Applying
the ArcGIS Hydro Data Model
Original
document was prepared by: Reem Zoun, Kristina Schneider, Tim Whiteaker, and David
Maidment,
This portion of the Arc Hydro exercise assumes that you’ve already prepared the data for schema application and you have available a set of prepared files in an ArcHydro geodatabase. Application of the Arc Hydro tools requires a completely connected geometric network.
You will need the following files to complete this exercise:
ArcHydro.mdb: the geodatabase you’ll use in this exercise (pictured below)
ArcHydroFrameworkSchema.mdb: the schema that will be applied this geodatabase
Make a copy of the ArcHydro.mdb and rename the copy to ArcHydro2.mdb. This copy serves as an original copy so that you can examine the change after applying the UML.
What you are beginning with is a draft ArcHydro.mdb database that looks like this:
3. Applying the Schema
A. Add the schema creation wizard to ArcCatalog
If the schema creation wizard 
has already been added
to ArcCatalog, skip to step 3.B, Connect to the Repository.
(1) Right click in the gray area in ArcCatalog where the buttons are and click Customize. You can also click Customize under the Tools menu.
(2) Click the Commands tab.
(3) Click “Case Tools” in the categories list.
(4) Drag the Schema Wizard command onto a toolbar.
(5) Click Close.
B. Connect to the Repository
(1) In the ArcCatalog tree, click the ArcHydro geodatabase to which you will apply the schema, so that it opens and you can see the feature dataset it contains.
(2) Click the Case Schema Creation button to launch the Schema Creation Wizard. You may get a message saying that this action requires an ArcGIS or ArcEditor version of ArcGIS. In that event, go to Programs/ArcGIS/Desktop Administrator and set the seat to ArcGIS or ArcEditor.
(3) Click Next to skip the introduction step, select the “Model stored in Repository database”, and then click Browse to select the repository database (in this exercise, ArcHydroFrameworkSchema.MDB). Ignore User Name and Password Requirement if asked for. Click Next to continue.
(4) Click the name of the object model in the repository for which you want to generate schema (ArcHydroFramework Data Model:: ArcHydroFramework).
(5) Click Next. This process may take a few minutes. A screen might appear asking you if you would like to use default values or values from a previous run. Select to use the default values. Press Next.
A tree-view of the schema represented in the model is displayed. Using this tree-view, you will now select the object classes (tables), feature datasets, and feature classes from your UML model for which you want to generate schema. The feature classes, highlighted with red, have been detected by the schema creation wizard since they have the correct Arc Hydro Framework name.
C. Set properties of feature classes
(1) Double Double-Click on “Watershed” and a dialog box for Watershed Properties will appear.
(2) Click on the Exists tab. Note near the top of the window that there is a check mark by “Feature class already exists in database” and the Watershed is listed in the Feature Class box. In this window you will match fields that were defined in the UML model to those that already exist in the Watershed feature class.
(3) In the “In existing object” column, click on “click to select” in the HydroID row. HydroID does not currently exist in the Watershed feature class; so select <Add Field> to add the field from the dropdown menu bar that is presented.
(4) Repeat step (6) for all unmatched UML classes.
Your Dialog box should look like this after you have matched all fields:
(5) Click OK and you will go back to Schema Wizard.
(6) Repeat steps 4, 5, 6, 7 & 8 for all feature classes in ArcHydro. You should have <Add Field> for any unmatched fields in all existing classes. Don’t worry about the HydroNetwork_Junctions class since it is empty and we don’t need it.
(7) Click OK to return to the Schema Wizard.
E. Create the schema
Once you have connected to the repository and selected the classes from your UML model for which you want to generate schema, the last part of the Schema Wizard is to actually create the schema in the geodatabase.
(1) Click Next.
At this point, you could review the options you specified in the Schema Wizard. If you wanted to change anything, you would click Back and change the appropriate parameters.
(2) Click Finish to generate the schema in the geodatabase. The generation may take a while. Say No to if you wanted to see the log file (or Yes if you wanted to see the log file!).
Congratulations! You have generated a schema!
View the feature classes that you’ve just worked on in ArcMap. Open the attribute tables in both ArcHydro and ArcHydro2 and you’ll see that what you have done is to create a series of additional attributes at the right hand end of your attribute tables.