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### Creating a new scenario

To create a new scenario, select the corresponding menu item from the GREAT-ER menu. A new dialog appears:

Figure 2.3: New Scenario Dialog

To create a new scenario you have to specify a scenario name at this stage. The name is used to identify the scenario in all further steps of GREAT-ER application. Optionally, you can select a substance and a catchment from related lists. Finally, you can enter a comment on the scenario to give additional remarks:

Figure 2.4: Scenario Comment Dialog

As an example, enter the name `GREAT-ER Tutorial` and select the substance LAS with the catchment Aire.

Leaving the New Scenario dialog with OK, you are asked to specify a scenario directory name. As mentioned above, each scenario is stored in a separate directory under the basic scenario directory specified during the installation process. The basic directory of the scenario database is displayed in the dialog. Enter a nonexistent subdirectory name (e.g. `tutorial`). The directory will then be created automatically.

Figure 2.5: Scenario Directory Dialog

Finally, to accomplish the generation of scenario data structures, two dialogs will be presented to you (Model Selection and Catchment Data). Once you are more familiar with the software you may use these dialogs to speed up the input process for a simulation. Currently you only have to leave them with "OK". The dialogs will be explained later in this tutorial.

The GREAT-ER user interface change after having operated the two dialogs:

Figure 2.6: Scenario Tutorial with Catchment Aire

The view now displays the Aire catchment with river network, discharge sites and catchment boundary, as mentioned in the view's table of contents. The discharge connection results from the fact that sewage treatment plants are situated at some distance from the discharged river. Usually the distance is too small to be seen on the full catchment scale. The site pictures theme is a very special theme which is only visible if photos are available to give users a better impression of the catchment. You are advised to never delete one of these themes.

The view title bar now gives some hints on the displayed data: the name of the scenario, the substance (with CAS-No. if available) and the catchment. The m in brackets warns users that there are unsaved changes. It can either appear for the scenario or the substance.

To also see the comments of a scenario, click with the right mouse button on the view. A dialog with the scenario settings will appear.

Figure 2.7: Scenario Information Dialog

The title bar of the ARCVIEW application now displays the name of the active scenario (see above). This is helpful if more than one scenarios are open and visible on the screen.

You may play around with the visible tools (identify, zoom, pan). The identify tool, which is implemented specially for GREAT-ER replacing the usual ARCVIEW identify tool, presents the attributes of selected geographic objects. As the tool considers all active themes (like the original identify tool) and due to the scale of detail, more than one object might be selected by a click. Their attributes are presented sequentially in separate dialogs. To see them all, click "OK", to abort "Cancel".

Figure 2.8: Identify Tool Dialog

Next: Needed inputs Up: Setting up a scenario Previous: Setting up a scenario