Available with Advanced license.
Flood simulation uses shallow water equations within a defined area of interest to model how water moves and accumulates in a scene. You create one or more flood simulation layers in a scene, run the scenario, and review the visual results. You can adjust the scenario, such as increasing the rainfall or blocking a waterway, and see what impact it has on the results.
The definition of a flood simulation scenario is stored in a simulation layer and is listed in a new category in the Contents pane for the scene. A scene can contain multiple simulation layers but only one can be active at a time. A simulation layer can include the following:
- A defined area of interest. This is required.
- The rainfall rate through time, which can change over time.
- The analysis processing cell size, which can be adjusted to control the resolution of the scenario.
- Ground infiltration rates, which can be set using either a raster or a flat value across the entire area of interest.
- Surface roughness values, which impact water flow speed.
- Water sources from points and areas.
- Water flow barriers and channels.
- Water sink areas
- The starting water level, which can be set using a raster.
When a flood simulation scenario is run, the simulation layer’s area of interest is sampled to generate an elevation surface raster at the analysis processing cell size. By default, all visible elements in the scene—such as the ground surface, buildings, and dam walls—are included in the creation of this elevation surface. Consequently, it will take longer to sample scenes with more content. This elevation surface raster is sent to the graphics processing unit (GPU), where water is added to each cell, for example through rainfall, and shallow water equations move that water over the surface.
Dive-in:
For more information on the mathematical assumptions and limitations involved when performing flood simulation, see the Esri technical paper on this subject.
After each iteration of calculations is completed, the updated distribution of the water is rendered on top of the content in the 3D view. The level of detail used for the simulation analysis is used to lock a matching level of detail for the underlying ground surface. You can pause and continue to play the simulation using the playback controls and interactively navigate within the scene while it is running.
The simulation layer’s symbology defines which property—water flow rate (in cubic meters per second), water depth (in meters), or water speed (in meters per second)—is used to colorize the display of the water, which is rendered as a display shader in the 3D view.