< Previous70 Figure 5-12: Different configurations of the Cross-section plot for the Cross-section shown in Figure 5-11. 5.4.2 Cross-section Diagrams Cross-section Diagrams show modeling results such as solute concentration, velocity vectors, static head contours and static water line (blue dotted line at the top). Computational layers are separated by dotted lines (yellow dotted lines between the layers). The active computational layer in the cross section is bounded by a thick red line. An example is shown in Figure 5-13. 71 Figure 5-13: Example Cross-section Diagram. Default options/settings are shown. Users can change the vertical exaggeration factor of the cross-section by unchecking the radio box next to ‘Automatically’, and then single-clicking in the text-box next to ‘Vertical Exaggeration Factor’ to enter a different value. The plot can be enlarged by checking the radio box next to ‘Big Plot’ (see Figure 5-14 After making all desired changed, click on the ‘ReDraw’ button to update the plot. Figure 5-14: Customized Cross-section Diagram. The hydraulic conductivity (K) field is shown, with red colors indicating high K and bluer colors indicating low K. 5.5 3D Visualizations MAGNET allows the model parameters and simulation results to be viewed as a three-dimensional (3D) surface. An example of the chart interface is shown below in Figure 5-15. 72 Figure 5-15: Example 3D visualization of a model in MAGNET. If multiple layers exist in the model, use the scroll bars next to ‘GeoLayer:’ and ‘CompLayer:’ to change geological and/or computational layers, respectively15. Then click the ‘Surface Chart’ button to display the 3D model visualization. At any point, users can change the geological and/or computational layer and click the ‘Apply’ button to update the chart display. The layer being displayed in the chart can also be updated by using the ‘Layer UP’ and ‘Layer Down’ buttons available in the options menu (accessed by clicking on the red arrows – see above). The number in the text box next to ‘Index of Z’ indicates the layer of the model – ‘1’ corresponds to the bottommost sub/computational layer in a MAGNET model, while the largest number corresponds to the sub/computational topmost layer in a MAGNET model16. Use the drop-down menu next to ‘Surface’ to change the model variable being displayed. The options to choose from are shown in Figure 5-16. The color map used in the display can also be chosen from the list 15 In the Basic version of MAGNET, the number of geological/conceptual layers is restricted to one, and the number of computational layers is restricted to three. No such restrictions apply for the Premium version of MAGNET. 16 When multiple geological/conceptual are present (Premium Version only), the numbering scheme is the opposite: ‘1’ corresponds to the topmost conceptual layer in a MAGNET model, while the largest number corresponds to the bottommost layer in a MAGNET model 73 of variables shown in Figure 5-16. A legend is automatically generated based on the color map variable chosen. Table 5-2 shows the units used for each model variable available for display in the 3D Surface Plot. Figure 5-16: Model variables available for display in the 3D Surface Plot. Table 5-2: Units of model variables displayed in the 3D Surface Plot. Variable Units Top Elevation m Bottom Elevation m Aquifer Thickness m Head m Concentration ppm Velocity X, Y, Z m/d Conductivity m/d Transmissivity m2/d Use the text boxes next to ‘Rotation X:’, ‘Y:’, and ‘Z:’ to rotate the display about the X- (W-E), Y- (N-S) and Z- (vertical) axes. To adjust the vertical exaggeration factor, check the radio box next to ‘Use Zscale’, and enter the factor in the provided text-box. Check the ‘Log Scale’ radio box to display the model variable as log(variable), e.g., when displaying conductivity or transmissivity, which can vary many several orders of magnitude. Check the ‘Large Plot’ radio box to enlarge the chart display. By checking the ‘Show Elev Extension’ radio box, the extents of different geological/conceptual layers (Premium Version Only) will be showed along the sides of the 3D head distribution. After making all desired changed, click on the ‘ReDraw’ button to update the 3D Surface plot. 5.6 Particle Tracking A useful way to visualize groundwater flow is to perform traditional particle tracking, in which particles undergoing only advection are introduced at various locations in the flow model, and path lines and travel times are simulated and visualized. Particle tracking allows delineation of path lines in a flow model, which be used, e.g., to determine well capture zones, source water areas, and groundwater delivery mechanisms. 74 This section details the various ways options for placing and displacing particles during model development and simulation. The four options for placing particles includes: • placing particles around a well feature (see subsection 4.3.2) • drawing a rectangle filled with evenly-space particles • drawing a polygon with evenly-spaced particles • placing particles along a polyline The ‘ParticleTK’ button along the left-side of the MAGNET Modeling Environment (see Section 2.5) provides access to the tools need to place particles. Click on it to bring up the Particle pop-up menu (see Figure 5-17). Each tool is discussed in the following subsections. Figure 5-17: Particle Pop-up menu. As mentioned in subsection 4.3.2, options for displaying particles are available in the Default Model Parameters and Options menu. 5.6.1 Particles along a Polyline Select ‘ParticleLine’ from the Particle pop-up menu to place particles along a polyline. The cursor will become a cross-hair, allowing for placement of polyline vertices with single-clicks of the LM button. The polyline will appear as a series of bright yellow line segments with circles at the vertex locations (see Figure 5-18). The location can of any vertex can be changed by hovering the mouse over it and click-dragging to the new desired location. Once the last vertex has been placed, LM click the ‘SaveShape’ button to finalize the polyline. Run the model forward to perform forward particle tracking, or run the model backward for reverse particle tracking (see subsection 5.1.3 for details on running the model forward or backward). Note that if a particle feature is already present in the model before submitting for simulation, a prompt will help to determine if forward or backward particle tracking will be performed (see right). 75 Figure 5-18 provides an example of forward particle tracking of particles placed along a polyline in the bottom-right portion of the model domain. In this example, the path line of the particles is shown, which is the default setting for MAGNET. To remove particle pathlines (and instead only show the particle position at a given time), uncheck the radio box next to ‘Particle Tracking Continuous Pathlines’ in the Default Model Parameters and Options menu. Also note that this example utilizes a default particle size of one pixel. To change the particle size, enter a different value in the text box next to ‘Particle Size :’. Figure 5-18: Example of placing particles along a polyline and performing forward particle tracking. The number of particles that are placed (evenly-spaced) along the polyline is controlled by the value in the text box next to ‘Number Particle along a Line:’ in the Default Model Parameters and Options menu. Drawing a new Particle Polyline. The current version of MAGNET allows for only one particle polyline to be present at one time. If a particle polyline already exists in the model domain, selecting the ‘ParticleLine’ tool from the Particle pop-up menu will automatically remove the existing polyline, and the cursor will once more become a cross-hair for placing the new particle polyline. 5.6.2 Particles in a Zone Select ‘ParticleRect’ (rectangle) or ‘ParticleZone’ (polygon) from the Particle pop-up menu to place particles inside of a zone polyline. The cursor will become a cross-hair, allowing for placement of rectangle/ polygon vertices with single-clicks of the LM button. The zone will appear as a series of bright yellow line segments with circles at the vertex locations (see Figure 5-19). The location can of any vertex can be changed by hovering the mouse over it and click-dragging to the new desired location. Once the last vertex has been placed, LM click the ‘SaveShape’ button to finalize the particle zone. Figure 5-19 provides an example of forward particle tracking of particles placed in a zone in the central portion of the model domain. In this example, the path line of the particles is shown, which is the default setting for MAGNET. 76 Figure 5-19: Example of placing particles in a zone and performing reverse/backward particle tracking. The number of particles that are placed (evenly-spaced) within the zone is controlled by the value in the text box next to ‘Number Cols of Particle in a zone :’ in the Default Model Parameters and Options menu. The value entered represents the number of columns of particles to use to “fill” the zone. Drawing a new Particle Zone. The current version of MAGNET allows for only one particle zone to be present at one time. If a particle zone already exists in the model domain, selecting the ‘ParticleRect’ or ‘ParticleZone’ tool from the Particle pop-up menu will automatically remove the existing particle zone, and the cursor will once more become a cross-hair for placing the new particle zone. 5.6.3 Adding Dispersion Effects Dispersion can be incorporated into the particle tracking method in MAGNET. Enter a non-zero value (units: m2/day) in the text box next to ‘DiffL’ and/or ‘DiffT’ to include lateral (L) and transverse (T) molecular diffusion in the particle tracking simulations. Similarly enter a non-zero value in the text box next to ‘DispL’ and/or ‘DispT’ (units: m) to include lateral (L) and transverse (T) local dispersion in the particle tracking simulations. 5.6.4 Deleting and Resetting Particles To delete all existing particles from the model, select ‘DeleteParticle’ from the Particle pop-up menu. To reset particles to their initial position (“reset the particle clock”), select ‘DeleteParticle’ from the Particle pop-up menu. 77 Chapter 6 ANALYSIS & MODEL PERFORMANCE MAGNET offers several tools for real-time analysis of model results and comparison with observations. In particular, users can: • Monitor head and concentration simulation outputs and compare with time-series measurements at a discrete location. • Compute water balances for a zone or set of zones • Compare head measurements across space, either within the entire modeling domain or for a subregion of the domain. Each of these is explained in further detail in the following sub-sections. 6.1 Monitoring Well Time-Series and Breakthrough Curves Monitoring wells are useful for visualizing time-series head and concentration data at a discrete location in the model domain. Subsection 4.3.3 provided details on how to make any well feature a monitoring well. As discussed in Section 5.4, to view Charts of model results, LM click on the ‘ViewResult’ button along the left-side of the MAGNET Modeling Environment, then select ‘Display Charts’ from the pop-up menu. This launches five different charts, including the Monitoring Well plot.. An example of a using a monitoring well to generate a concentration breakthrough curve is shown in Figure 6-1. Note that the ‘Time’ axis is in units of days since the start of the simulation, and the ‘Concentration’ axis is in units of ppm. An example of using a monitoring well to visualize time-series simulated head data is shown in Figure 6-2. Again, the ‘Time’ axis is in units of days since the start of the simulation. Head is in units of meters. The Monitoring well plot only shows the results of one monitoring well feature at a time. To show the results for a different feature, use the drop down menu next to ‘Select MW:’ to select a different feature, then click ‘ReDraw’ to update the plot. Observations of head or concentration can be added to the Monitoring Well plot. See subsection 4.3.3 for more details. 78 Figure 6-1: Example of using a monitoring well to generate a concentration breakthrough curve. Figure 6-2: Example of using a monitoring well to visualize time-series simulated head data. 6.2 Water Balance Analyses 79 Zone budget (water balances) analyses can be conducted for: • the entire model domain • any zone added to the model domain • a single grid cell of the model A zone budget is automatically created for the model domain every time a model is submitted for simulation. As discussed in Section 5.4, to view Charts of model results, LM click on the ‘ViewResult’ button along the left-side of the MAGNET Modeling Environment, then select ‘Display Charts’ from the pop-up menu. This launches five different charts, including the Mass Balance Bar Chart. Example Mass Balance Bar Charts are shown in Figure 6-3. Positive fluxes represent sources of water to the zone/domain, while negative fluxes represent sinks of water. Default units are cubic feet per second (CFS), but users can change the units to gallons per minute (GPM) or cubic meters per day (m3/day) by using the drop-down menu next to ‘Unit’. Any changes made require that the ‘ReDraw’ button is selected before the chart is updated. Directly below the Mass Balance Bar Chart, the fluxes of the different budget terms are listed so that the user may export the information, if desired. The following defines the different terms possibly present in a water balance and/or text output window: • Bnd – water flux entering or leaving the zone through a boundary • Csth – water flux from or moving to a constant head boundary condition • Well (in bar chart) – water flux injected or removed from a injection/pumping well • Rech – water flux added to the zone/domain from recharge • Drain – water leaving the zone/domain through one-way head-dependent boundary conditions (drain or surface seepage) • Error – residual of the zone budget. This is typically very small, unless there are issues with the model conceptualization or solution process. • East – water flux added/removed through the eastern lateral zone boundary • West – water flux added/removed through the western lateral zone boundary • North – water flux added/removed through the northern lateral zone boundary • South – water flux added/removed through the southern lateral zone boundary • Top – water flux add/removed through the top cell/zone boundary (for multi-layer models) • Bottom– water flux add/removed through the nbottom cell/zone boundary (for multi-layer models) • Qwell (in text output window) - water flux injected or removed from a injection/pumping well • Qrech (in text output window) - water flux added to the zone/domain from recharge • Qriv • Qdrn • Qhde – • Qevt – flux removed due to evapotranspiration • Qret – flux added from return flow. If the model domain lacks and zone conceptual features, the Mass Balance Bar Chart will show the zone budget for the entire model domain (see top-right graphic in Figure 6-3). Select the radio button next to ‘Zone’ to show the zone budget for any zone(s) within the model domain. The drop-down menu allows for selecting from different zones in the model domain, if applicable (see Next >