Create a flood simulation scenario

To run a flood simulation scenario, you must first add a flood simulation layer to a 3D scene and configure the flood scenario.

Add a flood simulation layer

To add a flood simulation layer to a scene, complete the following steps:

1. Create a scene with a reliable ground elevation source.

   Examples include raster images and elevation services.

   Tip:

   Keep the following in mind:

   • It is recommended that you use a local scene with a projected coordinate system, such as a UTM zone.
   • A simulation can be viewed at different simulation times in multiple views of the same scene. Changing the configuration of a simulation layer will be applied to all views of that scene.

2. Optionally, add other 3D vector content relevant to flooding, such as buildings and dam walls.

   These 3D objects are also captured in the elevation surface used for the simulation.

3. On the Analysis ribbon, in the Workflows group, expand the Simulation drop-down gallery , and select a preset:
   • Default —A flood simulation layer with no preset water
   • Rainfall —A flood simulation layer with heavy showers
   • Water Source —A flood simulation layer with a water source in the center

   The simulation toolbar appears.

4. Specify an area of interest using one of the options:
   • Centered Location —Click a center location and a distance from it. The is the default method.

     Tip:

     Press R to define a specific radius.

   • Oriented Rectangle —Sketch a rectangle.
   • Area from Selected Features —Use the extent of the selected features.
   • Area from Selected Layer —Use the extent of the selected layers.
   • Area from Map —Use the map's extent.
   • Area from Camera View —Use the current camera view.
5. Click the Create Simulation in Area button to create the simulation.

   The flood simulation layer is added to the Simulations category in the Contents pane, and the Configure Simulation pane appears. Dimensions of the area of interest are listed in the pane. These include: length, width, rotation, cell size, and the resolution.

   Tip:

   If the area of interest is difficult to see, expand the simulation layer in the Contents pane and right-click the Area of Interest symbol to choose a different color from the color palette.

Note:

• If the map extent is larger than the current view, the area of interest is created at the center of the map extent and the view zooms to that extent.
• The maximum cell size for a simulation layer is 3.5 meters. This means the extent of the area cannot exceed 3.5 times the maximum processing resolution in length. For example, a simulation layer with a maximum processing resolution of 4096 has a maximum physical size of 4096 x 3.5m, or 14.3km. If you try to make it larger, a warning appears and the area is clipped to the maximum value.
• The maximum processing resolution of the simulation is limited, and can be set to one of three levels: 2048, 4096, or 8192. Higher-resolution processing requires more resources, and performance depends on the quality and specifications of your hardware, in particular the graphics card.
  • The default maximum processing resolution for new simulation layers is defined in the application settings. From the Project tab, click Options to open the Options dialog box. On the Map and Scene tab, expand the Flood Simulation Cache heading.
  • You can override this value for individual simulation layers using the Maximum Fit control in the Active group of the Simulation tab.
• As the extent of the area of interest increases, the cell size used for the analysis also increases. For example, a 2 kilometer by 2 kilometer extent with a 4096 processing resolution uses a 0.49-meter cell size, while an 8 kilometer by 8 kilometer extent uses a 1.95-meter cell size.
• Turn off the Maximum Fit button to manually adjust the cell size. By default, this option is on and the cell size is automatically calculated. Click the drop-down gallery to choose a new maximum resolution. The maximum cell size updates.
• In some cases, if you decrease the maximum resolution small enough, the area of interest dimensions are reduced.
• If the area of interest is copied from a scene that has a different coordinate system, the area of interest is reprojected to match, which may result in dimension changes.

Configure the flood scenario

To configure how water, such as rainfall and water source points, behaves in the simulation and which layers participate to customize the scenario, complete the following steps:

1. Right-click the simulation layer in the Contents pane and click Configuration to open the Configure Simulation pane if necessary.

   Alternatively, on the Simulation tab, in the Configuration group, click the Simulation Configuration launcher .

   The Configure Simulation pane appears.

2. In the Configure Simulation pane, define the overall simulation duration.
3. Provide one or more Rainfall Rate values and their duration.

   Note:

   • Provide multiple rows of rain to show changes through time.
   • Include a Rainfall rate transition time value in minutes to smooth the transition between rate changes.
   • At least one duration value is required, even if the rainfall rate is 0.
   • Use the gray row header to rearrange, move, and remove rainfall rate duration rows.

4. Define the layers that will participate in the simulation using one of the following:
   • Visible—All visible layers are included. This is the default.
   • Custom—Ignore layer visibility and manually define the participating layers.
5. Optionally, add a starting Water Depth Raster value and define the depth units.

   Note:

   The initial water depth adds water to the area of interest before the simulation starts.

6. Optionally, add infiltration properties.

   You can use a raster to define varying rates of infiltration over the area of interest or choose a fixed infiltration rate for the entire area. Infiltration removes water from the area of interest during the simulation to represent water infiltrating into the ground over time. The same applies for the maximum infiltration, which defines when water stops entering the ground.

7. Optionally, add an overall evaporation rate.

   You can model a fixed evaporation rate for the simulation. To do this, type the evaporation rate per hour in the Evaporation/hr text box in the Configuration group of the Simulation tab. The units are required to match the rainfall units.

8. Optionally, enable the Contain water within the area of interest option to prohibit water from exiting the defined area of interest.

   This is useful when the simulation should mimic a localized flooding event.

9. Click Apply.

   The configuration changes are saved to the simulation layer.

Run the flood scenario

Once the simulation layer has been added and configured, the flood simulation can be performed. To do this, click the Run button in the Build group of the Simulation tab. Once clicked, an analytical elevation surface is created, using either the visible layers or the specified custom set of layers, and the calculated water movement and pooling are displayed in the view.

As the simulation runs, a cache of key moments is built. Playback controls can be used to replay or step through the results.

If changes are made to the configuration, the simulation must be rerun and the cache rebuilt to show the new results.

Note:

Symbology changes do not require the scenario to be rerun.