Template:GSSHA Define and Smooth Streams Workflow

1. Create GSSHA map coverage

1. Create new coverage from scratch. Select Map Data in the Project Explorer and use the New Coverage right-click command. Use the New Coverage dialog to create a new coverage by selecting the desired coverage type, and naming the coverage. 2. Create new coverage from an existing coverage. Use the Duplicate command on an existing coverage. This will copy any feature objects on the coverage. Use the Rename command to give the coverage a new name. Change the coverage type.

2. Stream arc creation

1. Create feature arcs, nodes and vertices. In the Map module, create feature objects in the active coverage. Use the Create Feature Arc tool to create arcs in the map coverage. Begin creating a new arc by clicking in the Graphics Window at either arc end. If clicking on an existing feature node, vertex or arc, the new arc will snap to that object. Double-click or press the Enter key to terminate the arc. Use the Create Feature Node tool to create additional nodes alone or to split arcs. 2. Modify arcs. Feature arcs often need to be edited after initial creation. 1. Create additional vertices on arcs. Use the Create Feature Vertex tool to add vertices along arcs. 2. Refine the arc shape. Use the Select Feature Vertex tool and the Select Feature Node tool to move/edit existing arcs and refine the shape by dragging the nodes/vertices. Use the Select Feature Arc tool to move entire arcs . 3. Split arcs. An existing arc can be split by: 1. Converting a vertex to a node. Use the Select Feature Vertex tool and right-click on a vertex along an arc. Select the Convert to Node command to split the arc into two arcs. 2. Add a node the arc. Use the Create Feature Node tool to add a node on an arc in order to split it into two arcs. 3. Add a new connecting arc. Use the Create Feature Arc tool to start or end a new arc on an existing arc to split the existing arc into two arcs. 4. Use the Split Arcs Tool. Right-click on an arc using the Select Feature Arc tool and select the Split Arc(s)... command. Use the Split Arcs Tool to divide arcs. 5. Split overlapping arcs using the Clean Options dialog. Select overlapping arcs using the Select Feature Arc tool. Use the Feature Objects | Clean command to bring up the Clean Options dialog. Select the Intersect selected arcs option (for selected arcs) or Intersect arcs option (for all overlapping arcs) to split the arcs. 4. Merge arcs. Two arcs that share an end node can be merged together. Select the shared node using the Select Feature Node tool. Right-click on the node and select the Convert to Vertex command to merge the arcs. If desired, the Select Feature Vertex tool can be used to select and delete the new vertex. 5. Smooth arcs. The variability or roughness of an arc can be reduced. Right-click on an arc using the Select Feature Arc tool and select the Smooth Arc(s)... command. Use the Smooth Arcs Tool to reduce the variability of the arc. 6. Prune arcs. Concave sections of the arc can be removed. Right-click on an arc using the Select Feature Arc tool and select the Prune Arc(s)... command. Use the Prune Arcs dialog to remove concave sections. 7. Extend/trim arcs. Extend or shorten an arc to match an existing arc's length. Using the Select Feature Arc tool, select two intersecting arcs. Right-click on an arc using the Select Feature Arc tool and select the Extend/Trim Arc... command. Use the Trim/Extend Arc dialog to select the target arc and source arc.

3. Interpolate elevations to coverage

1. Convert image data. 1. Convert raster data to feature contours. Right-click on the raster image and select the Convert To | Feature Contours command to create a new map coverage with elevation contours. 2. Convert raster data to feature contours at a specified elevation. Right-click on the raster image and select the Convert To | Feature Contours at Given Elevation command. In the Create Contour Arc dialog, specify an elevation and click OK to generate a map coverage with contours created along the specified elevation. 3. Convert raster data to scatter set. Right-click on the raster image and select the Convert To | 2D Scatter command. In the Raster → Scatter dialog, give the scatter set a name and click OK to generate the scatter set. 4. Convert image data to 2D grid. Right-click on the raster image and select the Convert To | 2D Grid command. 5. Convert raster data to flood depth raster. A water surface elevation dataset must be available in the project for this process to function. Right-click on the raster image and select the Convert To | Flood Depths command. In the Select Geometry and Dataset dialog, select the geometry containing the water surface elevation dataset and then select the water surface elevation dataset. Save the new raster with the inundated depth data. 2. Interpolate image data. 1. Interpolate raster data to active coverage. Select and make active the map coverage where the raster data is to be interpolated. Right-click on the raster image and select the Interpolate | Active Coverage command. 2. Interpolate raster data to 2D Mesh. Select and make active the mesh where the raster data is to be interpolated. Right-click on the raster image and select the Interpolate | 2D Mesh command. 3. Interpolate raster data to scatter set. Select and make active the scatter set where the raster data is to be interpolated. Right-click on the raster image and select the Interpolate | 2D Scatter command. 4. Interpolate image data to 2D grid. Select and make active the 2D grid where the raster data is to be interpolated. Right-click on the raster image and select the Interpolate To | 2D Grid command.

4. Assign arc properties
Select all arcs, right-click, and open the Arc Properties dialog and enter parameters. Double-click on most downstream arc, opening Arc Properties dialog, and turn on Most downstream arc of stream network. Use Display Options settings to show arc directions.

5. Correct arc directions
If any arcs do not show as flowing towards the most downstream arc, correct it by doing one of the following: Right-click on the arc and use the Reverse Arc Direction command Or open the Toolbox and use the Reorient Stream Arcs tool.

6. Smooth streams
Using the Select Feature Arc tool, select arc(s) and use the Redistribute right-click command. Use the Redistribute Vertices dialog to set the vertex distribution. Open the Toolbox . Open the Remove Adverse Slopes Tool and urn the tool.