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If some data or parameter values are unavailable whilst creating the scenario, skip the step by clicking Next. Once you have created a scenario, you can make changes using the choices on the Edit menu.
In some situations, the wizard will skip over several steps if certain values have not been specified. For example, if you do not define any constituents (step 4), you cannot assign inputs or parameterise any constituent-related steps. Therefore, steps 8-13 will appear greyed out in the wizard progress indicator (Figure 2). This figure also shows the action buttons that are visible at the bottom of every screen in the wizard.
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On completion of a step, you can move to the next step by clicking Next and backwards by selecting Back. Note that you cannot go back to the network definition step once you have completed it and moved to the next step. Cancel allows you to quit the wizard at any time. Note that you will lose all the data entered so far. You can also complete the scenario if the Finish button is active (from step 7 onwards). Source will create a scenario when all mandatory steps have been completed, even if all the steps in the wizard have not been completed.
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| Note: Most of the windows appearing in the wizard are identical to the related Edit menu choices. For steps that are related to rainfall runoff, constituent generation and filter models and have screen output similar to the wizard, refer to the Constituents and Rainfall runoff models chapters. |
Welcome screen (Step 1)
The Welcome screen gives some information about the steps within the wizard. These include:
Specifying the catchment network;
Creating a list of the constituents and functional units that will be used in the scenario;
Assigning functional unit areas and models to rainfall runoff, constituent generation, filters, node and links;
Selecting input files for the rainfall runoff models; and
Setting parameter values for models assigned in the node-link network.
Name the scenario (Step 2)
Enter a scenario name and an appropriate description, or accept the defaults.
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You must define the sub-catchments and stream network within the catchment, using either a catchment map or Digital Elevation Model (DEM).
The DEM based network generation method 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 km2km2, entering a stream threshold of 10 km2 km2 will produce approximately 100 sub-catchments.
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- Choose DEM based network generation from the Available Methods drop-down menu;
- Click Load DEM;
- Navigate to the catchment DEM and open it. Source generates a default network based on a minimum sub-catchment area of 50 km2. It is recommended that you specify the minimum sub-catchment area prior to loading a high resolution DEM to reduce computational time;
- Specify a different minimum sub-catchment area in km2, if necessary, and click Recompute Streams. The drainage density depends on the minimum sub-catchment area; and
- Select a desired catchment outlet (a point in the network where all streams in the desired area converge) for investigation by clicking inside the map. This generates a network area broken into sub-catchments (shaded blue), where two sub-catchments converge at a confluence.
Figure 32 shows an example of a sub-catchment network.
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Once a DEM has been loaded, you can alter it by right-clicking and choosing the various options available in the contextual menu:
- To add a new catchment outlet, choose Select Cell from the contextual menu, and select another point on the catchment map; or
- Pan allows you to move the map up, down, left or right; or
- To zoom in, right-click, and choose Zoom In. Drag the mouse to form a zoom box (top right to lower left). To zoom out, double-click anywhere on the map or click Undo Zoom; or
- To remove a catchment outlet point, choose Remove Cell; or
- Choose Properties to change the attributes of various elements, such as the colour or symbol of nodes; or
- Save allows you to save the map as a .asc file.
Adding nodes
Ordinarily, nodes are placed at stream confluences identified in a DEM analysis. It is possible to supplement these nodes and place additional nodes at different locations, typically to identify some point of interest, such as a gauging station of a dam wall. This will also cause additional subcatchments sub-catchments to be created.
Additional nodes are added from a file of geographic points (eg .MIF, .SHP, .tsd). The points are automatically added to the streams and become nodes and catchment boundaries in the network. There is the potential for this automated process to give erroneous results, so it is important to understand the process used to ‘snap’ to the stream.
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You can set Source to recalculate networks manually by enabling Multiple Outlets. Then, select multiple points/cells on the DEM as required and click Generate Network.
Additional buttons under Multiple Outlets allow you to work with outlet nodes:
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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 1333).
Figure
1333. Recording Manager, View Catchment Areal
To use the Draw Network method:
- Choose Draw Network from the Available Methods drop-down menu;
- Click Load Sub-catchment Map and open the desired sub-catchment raster file;
- 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 1344.
- 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 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.
Figure
1344. Network definition by drawing
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.
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| If all the sub-catchments have not been connected, they will be shaded in blue. All sub-catchments must be connected by links before you can click Next (Figure 1355). |
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1355. Incomplete connection of sub-catchments
Define constituents (Step 4)
Enter a list of constituents that are of interest and which you wish to model. If you do not enter any constituents, the wizard does not display any steps that are constituent-related ie the constituent generation, filter assignment and filter parameterisation steps appear greyed out. Examples of constituents are total nitrogen (often abbreviated as TN), total suspended sediment (TSS), heat, dissolved oxygen, radioisotope tracers, etc.
Constituents cannot be deleted once they have been added and the Configure... dialog has been closed. |
You can also add constituents after a scenario is set up using Edit » Constituents, which opens the Configure Constiuents dialog (Figure). Refer to Defining constituents for more detail. To add a constituent, type its abbreviation in the Name field and either click Add or press the carriage return. To remove a constituent, highlight it and click Delete.
Specify functional units (Step 5)
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 136).
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