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Welcome screen (Step 1)

The Welcome screen gives some information about the steps within the wizard. These include:

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The DEM based network generation method (shown in Figure 1) requires a DEM, and divides the entire node-link network into sub-catchments based on a user-specified measure of upstream area (sometimes called stream threshold), usually for first-order streams. You can define points on the stream network where confluences between sub-catchment will be formed. The minimum sub-catchment area can also be modified. For example, in a node-link network spanning 1000 km², entering a stream threshold of 10 km² will produce approximately 100 sub-catchments.

The minimum sub-catchment area defines the drainage area at which headwater catchments can be formed (also known as drainage threshold or stream threshold). As a result, any link in the generated network will have a total upstream catchment area of at least this amount. Individual sub-catchment sizes will vary and some will be significantly smaller. Notably, where two connected nodes are very close together, the link between them will be short and the corresponding catchment can be very small.

Image Modified DEMs that have been derived only from contour maps or from other remote sensing technologies such as light detection and ranging (LIDAR) or shuttle terrain radar mapping (STRM) are usually not hydrologically correct. Such DEMs need to be adjusted to represent the flow of streams in the right direction. This is because they create a sense that there are spurious pits in the landscape when actually, none are present.

The Draw Network method (shown in Figure 2) allows you to define the networks manually, by loading a sub-catchment map (a raster with cell values set according to sub-catchment number) and then connecting sub-catchments by clicking and dragging using the mouse. This specifies how those sub-catchments are linked together by the node-link. You should use this method when you have previously defined the boundaries of your sub-catchments, either by using Source or an external program.

Image Modified You can create a draft of your sub-catchment boundaries using the DEM based network generation method, export those boundaries from Source, edit them in an external GIS program (for example combining or splitting sub-catchments), and then import your edited sub-catchment boundaries back into Source to create a revised sub-catchment node-link network using the Draw Network method.

DEM-based Network Generation

To use the DEM-based Network Generation method (shown in Figure 1):

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• Set the stream threshold to a large value (so that only a few sub-catchments are defined); and
• Load a list of nodes in one of the pre-defined formats.

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Note that the total area covered by the catchment can be viewed in the Recording Manager once the scenario has been run (Figure 3).

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Draw Network Method

To use the Draw Network method (Figure 3):

• Choose Draw Network from the Available Methods drop-down menu;
• Click Load Sub-catchment Map and open the desired sub-catchment raster file;
• Define the the direction of flow between the catchments by using one of two methods:
  1. Manual: Click and drag on the map to create a stream network by specifying the direction of flow between sub-catchments. Ensure a connection is also made from the lower-most sub-catchment to a point outside the sub-catchment.This is the catchment outlet, highlighted with a circle in Figure 4.
• Click Next once the network includes every sub-catchment and a corresponding outlet. You can rename the sub-catchments in the table under the Sub-catchment button.

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• 1. Automatic: Click Add Links from Shp File (shapefile) to load a shapefile of links that are then mapped to the sub-catchment map automatically. Each link must be defined in the shapefile as a polyline. The link (polyline) may have internal vertices, but these will usually be ignored. By default, the Geographic Wizard allows one link per catchment only, and will generate an error if the selected shapefile does not satisfy this rule. 
     1. Checking Allow Multiple Links per Catchment allows the user to load a shapefile with more than one link per catchment. Bifurcations are not permitted.
     2. Checking Use Internal Vertices will create separate links between internal vertices of a polyline (usually, links are only created between the polyline end points, and internal vertices are ignored).
• Click Next once the network includes every sub-catchment and a corresponding outlet. You can rename the sub-catchments in the table under the Sub-catchment button.

If you need to delete a link, right-click on the map and choose Draw Network. Continue drawing links as before.

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The other options in the list (Pan, Zoom, Copy graph and Properties) have the same function as that described for using the DEM based network generation method.

Additional buttons under Load Sub-catchment Map assist you in adding further detail to the network map. Load Gauge Map and Load Background Maps allow you to upload a shape file of gauges or an image like a stream flow map to assist in drawing the node-link network. Add Links from Shp file allows you to load a shape file of links that is then mapped to the sub-catchment map automatically.

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You must specify all possible functional units present in the area of interest, or that you want to represent in the scenario. There are three ways of defining FUs: manually, from a text file, or from a shape file (Figure 5). This is synonymous to the menu item Edit » Functional Units » List.

Figure 5. Geographic Wizard, Adding FUs manually

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By default, FUs are defined manually. Once added, they appear on the right under Functional Units.

• To add a FU, type it in the Name field, and either click Add or press carriage return; and
• To remove a FU, highlight it in the panel on the right and click Delete.

Using a shapefile

You can also import FU names from a shape file (Figure 6):

• Choose Specify from a Shapefile from the Available Methods drop-down menu;
• Click Load to upload a shape file that has been configured with a field for FU types; and
• Enable the layer(s) from the list and click Create. A list of FU names is generated in the right hand pane. The shape file used to define FU types will also be used to assign the areas to each FU in each sub-catchment.

Figure 6. Geographic Wizard, Adding FUs via a shapefile

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Using a text file

You can import FU names from a text file by choosing Import from a text file from the Available Methods drop-down menu. The format of the text file is shown in Figure 7.

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You must assign areas to every functional unit in each sub-catchment. The functional units that appear depend on those you defined previously. You can assign areas manually (using either the Table or Map tabs), or from a raster such as a land use map. This is synonymous to the menu item Edit » Functional Units » Assign Area....

To assign FU areas manually using the Table tab:

• Choose Manual Area Allocation from the Available Methods drop-down menu;
• For each sub-catchment, enter the area that is allocated to each FU. You can specify this as an absolute value in the Area (ha) column, or as a percentage in the Area (%) column; and
• You may enter the areas individually, or use the Apply-to options to fill multiple cells at once. This is explained in detail in the Using the Apply-to options section. You can also copy values from one cell and paste into other cells. Right-click on the source cell (the one you want to copy) and choose Copy. Then, right-click on the target cell, and choose Paste. The resulting table is shown in Figure 8.

Figure 8. Geographic Wizard, Assigning FU areas

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When assigning FU areas manually using the Map tab, you can view the entire catchment and its outlines. FU areas can be assigned as follows:

• Click on a sub-catchment that you want to assign a model to, or highlight several using the mouse (drag and select). Alternatively, use Ctrl to select several sub-catchments. If you hover the mouse over a selected sub-catchment you will see the its number or name;
• To assign the area covered by each FU to the selected sub-catchments, select a cell in the table you want to assign the area to; and
• Use the Apply-to options to assign the same area to the selected sub-catchment/FU combinations.

If the areal percentages per sub-catchment, do not sum to 100%, the percentage cell turns pale red (to indicate an error) for that sub-catchment. In Figure 9, SC # 1 (Urban FU), the area percentage should be 50, not 5. The error applies only to SC#1, so the cell for SC#2 is not pale red.

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Figure 10 shows the correct areal percentages for SC#1.

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You can assign areas to multiple FUs simultaneously, using the Apply-to options on the right of the screen. This is useful when you have a large number of sub-catchments, each containing several FUs.

• In the Area (ha) or Area (%) column, click in any cell;
• Enter a value or percentage;
• Specify the appropriate values in the Apply selected cell to: options (to the right of the table); and
• Click Apply, and the value will propagate through the specified sub-catchments and/or FUs.

To assign FU areas using a raster:

• Click Load to upload a raster file;
• If the land use map does not include a mapping of grid code to land use, click Assign Mapping;
• In the resulting window, assign a FU to each grid code using the drop-down menu in the FU column (Figure 11); and
• Click OK to close the Match FU Definitions to Raster window.

For each sub-catchment, the FU areas MUST add to 100% (+/- 0.1%). If areas do not sum to 100%, cells in the Area column will be shaded pale red. An exclamation mark will also appear on the left side of the first column.

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This step only appears if a catchment model plugin has been installed. It allows you to assign models to entire catchment or individual sub-catchments and it generally applies to catchments that model, for example, groundwater (for the GWLag Plugin). It is synonymous to choosing the menu item Edit » Catchments » Assign Models.

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This technique can be replicated for other Apply-to options available in the wizard. It can be used to:

• Assign a single value to all FUs across all sub-catchments;
• Assign a single value to all FUs in a particular sub-catchment (eg. 50% of the total area is assigned to each FUs in sub-catchment #9);
• Assign a single value to all FUs of a certain type (across all sub-catchments); or
• Re-allocate FU areas by value or percentage. For example, if you have already specified that 50% of each sub-catchment is of FU type "Forest", and 50% is of type "Urban", you could model increases in urban encroachment by specifying Auto-increase by 5%, all FUs of type "Urban" at the expense of all FUs of type "Forest". See Figure 12.

Ensure that the percentage values for each sub-catchment sum to 100% prior to re-allocating FU areas.

Figure 12. Automatically re-allocating FU area by percentage

Select Link/Node from the contextual menu. Click on the link you wish to delete; it will turn red. Press the Delete key on the keyboard or click Delete Selected elements on the right of the map. Ensure that you delete any unattached nodes that were connected to the deleted link. To re-draw links, right-click on the map and choose Draw Network. Continue drawing links as before.

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The other options in the list (Pan, Zoom, Copy graph and Properties) have the same function as that described for using the DEM based network generation method.

Additional buttons under Reference Points assist you in adding further detail to the network map. Load Gauge Map and Load Background Maps allow you to upload a shape file of gauges or an image like a stream flow map to assist in drawing the node-link network. 

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Specify FU Specify FU

Specify functional units (Step 4)

You must specify all possible functional units present in the area of interest, or that you want to represent in the scenario. There are three ways of defining FUs: manually, from a text file, or from a shape file (Figure 5). This is synonymous to the menu item Edit » Functional Units » List.

Figure 5. Geographic Wizard, Adding FUs manually

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By default, FUs are defined manually. Once added, they appear on the right under Functional Units.

• To add a FU, type it in the Name field, and either click Add or press carriage return; and
• To remove a FU, highlight it in the panel on the right and click Delete.

Using a shapefile

You can also import FU names from a shape file (Figure 6):

• Choose Specify from a Shapefile from the Available Methods drop-down menu;
• Click Load to upload a shape file that has been configured with a field for FU types; and
• Enable the layer(s) from the list and click Create. A list of FU names is generated in the right hand pane. The shape file used to define FU types will also be used to assign the areas to each FU in each sub-catchment.

Figure 6. Geographic Wizard, Adding FUs via a shapefile

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Using a text file

You can import FU names from a text file by choosing Import from a text file from the Available Methods drop-down menu. The format of the text file is shown in Figure 7.

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