Module 2 - Identify the Contributing Watershed
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Step 1: Load data
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- Open the **Data Source Manager** and find the **ArcGIS REST** tab.
- Connect the **National Hydrography** data server.
- Select the **WBDHU12** Polygon layer.
- Click Add.

|hydrow016|

Step 2: Save one Watershed
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- Zoom to the **Agua Caliente** Watershed.
- Wait for the watershed polygons to load.
- Use the Select tool to select a watershed polygon.

.. note:: This watershed is already part of the project.
   Download it again to learn the process and to get an editable copy.

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Step 3: Polygon export
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It is easy to export a single watershed polygon or a group of watershed polygons as a **Project Domain**.
These can be used for FLO-2D or any other 2D model.

- Right click the **WBDHU12** layer and click **Export Data >> Save Features As**.

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- Fill the form and export the **Watershed Polygon**.

.. note:: This file needs to use EPSG:2222 because that is the project coordinate system.

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- Adjust the polygon style to remove the fill and make the outline heavier.

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Step 4: Load the Flow Lines
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- Open the **Data Manager** tool and load the **ArcGIS REST** tab.
- Select the **Hydrography** layer and click Connect.
- Select the **Flow Direction** Raster and click **ADD**.

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This project uses **Soldier Canyon** which is the streamline on the north-east side of the map.

.. important:: If the Flow Direction arrows are not visible, zoom in to a smaller area and 
   allow them to render. Once they display at a closer scale, they typically load more 
   efficiently when zooming back out to a larger extent.

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- Once the Flow Directions load, export it to a raster file.

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- Fill the form as shown and click OK.

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- Uncheck the source layer and move both layers to the **Watershed Group**.

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Step 5: Trim the Watershed Polygon
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The watershed polygon is too large so it can be trimmed manually or by running some watershed processing tools.

.. note:: 2D models do not require detailed watershed delineation. 
   This step provides a simple method to trim the polygon to the contributing drainage area.

- Select the Layer **Watershed Boundary 3857**.
- Click the **Edit Pencil**.
- Select the **Vertex Tool**.
- Delete the vertex points that are outside the flow line extent of the Project Area.

.. hint::
   Press Ctrl+Z to undo unintended deletions.
   If the changes are beyond recovery with Undo, toggle off editing mode and decline the save to revert to the last committed state.

- Once finished, toggle the **Editor Pencil** off and click **Save**.

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- This is the rough project extent.

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- The Area of Interest is here.

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Step 6: Create the Grid
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- Open the attributes table and toggle the **Edit Pencil** on.
- Set the Object ID to 20-ft or 30-ft and press the **Enter** to apply the changes.  (30-ft faster for training.)
- This field has just been reutilized for cell size.
- Save the edits and toggle the **Edit Pencil** off.

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- Click the **Create Grid** button.
- Fill the form as shown below and click **Ok**.

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- If desired, remove the **Hydrography Connected** Layers.
- Uncheck the Grid.
- Group the Watershed layers in the Watershed Group.

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.. |hydrow016| image:: ../img/hydrowkshp/hydrow016.jpg

.. |hydrow017| image:: ../img/hydrowkshp/hydrow017.jpg

.. |hydrow018| image:: ../img/hydrowkshp/hydrow018.jpg

.. |hydrow019| image:: ../img/hydrowkshp/hydrow019.png

.. |hydrow019a| image:: ../img/hydrowkshp/hydrow019a.png

.. |hydrow019b| image:: ../img/hydrowkshp/hydrow019b.png

.. |hydrow019c| image:: ../img/hydrowkshp/hydrow019c.png

.. |hydrow019d| image:: ../img/hydrowkshp/hydrow019d.png

.. |hydrow019e| image:: ../img/hydrowkshp/hydrow019e.png

.. |hydrow019f| image:: ../img/hydrowkshp/hydrow019f.png  

.. |hydrow019g| image:: ../img/hydrowkshp/hydrow019g.png

.. |hydrow019h| image:: ../img/hydrowkshp/hydrow019h.png

.. |hydrow019i| image:: ../img/hydrowkshp/hydrow019i.png

.. |hydrow019j| image:: ../img/hydrowkshp/hydrow019j.gif

.. |hydrow019k| image:: ../img/hydrowkshp/hydrow019k.png

.. |hydrow019l| image:: ../img/hydrowkshp/hydrow019l.png