The Geographic Wizard is the first in a series of steps required to create a catchments scenario. It consists of a structured sequence of windows that guides you through the process of defining the catchment area. On completion of the wizard, you will be presented with a node-link network. This figure outlines the outlines the sequence of steps in the wizard, with a more detailed explanation provided below.
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| Note: After a scenario has been created using the wizard, you cannot change the network, ie. you cannot merge or remove sub-catchcments. |
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. Once you have completed all steps, click Finish to close the wizard and view the catchment in the Geographic Editor. This figure also shows the action buttons that are visible at the bottom of every screen in the wizard.
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Figure 5. Manually adding functional units
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 text file
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Figure 6. Adding functional units via a text file
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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
- Select 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.
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| Note: In the shapefile, there should be no empty records in the column which is chosen to describe the FU classes. |
Figure 6. Adding FUs via a shapefile
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.
Figure 7. Adding functional units via a text file
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- 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 78.
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8. Assign areas to functional units
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:
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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 89, 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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89. Example of incorrect area values (SC#1)
Figure 910 shows the correct areal percentages for SC#1.
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910. Example of correct area values (SC#1)
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.
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- 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 1011); 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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1011. Assigning FU areas using a land use raster
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| Note: You can edit the FUs on completion of the wixard using the menu items. If the FU list is modified, you will have to update the units areas to reflect this modification. |
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- 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 1112.
Ensure that the percentage values for each sub-catchment sum to 100% prior to re-allocating FU areas.