enough from any hydraulic stress so that effects from these hydraulic stresses do not reach the variable-flux boundary condition.
To add a variable-flux boundary condition to the model, add a “2D Contour” or “3D Contour” plot item to the View Pane. Next, toggle to the desired node layer using the “Layer” attribute of the “2D Contour” or “3D Contour” plot item. Use the “Select” tool from the toolbar to select the nodes on the edge of the model domain where the variable-flux boundary condition is to be assigned. When the nodes are selected, press the [Enter] key to open the “Assign Properties for Nodes” dialog box. Check the radio button next to “Assign to Variable-Flux Boundary”; this will activate additional options. The additional options are “All nodes in between (counterclockwise) are selected,” which will assign the variable-flux boundary condition to all the perimeter nodes of the model domain between two selected nodes in a counterclockwise direction, and “From Current Layer # To,” which will assign the variable-flux boundary condition from the currently selected layer to the chosen layer. The nodes that have a variable-flux boundary condition assigned can be modified using the “Variable-Flux Boundary” dialog box under the “BCs” drop-down menu found on the Main Menu banner at the top of the screen. The “Variable-Flux Boundary” dialog box is shown in Figure 7.35. The information that can be modified for the variable-flux boundary condition is described below.
- Node #:
The uppermost node number of the variable-flux boundary condition.
- Top Layer:
The uppermost layer number in which the variable-flux boundary condition begins.
- Bottom Layer:
The layer number in which the variable-flux boundary condition ends.
Option to Apply Constant Flux from Steady-State Simulation: Note that this requires a .DRN file from a steady-state simulation. To import the .DRN file, click “Import from DRN File” and navigate to the location of the .DRN file using the “Open Variable Flux File” window.
7.4.4 Pumping Well¶
This option is used to specify values for source/sink terms modeled as pumping wells. When “Pumping Well” is selected from the “BCs” drop-down menu found on the Main Menu banner at the top of the screen, the dialog box shown in Figure 7.36 appears. In MINEDW, there are three options available for pumping wells. Pumping wells can be introduced to the model by defining pumping rates, specified heads, or pumping rates with an LPE (“Pumping Rate,” “Specified Head,” or “Pumping with LPE”).
Pumping wells can be added to the model by importing a previously created “pumpwells.dat” file; the format of this file is discussed in Appendix B. To import the file, simply click on “Import” and, using the “Open Pumping File” window that opens, navigate to the location of the “pumpwells.dat” file, select it, and click “Open.” Note, if there are any existing wells in the “Pumping Well” dialog box, they will be overwritten and replaced with the contents of the “pumpwells.dat” file.
Pumping wells can be created by MINEDW based on x, y, and z data in a .DAT file. To use this function, the file should contain three columns of x, y, and z data corresponding to the locations of the pumps to be created in the model. Click on the “Create” button and, using the “Select DAT file” window that opens, navigate to the directory containing the file with location data for the pumps, select it, and click “Open.” MINEDW will select the finite-element node at the specified x, y, and z locations, or if no node exists at a location, MINEDW will move the closest node to that specified location. The user can then use the “Pumping Well” dialog box to modify the screen intervals, pumping rate, and pumping well type.
Another option for adding pumping wells to the model is to select the nodes where pumping wells are to be simulated using a “2D Contour” or “3D Contour” plot item and the “Select” tool and then choosing “Add to Pumping Wells” in the “Assign Properties for Nodes” dialog box as described in Section 6.2. The user must take care to select the correct node layer in the “3D Contour” plot item where the pumping well is to be simulated. For example, if the user inadvertently uses the top node layer, the pump or sink will be simulated at the top of the model domain and will likely be ineffective at removing groundwater from the system. Also, the user will have to specify the screen intervals, pumping well type, and pumping rates in the “Pumping Well” dialog box after adding pumping wells using this method.
In MINEDW, a “Pumping Rate” well allows the user to specify the exact pumping rates they want to use for a model simulation. This type of pumping well is useful for a model calibration simulation when field-recorded pumping-rate data are available. As mentioned above, using a “Pumping Rate” well may dry out the groundwater system within the vicinity of the pumping well if the pumping rate is too large or the hydraulic conductivity values assigned are too low. MINEDW will print a warning to the “MINEDW.err” file if this occurs during a model simulation, but it is the user’s responsibility to check this file, as MINEDW does not stop running when this occurs.
“Pumping Rate” wells have the option to move to the first wet node if the node where the pump is located becomes dry. This option should be exercised with care, as MINEDW will continue to move the pumping node lower, which may result in the pumping node moving to the bottom of the model domain. A pumping node located at the bottom of the model domain (on a no-flux boundary) is incorrect, as pumping stresses should not propagate to a boundary condition. If the user wishes to use this option, they are advised to check that pumping stresses never intersect other user-defined boundary conditions as the pumping node moves downward. To activate this option, check the box next to “Well (Pumping Rate only) will be moved to first wet node when dry,” and the nodes defined as a “Pumping Rate” well will be moved to the next wet node when the pumping nodes become dry.
“Enable Nonlinear Flow” enables nonlinear flow for pumping wells. If this option is enabled, the “Nonlinear” field will become visible in the “Pumping Well” dialog box. Each well where nonlinear flow is to be simulated will need to be enabled individually. The required information for the “Pumping Well” dialog box is described below.
Name of the pumping well.
- Node #:
Identity of node in the pumping data set.
Switch for the type of pumping well (options available are “Pumping Rate,” “Specified Head,” and “Pumping with LPE”).
- Screen Top:
Elevation of screen top (in meters or feet).
- Screen Bottom:
Elevation of screen bottom (in meters or feet).
Defined as either the LPE or the specified head depending on the type of well defined.
Enables nonlinear for the selected well.
The ratio to use for nonlinear flow.
After selecting a pumping well in the “Pumping Well” dialog box, the time-series menu becomes active, as shown in Figure 7.36. In this menu, the user can import time-series data for each type of pumping. The three options are “Constant,” “Annual,” and “Varied” (as described in Section 7.4.1).
“Specified Head” pumping wells are analogues to drains because they can be used to achieve a specific-head value within the groundwater system surrounding the well by extracting the necessary amount of water. Unlike drains, however, no leakance values need to be defined for “Specified Head” wells. “Specified Head” wells are often used in predictive simulations to evaluate dewatering requirements. When used for this purpose, the objective is to achieve the dewatering needs of the project and quantify the amount of water that will need to be extracted to achieve the dewatering target. After quantifying the dewatering requirements, the physical well can be designed to achieve the simulated pumping rates. However, if a “Specified Head” well is used to simulate an existing well, it would be prudent to ensure that the calculated pumping rates of the simulated well do not exceed the maximum pumping rate of the physical well.
Finally, the “LPE” well, which is typically used in a predictive simulation, is defined by assigning a pumping rate to the well and the LPE. The LPE allows the user to specify the minimum allowable head in a well. If the head within the well is equal to or less than the LPE, the pumping rate will be reduced in order to maintain the LPE until the head exceeds the LPE. If the head exceeds the LPE, then the “LPE” well will pump at the rate defined by the user. This feature allows the user to ensure that a proper water-column height is maintained or that the groundwater system does not become dry due to either high pumping rates or low permeability. If an “LPE” well is used during calibration, the user should compare pumping rates printed in the .FLW file with those that were assigned. If rates in the .FLW file are less than the rates that were assigned, this may indicate that the hydraulic parameters assigned to the model are too low. Conversely, assigning maximum pumping rates to “LPE” wells during predictive simulations allows the user to determine the maximum pumping rates that can be sustained with the assigned hydraulic parameters.
The “River” boundary condition is used to simulate interactions between a routed river and an aquifer. The routed-river function uses Manning’s equation to calculate the flow in an open channel. A given reach of the river is represented by a node and corresponding reach length. Each reach is connected to the next reach by sequencing the nodes from upstream to downstream. River-groundwater system interactions are simulated by comparing the head in the groundwater system to the head in the river over time and by transferring water across the riverbed accordingly. Rivers can be connected to form a river network. External sources of water to rivers are termed “tributaries.”
The physical accuracy of a river’s representation depends upon the number of nodes used to resolve the geometry of the river in plan view and the physical coefficients used to calculate gains and losses to and from the river.
When “River” is selected from the “BCs” drop-down menu on the Main Menu banner at the top of the screen, the dialog box shown in Figure 7.37 appears.
Rivers are defined by clicking the “Add” button at the top of the “River” tab of the “River” dialog box. Unlike boundary conditions such as pumping wells, constant heads, drains, or variable-flux boundaries, rivers cannot be created using any plot items. A river can only be created in the following two ways:
From a “BLN” File: This is done by clicking the “Create” button on the lower right of the “River” tab, which opens the “Select BLN file” dialog box. After selecting the appropriate .BLN file, click “Open” and MINEDW automatically selects the appropriate nodes based on distance from the .BLN defined line. MINEDW then calculates the riverbed elevations and the elevation difference between the upstream and downstream node.
Manually: The user can manually enter node numbers; riverbed elevations can then be automatically generated by MINEDW using the “Follow Topo” button.
For any river, the user has the choice of calculating the slope based off the topography using “Follow Topo,” which is the default setting, or applying a “Constant Slope.” For the “Constant Slope” option for the entire river channel, the “Slope” box will become active and the “Bed Elev.” column of the table will no longer be visible. The slope of all segments of the river will be constant. If the “Constant Slope” option is used, then the “First (Lowest) Node Bed Elevation” is used as a reference to calculate other bed elevations. When using “Constant Slope,” if the river is connected to another river, the elevation of the node that forms the river connection is used as the reference elevation rather than the “First (Lowest) Node” and “Bed Elev.”
For each river, the “Manning Coefficient,” river channel “Width,” “First (Lowest) Node,” “Bed Elev.,” and bed hydraulic conductivity must be defined. The following is an explanation of the required information:
- Manning’s Coefficient:
Empirical coefficient for river depth [TL-1/3].
Coefficient for river width [L].
- First (Lowest) Node:
The node number of the lowest node, which should correspond to the first node forming the river.
- Bed Elev.:
The elevation of the riverbed at the downstream node forming the river [L].
Additionally, for each node composing the river, the following must be defined:
The node number for nodes forming the river.
- Riverbed elevation:
The elevation of the riverbed at the node (optional if “Constant Slope” is used) [L].
- Bed Conductivity:
The riverbed hydraulic conductivity [LT-1].
Option to print simulation results for the node to the output file. At a minimum the results at the end node, or any connected node, will be printed out.
Next, “Tributaries” are entered. “Tributaries” are inflows of water to the river and can be used to simulate inflow from outside the model domain or discharge from an outfall such as a lined channel, pump, etc. inside of the model domain. The flow from a tributary can be “Constant,” “Annual,” or “Varied.” Figure 7.38 shows the “Tributary” tab of the “River” dialog box.
Tributaries are added by clicking the “Add” button at the top of the window and specifying the node at which the inflow occurs. The start date of the inflow and the amount of inflow in m3/day or cubic feet per day (ft3/day) can be specified in the time-series table on the lower right. The graph to the left of the table shows the inflow values over time. A time series may be imported as a .DAT file using the “Import Series” button.
The last tab in the “River” dialog box, shown in Figure 7.39, describes the connections between individual rivers and between rivers and tributaries. The user does not need to specify the connection points but can check here to ensure that the rivers and tributaries are connected correctly. If any changes to the river network have been made or a new river network has been created, clicking the “Refresh” button redefines the connections.
MINEDW can simulate temporal and spatial variation in recharge. Spatial variation in recharge can be added to a MINEDW model by creating any number of recharge zones and applying those zones to the model domain. Time-series precipitation data can be used to add temporal recharge information to each zone. With MINEDW, the user can also create zones with orographically controlled recharge, which may be useful for mountainous regions.
When “Recharge” is selected from the “BCs” drop-down menu on the Main Menu banner at the top of the screen, the dialog box shown in Figure 7.40 appears. To create a recharge zone with only temporal variation in recharge, select the “Temporal” tab and then choose “Constant,” “Annual,” or “Varied” for the type of time-series recharge data that will be defined. Next, define the start date and recharge rate in the box below. Note that if the elevation function for recharge is used, then the values defined in the time-series window will not be precipitation rates but rather will be scaling factors. The elevation function for recharge and scaling factors that can be applied are explained on the following pages. A time-series chart appears in the window to the left, displaying the defined data. Note that the units used in this dialog box are specified in the uppermost portion of the window.
The “Elevation” tab in the “Recharge” dialog box allows the user to create zones of orographically controlled recharge. Using this method, the net recharge to the groundwater system can be calculated as a percentage (0–100%) of the total precipitation that falls in orographically controlled precipitation zones. This method works well for groundwater models that include mountain and valley systems.
Orographically controlled precipitation is calculated using a nonlinear relationship between precipitation and ground-surface elevation. Parameters for the equation below can be estimated by fitting the equation to observed precipitation for a range of elevations. The relationship is defined as follows:
To activate this option, select the “Elevation” tab and check the box next to the elevation-based precipitation equation and define the required parameters in the now active dialog boxes (Figure 7.41). Below the area where the parameters for the elevation-based recharge equation are defined is a window where elevation factors can be defined. These factors can be used to specify the percentage of total precipitation, calculated by the elevation-based precipitation equation above, that will be applied as recharge to the aquifer for a specific elevation band. For example, consider two different elements with average elevations of 800 and 1,500 m and calculated precipitations of 25 and 80 centimeters per year (cm/yr), respectively. Supposing that two elevation factors were defined as displayed in Figure 7.41, then recharge for the first and second elements would be 8.75 and 60 cm/yr, respectively. The following equation shows how these recharge values are calculated.
Recharge calculated using elevation factors:
Temporal factors can also be applied to precipitation calculated via the elevation-based precipitation equation. Temporal factors can be applied in addition to ground-surface elevation factors. To define temporal factors, first activate the elevation-based precipitation equation on the “Elevation” tab, define the necessary parameters, and, if desired, define elevation factors. Next, select the “Temporal” tab and create the temporal factors. Temporal factors are defined similarly to temporally varying recharge, as described at the beginning of Section 7.4.1. The options for temporal factors are “Constant,” “Annual,” and “Varied.” For illustration purposes, suppose that recharge to an aquifer during winter is reduced because precipitation falls as snow and sublimates rather than melting and infiltrating. In order to account for this phenomenon in the model, the user could define temporal factors to reduce recharge during the winter months. Figure 7.42 shows an example of how the user might define these annually repeating temporal factors. For January and February, the recharge to the aquifer is 25% of what is calculated by the elevation-based precipitation equation, whereas for March, April, and May, it is 50% of precipitation. For summer months and into fall, recharge is 100% of precipitation, and, finally, for late fall into early winter, recharge is 75% of calculated precipitation. If elevation factors are also defined, then recharge will first be adjusted by the appropriate elevation factor and then by the temporal factor. The following equations show how recharge is calculated using only temporal factors as well as temporal factors with elevation factors.
Recharge calculated using temporal factors:
Recharge calculated using elevation and temporal factors:
As previously noted, the values defined in the time series section of the “Temporal” tab of the “Recharge” dialog box represent scaling factors if the elevation function is activated. If the elevation function is not used, then these values will be used by the model as precipitation rates.
If the “Recharge will be applied to first wet layer” box is checked, then recharge is applied directly to the first wet layer; otherwise, it is applied to the top layer.
The required information for recharge zones is described below.
Number of recharge zones. Two options are available: constant (recharge is simulated constant over time) and time varied (recharge is simulated variable over time).
Recharge rate (millimeters per day [mm/day] or feet per year [ft/yr]).
To assign the created recharge zones, add a “2-D Plane” plot item to the View Pane and select “Recharge” as the “Color By” option. Click the “Select” tool in the “Tool Bar” and then select the elements where the first recharge zone is to be assigned. Press [Enter] when the selection is complete, and select the appropriate recharge zone in the drop-down list and click “OK” to complete the assignment. Repeat these steps until all the zones have been assigned.
The “Evaporation” boundary condition is used to simulate the discharge of groundwater from a shallow water table due to evapotranspiration from vegetated areas or evaporation from a bare-soil area. In this option, the evapotranspiration rate depends on the local depth to the water table, the extinction depth, the potential evapotranspiration rate, and the size of the evaporation zone. The simulation assumes that discharge is linearly related to the depth from just below the ground surface down to the water table. The linear relation holds until a maximum depth is reached; this is the extinction depth. At the extinction depth, evapotranspiration (or evaporation) ceases, and its value is zero for any depth greater than the extinction depth.
When “Evaporation” is selected from the “BCs” drop-down menu on the Main Menu banner found at the top of the screen, the dialog box shown in Figure 7.43 appears. The required information for evaporation zones is described below. Similar to recharge zones, evaporation parameters must be defined prior to applying them to the model.
- Depth to Zero ET:
Extinction depth (depth below which there is zero evapotranspiration).
- Maximum ET Rate:
Maximum evapotranspiration rate (m/yr or ft/yr).
- Multiplier of ETMAX:
ETMAX is defined as the maximum evapotranspiration rate. This defines the multiplication factor of maximum evaporation for the time step. The multiplier of ETMAX can be defined as time-series data. The three options are constant, annual, and varied. Each is explained in the time-series data section (Section 7.4.1).
After defining the evapotranspiration zones, the plot item “2-D Plane” should be selected from the list provided in the “Control Panel.” In the “Color By” attribute, select “Evaporation.” Now, using the “Select” tool (see Chapter 6), elements can be selected and the newly created evaporation zones can be applied to the elements.
7.5 Initial Conditions¶
To solve the groundwater flow equation, MINEDW requires an initial estimate for the head values (initial conditions). The initial conditions can be specified by either defining a constant-head value or reading varied head data from a file created in a previous model run.
To define the initial conditions, select “Initial Heads” from the “Project” drop-down menu on the Main Menu banner found at the top of the screen, and the dialog box shown in Figure 7.44 appears.
The initial head for all the nodes is a constant value, which is input in the field provided.
The initial head for all the nodes is imported from a file created by a previous model run. MINEDW records the groundwater head for the entire model domain at the last time step of a model run in an .MDL file. This is done for both steady-state and transient model simulations. To use this information as the initial condition for a subsequent model run, click on “Varied” and then the “…” button to the right. Select the .MDL file from the folder where MINEDW previously ran (it must be the same model domain). The format of the .MDL file is 10 columns of head data. The length of the file will vary with the size of the model, but the head value corresponds to the nodes in the model beginning with the first node and ending with the last node, reading from left to right and top to bottom.
7.6 Mining Plan¶
MINEDW can simulate the progressive excavation of an open-pit mine. The simulation of open-pit excavation is performed by collapsing the elements (i.e., changing the z coordinates of nodes) in the finite-element mesh. The shape of the excavation is defined by the mine plan, usually provided as a 3-D .DXF file, and the excavation of the mine over time is simulated by interpolating between known pit geometries. There are two spatial interpolation options that can be used to calculate the new z coordinates of nodes as they are moved over time; these are explained in Section 7.6.1. The way in which the open-pit mine is excavated is based on either depth or volume, which is explained in the following paragraphs. Within the pit extent, a finer mesh area improves the accuracy of the simulated seepage face and pore-pressure distributions behind the pit wall.
To create a mining plan, select the “Mining” drop-down menu and then the “Create Mining Plan” function (Figure 7.45).
As described, the shape of the open pit is defined by XYZ data that may be provided as 3-D .DXF files by the mine for specific points in time. To simulate the excavation of the open pit between these known geometries, MINEDW provides two methods: depth and volume. Depth-based excavation simultaneously moves the pit surface outward in all directions, as shown in Figure 7.46. This is done by calculating the distance between two known open-pit geometries and dividing the distance by the number of time steps between the two dates associated with the geometries.
Volume-defined excavation will move the pit surface downward, rather than outward, toward the next known pit geometry, as shown in Figure 7.47. This is done by calculating the total volume to be excavated between two known geometries and dividing the volume by the number of time steps between the two dates associated with the geometries. This rate defines the volume of material excavated for each time step.
The “Create Mining Plan…” function will allow the user to combine both excavation methods when creating a mining plan only if open-pit geometries are provided.
7.6.1 Creating a Mining Plan¶
MINEDW provides the user with two options for entering the mine-plan information, which is used to create the mining-plan file used to simulate progressive excavation of an open pit. The first option is to provide XYZ data of the open pit over time in .DAT files (Section 220.127.116.11.). The second option is to provide XYZ data of the pit at the end of mining (ultimate pit) and pit-bottom elevations through time (Section 18.104.22.168).
If the XYZ data for pit topography is provided in 3-D .DXF files, they will need to be converted into .DAT file format before they are used to create a mining plan. The Rhino “Drop” function can be used to achieve this or any other program that is capable of manipulating .DXF files. Alternatively, MINEDW provides a function that can be used to convert .DXF files to .DAT file format (Section 22.214.171.124).
To create a mining plan, from the Main Menu banner click “Mining,” then select “Create Mining Plan.” The “Create Mining Plan” dialog box shown in Figure 7.48 appears.
In this menu, mining plans can be created using the following options:
- Interpolated With:
Select “Depth” or “Volume” methods for temporal interpolation.
- Input Data Directory:
The file path to the location where input files are located must be entered here. Two options are available: manual entry, or by clicking the “…” button, which opens the “Select Directory” dialog box. The “Select Directory” dialog box can be used to navigate to where the input files reside.
- Start Date:
Define the start date of the mining stage.
- End Date:
Define the end date of the mining stage. Periods of no excavation between mining stages can be created simply by ensuring that the start date of the next mining stage does not correspond with the end date of the previous stage. The mining periods for each of the stages, however, cannot overlap.
- Ultimate-Pit Outline File:
Enter pit boundary file name. This file is required to be in a .BLN format.
Add additional records to be used in the mining plan.
Insert additional records to be used in the mining plan.
Delete records used in the mining plan.
Open a mining-schedule file that contains a list of records to be used in a mining plan. The file format for a mining-schedule file is described in Appendix B.
Save a mine plan file. This will save the records of the mining plan to a file that can be imported again with the “Open” option.
Menu defining mining-plan spatial-interpolation options. MINEDW uses inverse distance weighting or kriging interpolation methods to create the progressive excavation of the open pit from data files that are provided by the user. The interpolation methods can be changed in the options menu of the “Create Mining Plan” menu. The options menu is displayed in Figure 7.49 below.
This menu has the following options:
- Inverse Distance:
Option to use the inverse-distance method for interpolation.
Option to use the kriging method for interpolation.
- Number of Points to Search:
Data points to use in the kriging or inverse-distance method.
Power used in the inverse-distance method.
Range used in the kriging method.
- Elevation Increase Is Not Allowed:
Option that does not allow elevation increases in the interpolation method.
- Duplicate Data Keep:
Option to determine which elevation is valid if two elevations exist at one point in one .DAT file. The user can either keep the minimum elevation, maximum elevation, or an average of the elevations.
126.96.36.199 Converting .DXF to .DAT files¶
Any .DXF file that will be used to create a mine plan needs to be converted to an XYZ data file (.DAT). To do so, on the “List” tab, double-click “File Data,” then double-click “DXF.” The “Attributes” tab appears. Select the “+” next to the “File” attribute as shown in the green box in Figure 7.50, and the “Select DXF data file” dialog box opens. Navigate to the location of the desired .DXF file, select it, and click “Open.” Next, select the icon next to “To Data File” to save the information from the .DXF file as a .DAT file. Repeat the same procedure for all mining .DXF files that are to be used in the mine plan. For .DXF files that have multiple layers, the user may choose the layers that will be used for the mine plan by activating or deactivating the layers using the “Layers” attribute.
For any pit plan that is created in MINEDW, a pit outline is needed (e.g., the ultimate-pit boundary) to define the nodes that will be used for interpolation. This boundary needs to be defined using a .BLN file format and is always the first record in the mine plan file. This file defines the perimeter of the pit and does not contain elevation information because all elevations are assumed to be the top of the mesh.
Note: All of the .DAT files that are used to create the mining plan file must be located in the same directory.
188.8.131.52 Creating a Mining Plan from Pit Topography files¶
The following is a guide to creating a mining plan and schedule based on XYZ data of pit topography stored in .DAT files.
From the Main Menu, click “Mining,” and then select “Create Mining Plan.” Enter the file path to where the pit topography files (.DAT file format) are located in the “Input Data Directory” box. Enter the name of the ultimate-pit boundary file in the “Ultimate Pit Outline File” box. Next, click “Add” to add a record to the “Create Mining Plan” dialog box for each of the pit topography files. For each of the pit topography files, enter the file name and the corresponding start and end date, and choose “Depth” or “Volume” under “Interpolated With.” Next, enter a name for the new mining plan file in the “Created Mining Plan File Name” box or, to select a different directory than the directory where the mining files are located, click the button next to the data entry box and select the desired file location and enter a file name (Figure 7.51).
Alternatively, the data detailed in the above steps can be imported from a “Mine Plan File.” If a “Mine Plan File” is available, click “Open…” in the “Create Mining Plan” dialog box and navigate to the location of the “Mine Plan File.” Select it and then click “Open.” The directory path, mining start date, ultimate-pit boundary file name, pit-geometry files, and associated dates will be populated. The default for “Interpolated With” is “Depth.” If the “Volume” method is desired, then be sure to select it for the appropriate mining stages. Finally, enter a name for the new mining plan file in the “Created Mining Plan File Name” box or, to select a different directory than the directory where the mining files are located, click the button next to the data entry box and select the desired file location and enter a file name.
When the appropriate data have been entered in the “Create Mining Plan” dialog box, click “OK” and MINEDW creates the mining file. The file will need to be imported into the model using the “Open Pit…” menu, which is discussed in more detail in Section 7.6.2.
184.108.40.206 Creating a Mining Plan from Final-Pit Topography¶
From the Main Menu banner, click “Mining,” and then select “Create Mining Plan.” Next, enter the name of the ultimate-pit boundary file in the box next to “Ultimate Pit Outline File.” Click “Add” to add a record to the “Create Mining Plan” dialog box and enter the name of the .DAT file containing the ultimate-pit topography. Enter the appropriate start and end date and file name under “Date” and “File,” respectively, for the ultimate pit.
Click “Insert” to add records above the previously created record. For these newly created records, enter the pit-bottom elevation and the start and end date in the “File/Elevation,” “Start Date,” and “End Date” columns (Figure 7.52).
Once the appropriate data have been entered in the “Create Mining Plan” dialog box, click “OK” to create the mining plan file.
7.6.2 Importing a Mine Plan into MINEDW¶
After creating the mine plan, select “Open Pit” in the “Mining” drop-down menu to assign the mining file to the model. After the “Open Pit” dialog box opens (Figure 7.53), click “Add” and browse to the mining plan file; select it and click “Open” in the “Open Mining Plan File” dialog box.
For each pit, there are four different menus: 1) “General,” 2) “Pit Lake,” 3) “ZOR,” and 4) “Backfilling.” Under the general tab, pit-plan information is provided, including the pit name, the start and end dates, and the pit-bottom elevations. In this menu, the user can open a different mining file using the “Replace with” command or create a different mining plan using the “Create” command. Under the other three tabs, a pit lake (Section 7.6.3), a zone of relaxation (ZOR) (Section 7.6.4), and backfilling (Section 7.6.5) can be defined.
Once a mining plan has been imported into MINEDW, the user may visualize the open-pit excavation through time by selecting the “List” tab in the “Control Panel” Pane on the right-hand side of the Main Menu and adding a “3-D Element” plot item. The mesh will be displayed in the View Pane in plan view with geological units. To view pit excavation at a particular time step, enter the time-step number in the box on the time-step slider; otherwise, click on the time-step slider (Figure 7.54) and move it to the right to view the progressive excavation of the pit through time.
The collapsed mesh showing the open pit with geology will be displayed in the View Pane, as shown in Figure 7.55.
The elevation change in the pit area through time can be visualized by selecting the “List” tab in the “Control Panel” Pane on the right-hand side of the Main Menu banner. Expand the “Node” item and double-click “3-D Contour.” The mesh will be displayed on the View Pane in plan view with elevation values. You can deactivate and activate “3-D Element” and “3-D Contour” to switch between the views at desired time steps to visualize the changes in both geology and elevation.
Mining plans for any model simulation can be activated and deactivated by unchecking the “Activate” checkbox. Click “OK” to save the changes and exit the “Open Pit” dialog box.
7.6.3 Pit Lake¶
When mine operations cease, a pit lake can form if the pit bottom is below the pre-mining water table. To simulate the pit-lake formation in MINEDW, select “Open Pit” from the “Mining” drop-down menu. In the “Open Pit” dialog box (Figure 7.56), select the pit plan that a pit lake forms under, and then select the “Pit Lake” tab and check the box next to “Activate.” To define a pit-lake simulation, enter a date in the “Start Date” box for the start of the pit-lake formation, an “Initial Lake Elevation,” “Evaporation” rate (if any), and the “# of Stages” in the lake. These options are described in more detail below.
The following options are available in the “Pit Lake” tab:
- Start Date:
Date of when pit-lake infilling will begin. This date must be after mining has ended and equal to or later than the backfilling date if backfilling is applied.
- Initial Lake Elevation:
This value must be equal to or greater than the minimum pit elevation or the pit bottom after backfilling operations. In the case of a sump or area of the pit that already holds water at the start of pit-lake formation, you would enter an “Initial Lake Elevation” greater than the pit bottom.
Evaporation rate of the pit lake (millimeters per year [mm/yr] or ft/yr).
- # of Stages:
Number of stages to be used in the simulation. The user must specify the “Elevation” of each stage in the dialog box below the input for the number of stages. MINEDW will calculate the “Area” and “Volume” of the stages.
The “Create” function will automatically calculate the area and volume of each stage based on the “# of Stages” the user selects.
Using the “Import” function, the user can import a pit-lake file.
- Additional Pump/Recharge:
Switch for additional sources of discharge (-) or recharge (+) (excluding groundwater seepage) when the elevation is lower than a user-specified elevation. When the pit-lake recharge option is activated, click the “Define Rate” button and a new menu (Figure 7.57) will appear. In this menu, the user can define any additional recharge and pumping to/from a pit lake based on time-series data.
7.6.4 Zone of Relaxation for Pit¶
In MINEDW, a ZOR can be created around excavations, backfilling operations, longwall coal mining, room-and-pillar coal mining, freeze-thaw conditions, or other scenarios in which hydraulic conductivity may change during the simulation period.
To create a ZOR for an open pit, select “Open Pit” from the “Mining” drop-down menu. Select the open-pit plan from the drop-down box in the upper left-hand corner of the dialog box and then select the “ZOR” tab (Figure 7.58).
MINEDW offers two options for specifying the thickness and shape of the ZOR: as a ratio of the pit depth or by user-defined thicknesses.
Using the first option, the user can further subdivide the ZOR into layers that are also defined using a thickness that is calculated as a ratio of the pit depth. This results in a ZOR that has a minimum thickness at the perimeter of the pit and thickens toward the center of the pit (Figure 7.59). Layering within the ZOR is defined in percentages of the total ZOR. The sum of user-defined percentages must be less than or equal to 100. In either case, MINEDW will add a layer such that the “ZOR Definition” dialog box will always contain n + 1 ZOR layers (where n is the number defined by the user) (Figure 7.58). The input file created by MINEDW will always contain n + 1 layers, but the layer added by MINEDW will only be used if the user-defined percentages are less than 100. For example, in a 120-m deep pit with a ZOR thickness equal to ¼ of the pit depth, the ZOR will have a maximum thickness of 30 m. The ZOR can then be divided into two equal layers by entering “2” in the box next to “# of Additional ZOR Layers” and then entering “50%” for both layers. When “Search Zone” is clicked, MINEDW adds an additional layer for a total of three ZOR layers, as displayed in Figure 7.59a. The ZOR layers that are used in the simulation are “Layer#1” and “Layer#2.” The layer added by MINEDW, “Layer#3,” is not used. Alternatively, the ZOR could have been created by creating one ZOR layer, entering “50%” for the layer, and then clicking “Search Zone.” In this scenario, the layer created by MINEDW is used and accounts for the remaining 50% of the ZOR (Figure 7.59b). Also, it is important to remember that, when MINEDW searches for geological units within the ZOR, it displays all the units for each layer even though the unit may not form part of the ZOR. For example, if the model contains a surficial unit such as alluvium that does not form part of the ZOR, it will be shown in the ZOR dialog window but can be excluded by using a factor of 1 for the hydraulic conductivity multiplier.
Using option two, in which the user defines the absolute thickness, the user specifies the number of layers in the ZOR and the thickness (m or ft) of each layer. The sum of these layers will be the ZOR thickness no matter the pit depth, as shown in Figure 7.60.
To create a ZOR using option one, click the “ZOR thickness = 1/ of Pit Depth” checkbox to activate the ZOR thickness proportionality option and then choose an appropriate ratio. Next, define the number of layers to use in the ZOR using the toggle buttons next to the “# of Additional ZOR Layers” box or by typing in a number. After that, specify the thickness as a percentage for each ZOR layer, keeping in mind that the cumulative sum of percentages must not exceed 100. MINEDW will provide the user a warning if the cumulative sum is greater than 100%. Layers are ordered from top down, where the top layer forms around the pit surface. Once layer percentages are defined, click the “Search ZOR Units” button and MINEDW finds the geological zones that lie within the defined ZOR. The “ZOR Definition” box, at the right (Figure 7.58), will contain the results.
To create a ZOR using option two, define the number of layers to use and the thickness of each layer, then click “Search ZOR Units.”
For either method, factors of the original hydraulic conductivity values are entered in the columns labeled “Layer#1,” “Layer#2,” etc. After finishing, click “Create ZOR” to create the ZOR for the open pit and then check the box next to “Activate” at the top left of the “Open Pit” dialog box. Click “OK” to save the changes and close the “Open Pit” dialog box.
Once a ZOR has been created, it can be visualized by selecting the “List” tab in the “Control Panel” Pane on the right-hand side of the Main Menu banner. Expand the “Element” item and double-click “Time Varied Conductivity” (Figure 7.61).
If the mining plan is modified or replaced with a different mining plan, the ZOR will need to be recreated.
7.6.5 Open-Pit Backfilling¶
MINEDW can simulate open-pit backfilling. Backfilling may be used in some mining applications to prevent the formation of a pit lake or to dispose of tailings after mining has ceased. To use this option, select “Open Pit” from the “Mining” drop-down menu. Select the desired pit plan on the left and then click the “Backfilling” tab (Figure 7.62). Check the “Activate” box and define the “Implement Date” for backfilling. The “Implement Date” of backfilling must be before or the same time as the “Start Date” of pit-lake formation. MINEDW does not support the backfilling of an existing pit lake and automatically adjusts the “Start Date” or “Implement Date” for pit-lake or backfilling operations to prevent backfilling of a pit lake. Backfilling operations are simulated in one time step rather than progressive backfilling over multiple time steps. The backfill elevation can be defined as constant by checking the “Constant Elevation” option and entering a value. Otherwise, if more detailed information is available for the backfill, “Varied” can be checked and the file containing elevation information, in .DAT file format, can be selected in the “Open Data File” dialog box that opens. In the “Grid” dialog box, choose the interpolation method and enter the appropriate parameters. The surface for the backfill is then created. Finally, the hydraulic parameters for the backfill can be selected from the drop-down list (Figure 7.62). The entire backfilled zone will have the same hydraulic properties and cannot be subdivided. When the “Backfilling” parameters are completely defined, click “OK” in the “Open Pit” dialog box to ensure that the changes are saved.
7.6.5 Zone of Relaxation for Caving¶
In MINEDW, the time-varied hydraulic conductivity related to the displacement of rock caused by underground mining can be simulated.
To create this hydrogeologic zone, select “Zone of Relaxation for Caving” from the “Mining” menu on the Main Menu banner. The “Create Zone of Relaxation for Cave Zone” dialog box appears (Figure 7.63). Information required for creating this hydrogeologic zone is described below.
- Mining Schedule:
The spatial extent of displaced rock over time due to block caving, which includes the date when the mining phase begins and the file names of 3-D .DXF files delimiting the extent of the inner and outer ZOR layers for the mining phase.
- ZOR Definition:
The factors by which hydraulic conductivity increases/decreases for each hydrogeologic zone that is displaced by caving.
Date and file name information can be entered manually in the “Mining Schedule” window or automatically using a mining schedule file. If “Mining Schedule” information is to be entered manually, enter the date when the first mining phase will begin and then enter the file name of the .DXF file defining the inner ZOR layer in the column labeled “Layer #1 File.” Next, enter the file name of the file defining the outer ZOR layer in the column labeled “Layer #2 File.” Click “Add” on the top right of the dialog box to add a new entry, and repeat the steps described above until the ZOR for caving is completely defined. To use a mining schedule file to enter information into the “Mining Schedule,” click “Open…” and locate the mining schedule file. Select it and then click “Open” in the “Open Caving ZOR File” dialog box. Note that MINEDW only supports two ZOR layers for caving, unlike the option for open pits, in which the user can define as many ZOR layers as desired.
After entering the necessary data, click “Search Zone.” The relevant hydrogeologic zone appears. Enter the factors by which hydraulic conductivity will change for each ZOR layer under the columns labeled “Layer #1” and “Layer #2.”
Enter the file name of the cave-zone ZOR file to be created in the box at the bottom of the “Create Zone of Relaxation for Cave Zone” dialog box and then click “OK.” To assign the created time-varied conductivity file for a cave zone to the model, please see the following section.
7.6.6 Dewatering and Underground Mining¶
The “Dewatering and Underground Mining” menu is used to assign the underground ZOR mining file to the model and to define groundwater recovery in the mined area at the end of mining. The drop-down box at the top of the dialog box contains a list of underground mines already defined (this list may be blank if none have been defined). The “Add” and “Delete” buttons to the right of the drop-down box are used to add or delete mines from the model. The “Dewatering and Underground Mining” dialog box is divided into three tabs: 1) “General,” 2) “ZOR,” and 3) “Recover” (Figure 7.64), which are explained below.
The following options are available in the “General” tab:
This checkbox is a switch to activate the selected underground mine in the model.
Defines the name of the underground mine.
- Drain Group Used:
This window is used to define the groups of drain nodes that are associated with a particular underground mine. This option does not affect how the model runs but does change the location of output. Drain groups that appear in the “Drain Groups Used” window also appear in the “Mine” column of the .BUD file and in the .MNE file. This option makes post-processing much easier but is not necessary to correctly set up a model run.
To assign the underground mining ZOR file to the model and define any groundwater recovery, select “Dewatering and Underground Mining” from the “Mining” drop-down menu. The “Dewatering and Underground Mining” dialog box (Figure 7.64) appears. Click the “Add” button, and the “General” tab becomes active. On this tab, the user can change the name of the mine, if desired, using the “Name” option. Next, select the drain groups associated with the underground mine from the drop-down box next to the “Drain Group Used” window and click “Add” to move the drain group to the “Drain Group Used” box. Click “OK” to save the changes and close the “Dewatering and Underground Mining” dialog box or select the “ZOR” tab to define the ZOR.
The “ZOR” tab is used to add the ZOR file created using the “Zone of Relaxation for Caving” dialog box to the model. The “ZOR” tab has the following options:
This checkbox is a switch to activate the ZOR for the selected underground mine in the model.
This button opens the “Open Time-Varied Conductivity File” dialog box, which is used to select the desired ZOR file.
Removes the ZOR from the underground-mine definition.
Opens the “Create Zone of Relaxation for Cave Zone” dialog box.
On the “ZOR” tab, locate the “Assign…” button at the bottom of the dialog box. Click the “Assign…” button and, using the “Open Time-Varied Conductivity File” dialog box, browse to the previously created ZOR file, select it, and click “Open.”
If the ZOR factors need to be altered, they can be updated using the “ZOR” tab (Figure 7.65). After all changes to the ZOR factors have been made, check the box next to “Activate” to activate the ZOR in the model.
Using the “Recover” menu, the user can define groundwater recovery and inflow into the underground workings after the end of mining. The “Recover” tab has the following options:
This checkbox is a switch to activate groundwater recovery for the selected underground mine in the model.
- Start Date:
Defines the start of groundwater recovery, which should be after the end of mining.
- # of Stages:
The number of stages to use to calculate groundwater inflow into the underground workings.
Function used to calculate the elevation and volume of each stage. This function is described in further detail below.
Function that can be used to import a file containing the stage elevation and volume relationship for groundwater recovery. The file format of this input file is detailed in Appendix B.
- Additional pumping/recharge; if elevation is lower than:
These options allow the user to define an elevation below which additional pumping or recharge is active.
- Define Rate:
This button opens a time-series window that is used to define the rate of additional pumping or recharge for groundwater elevations below the specified level.
On the “Recover” tab, define the “Start Date” of groundwater recovery and inflow into the underground workings. Next, specify the “Initial Lake Elevation” if the value MINEDW has automatically assigned is not desired. The default value is based on the lowest mined elevation. In the box next to “# of Stages,” enter the number of stages to use to calculate groundwater recovery in the underground workings. Note that if importing a file containing the stage elevation and volume recovery information, the “# of Stages” will be auto-populated. Next, click on “Create” to open the “Create Underground Recover Stage” dialog box shown in Figure 7.67 below. This function is used to calculate the stage elevation and volume information for groundwater recovery using a 3-D .DXF file and the “# of Stages” input by the user. The input for the dialog box is discussed below.
- DXF File:
Input for the file path and file name of the 3-D .DXF file to use to calculate the stage elevation and volume information for groundwater recovery.
- Maximum Elevation:
The maximum elevation of the underground workings.
- Minimum Elevation:
The minimum elevation of the underground workings.
- Stage Space:
The space of each stage, which is calculated by MINEDW based on the input 3˗D .DXF file and number of stages. This value can be modified by the user if necessary.
After selecting the appropriate .DXF file and verifying the MINEDW calculated information for the stages, click “OK” to close the window. The information for “Elevation” and “Volume” in the “Dewatering and Underground Mining” dialog box is automatically updated. If there is any additional pumping or recharge to be defined, check the “Additional pumping/recharge” box and enter the elevation below which additional pumping or recharge is active in the box to the right. Next, click the checkbox next to “Define Rate” to open the time-series window where pumping or recharge rates are defined. Figure 7.66 shows the “Recover” tab with the necessary input.
The “Backfill” tab in the “Dewatering and Underground Mining” dialog box is used to specify backfilling operations of an underground mine. The “Backfill” tab is shown above in Figure 7.68, and the inputs are discussed below.
Import will allow the user to import a file describing the backfilling of underground workings.
- Create Backfill:
This will open the “Create Zone of Relaxation for Cave Zone” dialog box, which will allow the user to create a file describing the backfill of the underground workings. The same procedures as described in Section 7.6.5 should be followed.
- Turn Off All Drain When Backfill:
This option will turn off all drain nodes that were used to simulate the dewatering of the underground workings. In order for this function to work, the appropriate drain node groups must be added to the “Drain Group Used” window on the “General” tab (Figure 7.64).
- Reference Node:
The node that is used for a reference elevation.