Flood Impact Analysis FAQ

This FAQ section provides answers to commonly asked questions about this solution.

Which type of flooding scenarios can be analyzed?

Flood Impact Analysis can be used to develop flooding scenarios for several flood risk types, including riverine, storm surge, tidal surge, and sea level rise scenarios at multiple flood depths or stages.

What type of data is required?

Accurate flood impact analysis and visualization relies on several factors, including the availability of flood depth data (in raster form), ground elevation data, and assets such as roads, bridges, and buildings. Water Surface Elevation is optional. The Flood Impact Analysis solution includes a series of ArcGIS Pro tasks to help you prepare your data for analysis. You can learn more by reading the FEMA guidance for risk mapping, assessment, and planning.

Where do I get elevation data?

Bare earth elevation data can be sourced from a Digital Elevation Model (DEM) or Digital Terrain Model (DTM). Both DEM or DTM data can be derived from lidar or photogrammetry. You can learn more by visiting the USGS's website for elevation data and mapping.

Where do I get flood depth data?

Flood depth data is typically derived from hydrological studies done on a specific area using elevation data. It can be sourced from national agencies such as FEMA, NOAA, flood model consultants, or hydrological engineering firms. If you do not have flood depth data, you can use tools like Arc Hydro, but please note this is to help provide a visual and does not replace an official hydrological study. To learn more, see the Creating Flood Depth Rasters for the Flood Impact Analysis Solution blog.

Where do I get water surface elevation data?

Water Surface Elevation (WSE) data can be acquired from flood model consultants, hydrological engineering firms, or Arc Hydro. If customers do not have WSE data, the data can be derived from the elevation data and flood depth data used in the Flood Impact Analysis solution. The WSE data is optional in the solution for 2D analysis but required to visualize the flood impact in 3D.

What infrastructure data is required in the Flood Impact Analysis solution?

Flood Impact Analysis requires asset and infrastructure layers such as roads, bridges, buildings, and low-level water crossings to support analysis.

Can I analyze other types of infrastructure and asset data?

Yes, you can use the tasks in the solution to analyze other types of infrastructure and asset data, as long as the data being analyzed is in the same coordinate system. The Analyze Roads task can assess other line features, the Analyze Buildings task can assess other polygon features and raster datasets, and the Analyze Low-Level Water Crossings task can assess other point features.

Can I use Flood Insurance Rate Maps (FIRMS) instead?

No, the current Flood Insurance Rate Maps (FIRMS) do not provide the spatial accuracy to determine which assets, infrastructure, and populations will be impacted at various flood depths. Moreover, they do not provide a way to determine the degree of impact for flood scenarios before a flood hits the local community.

What’s the difference between the Flood Impact Analysis solution, Arc Hydro, and the Flood Simulation tools in ArcGIS Pro?

These workflows can function independently or together. The Flood Impact Analysis solution helps you develop localized flooding scenarios and visualize the impact of flooding on public infrastructure and critical facilities. Arc Hydro can be used to derive flood extents or flood impact area, water surface elevation (WSE), and depth of flooding for a river that can be used in the Flood Impact Analysis solution. The Flood Simulation tools in ArcGIS Pro take visualizations another step further to help you understand water movement within a specific area in 3D. To learn more, see the Understand flooding using ArcGIS Pro blog.

Can I visualize flood impact to my community in 3D?

Yes, the Flood Impact Analysis solution supports the visualization of flood impact to a community in 3D. It is an optional workflow in the solution.