Development of GeoSWMM 2D Project

GeoSWMM 2D Tools

GeoSWMM 2D modeling tools enable the user to create and assign attributes for 2D features in a GeoSWMM project. These tools will assist users to define a boundary layer within which the 2D model objects will be created with defined hydrologic parameters, create all the associated nodes, links to generate the 2D mesh, connect the 2D features with the 1D features through different connection options and generate flood extent rasters. Each tool requires pre-requisite layer(s) to process and generate next level of layer(s).  User need to follow the hierarchical process that is established within these tools to generate the subsequent output layer(s).

Table 11.2 : Pre-requisite and Output layers for 2D Modeling Tools

Defining Boundary Layer 

After migrating to 2D model, user can generate boundary layer features using the Define Boundary Layer tool. Without defining the boundary layer, 2D nodes and 2D network cannot be generated. User can create or import a boundary layer in the GeoSWMM project by:

1. 1. 1. 1. 1. Importing an existing layer and/or
            2. Drawing/Editing a new layer

The defined boundary layer will be saved within the project as Boundary Layer.

Note: While importing or creating a new boundary layer feature(s), GeoSWMM will process the primary data within a temporary layer called Working_Layer and will be added temporarily in the ArcGIS Pro map TOC. When the Boundary Layer import process is finished, all the features from this temporary layer will be copied to the project Boundary Layer

Importing Existing Layer(s)

User can import an existing polygon layer and define it as the Boundary Layer using this tool. Note that, existing boundary should contain the following attributes:

Table 11.3 : Required Attributes for Defining Boundary Layer

For details about the Boundary Layer Properties, check into Appendix B.3. Users need to map these fields while importing. In case of missing any field or if user doesn’t have the required field(s), the tool will assign the required field(s) with the default values mentioned in Project Defaults for Boundary Layer.

The steps for importing an existing polygon layer as a boundary layer have been described below:

• In Define Boundary Layer Tool, click on Import to import an existing layer as the boundary layer. Clicking the import button will lead the user to another window.

• In the Import Polygons to Boundary Layer window, user can select the polygon layer from the available layers in the drop-down option (if the layers are already in the TOC) or browse the desired layer(s) from the computer. Then Click  add button to add in the table

• You have to map the existing attributes of the imported layer with the required fields for the Boundary Layer.  In the Map Fields section, you will be able to specify the targeted fields from the drop-down at each cell.
• After finalizing the map fields, user can import the layer clicking on Import button. An ‘Import’ confirmation message will appear.

• After the successful import of an existing layer into the Boundary Layer, all the available features of the layer will become available in a list of the Define Boundary Layer tool. You can edit and change the attributes or values of different field(s) from the “Edit Attributes” table. For further addition or geometric update to any feature, user can draw new feature or can edit existing features by starting Create/Edit Polygon option. A successful import of a layer will append into the table with the available features of the imported layer.

Drawing New Features in The Boundary Layer

The same tool gives the provision of updating a new feature and edit the geometry of a feature within the boundary layer.

To update a new feature or to edit a current feature follow the following steps,

• Go to Edit to start drawing a new feature. Arc GIS Pro edit option will become active.

• Click on Create feature.

• Click on Working_Layer to draw polygon.

• Modify the vertices of the polygon.
• Stop the Edits
• Save the Edits.
• Press Update  button to update the polygon features for the Boundary Layer.

• New features will appear in the Edit Attributes table.
• User can update the required fields of the new feature manually from Edit Attributes table.

• Press “OK” to add the features in the project Boundary layer. If there’s any blank attribute(s) in the Edit Attributes table, the following message will appear. Press “Yes” to update the attributes with defaults values.  Press “No” to enter the attribute data in the table.

Editing an Existing Feature

Go to Edit tab and Press Edit  button. ArcGIS Pro edit section bar will become active.

Select the feature that is needed to be edited.

Click on Modify Features.

Click on Modify Features.

Select the Edit Vertices Option.

Select the Edit Vertices Option.

The vertices of the polygon will become editable.

You can edit the vertices position, add new vertices, remove vertices.

You can also use the editing tools like reshape feature, cut polygon, rotate and sketch properties.

Creating 2D Nodes

The Create 2D Nodes tool generate the 2D node points using the attribute assigned in the boundary layer. It works with a Digital Elevation Model (DEM) to generate the 2D cells and 2D junctions. The tool requires a DEM raster and a Boundary Layer as input. Assigning an Obstruction layer is optional. In this modeling approach, GeoSWMM allows to obstruct flow through Obstruction Layer which is expected to be polygon features. The output layer will be stored in the project geodatabase. User must manually edit or remove any 2D node features if desired.

The interface of this tool looks like the following Figure.

Steps:

Creating 2D Layers

The Create 2D Layer tool automatically creates features in the 2D network i.e Junction 2D, Conduit 2D and Cell 2D taking into account obstructions, boundary layer extent, and generated 2D nodes. The 2D mesh is formed through the rectangular open conduits between all adjacent cells. The tool also populates the required attributes of the 2D conduits, e.g., length, width, roughness etc.

All the required layer to generate 2D mesh will be assigned automatically from project details as it is already mapped from Create 2D nodes tool. User need to select the source from where junction’s invert elevation will be calculated.

The characteristics of the required input features in the Create 2D Layers tool are described below.

Bank Line

Bank Lines are used to define the main channel banks for a cross section. User can import Bank Lines from either a) ArcGIS Pro map TOC panel through the dropdown option or b) browse and add one or more polygon layer through the browse icon. The layer will be saved in project database. This option will remain inactive (by default) for this version of GeoSWMM2D

2D Nodes

2D nodes represent center points that will be used to create the subsequent 2D conduit and 2D cell layers. 2D nodes layer will be directly assigned in the “2D Layer Creation” tool from project GDB.

Elevation Data

When generating the 2D layer, the model will extract elevations from either the DEM layer at the locations of the 2D nodes or directly from the 2D Nodes created through the Create 2D Nodes tool.

The interface of this tool looks like the following Figure.

Steps:

Define Method from dropdown for 2D Layer generation.

Boundary Layer will be directly assigned from the Boundary definition tool where the layer is saved in the project gdb.

Obstruction Layer will be saved in the project details and directly assigned to the “2D Layer Creation” tool.

The DEM layer directory will be saved in the project details and directly assigned to the “2D Layer Creation” tool.

Bank Line option will remain inactive (by default) for this GeoSWMM 2D release.

2D Nodes layer will be directly assigned in the 2D Layer Creation tool from project GDB.

Extract Elevation Data can be assigned from:

Digital Elevation Model (DEM)

2D Nodes Layer

Click “Create 2D Layer” to generate the 2D Layers.

Connect 1D-2D

Connect 1D-2D tool allows user to connect existing 1D model to the 2D model. This tool can be found under “2D Modeling” option.  Before connecting 1D to 2D model, it is needed/prerequisite to create 2D mesh i.e 2D junction, 2D conduit and 2D cell. User can create 2D mesh using Create 2D Layers tool.

The interface of this tool looks like the following Figure.