The Flood Impact Analysis solution delivers a set of capabilities that helps you develop localized flooding scenarios and visualize the impact of flooding on public infrastructure and critical facilities.
In this topic, you will learn how to use the solution by assuming the role of a user and performing the following workflows.
Note:
Use your organization's data or the provided sample data to complete the tasks included in this solution's ArcGIS Pro project.Get started
First, you will download and unzip the Flood Impact Analysis ArcGIS Pro project.
- Sign in to your ArcGIS organization and browse to the Flood Impact Analysis item.
- From the item page, click Download.
- Unzip the downloaded folder, and then from the unzipped folder, open the ArcGIS Pro project.
- In the Catalog pane, expand the Tasks folder.
Note:
If you do not see the Catalog pane, from the View tab, in the Windows group, click Catalog Pane.
- Expand the Tasks folder, and then double-click the Flood Impact Analysis task item to open the Tasks pane.
Getting to know Flood Impact Analysis
Next, you will assume the role of a GIS Analyst responsible for analyzing the potential flood impact for your community and sharing the results with emergency management, public works, and planning agencies. The Flood Impact Analysis ArcGIS Pro project includes a series of tasks to help guide you through these workflows.
Understand Flood Impact Analysis
Flood Impact Analysis supports a series of workflows that streamline the process of developing flooding scenarios to help plan for a flood event. These workflows include preparing the data for analysis; defining the flood impact area and the impact on infrastructure, facilities, and buildings; sharing the flood impact information; visualizing the flood impact in 3D; and sharing the impact in 3D.
The Understand Flood Impact Analysis task will introduce you to the capabilities of the solution, the data requirements needed to analyze flood impact, and how to visualize flood scenarios in 3D.
- In the Tasks pane, expand the Getting to Know Flood Impact Analysis task group to see the collection of tasks.
- Double-click the Understand Flood Impact Analysis task name and follow the steps.
Download sample data
Optionally, the Download Sample Data task includes a link to sample data that you can use to help you learn how to use the tasks and organize your data.
In the Tasks pane, double-click the Download Sample Data task name and follow the steps.
Prepare data
Accurate analysis and visualization of the flood impact will depend on several factors, such as availability of flood depth data in the form of rasters, ground elevation data such as a Digital Terrain Model (DTM) or lidar, and features describing the assets to be analyzed such as roads, bridges, and buildings. The data preparation workflow includes a series of tasks to help prepare the data for analysis.
Tip:
In ArcGIS Pro, click a task name to view its description at the bottom of the Tasks pane.Verify projected coordinate systems
The Verify Projected Coordinate Systems task allows you confirm that all data being used in the analysis is in the same projected coordinate system.
In the Tasks pane, double-click the Verify Projected Coordinate Systems task name and follow the steps.
Prepare flood depth rasters
The Prepare Flood Depth Rasters task allows you to remove negative values, extract flooded areas, and create the flood depth geodatabase.
The risk value for each raster is read from the riskTypeTable for the chosen risk type. You can find the riskTypeTable in the FloodImpactAnalysis.gdb. You can use the existing risk types, modify them, or you can add another entry.
In the Tasks pane, double-click the Prepare Flood Depth Rasters task name and follow the steps.
Prepare water surface elevation rasters
The Prepare Water Surface Elevation Rasters task allows you to create a water surface elevation raster, extract flooded areas, and create the water surface elevation input geodatabase.
In the Tasks pane, double-click the Prepare Water Surface Elevation Rasters task name and follow the steps.
Define flood impact
Effective flood response planning begins with a better understanding of the potential flood impact. This task group is designed to step through a standardized process to create and analyze the impact of each flood scenario on your community. A flood scenario can be defined in the risk type table as a percent chance of flooding, historical average such as 100 year, or number of feet above normal.
Create flood impact areas
The flood impact area defines the geographic extent for each flood depth scenario. The flood depth data prepared in the Prepare Data task group will be used to create the flood impact area. These flood impact areas will be the foundation for analyzing impact to buildings, roads, or bridges in each of the subsequent tasks.
In the Tasks pane, double-click the Create Flood Impact Areas task name and follow the steps.
Analyze roads
This task allows you to analyze impacted roads by calculating depth of flooding for each road segment for any number of flood levels. The flooded roads can be an impediment to successful evacuations for first responders and community members when it is unknown which roads will be impacted. You can also symbolize the impacted roads for each flood impact area. The result will be a new feature class representing road segments with a depth attribute for each flood scenario.
In the Tasks pane, double-click the Analyze Roads task name and follow the steps.
Analyze low-level water crossings
This task allows you to calculate depth of flooding for each low-level water crossing for each flood scenario. The result can be used to identify watch points for observers to report flood depth during the flooding event. The parameters for this step are similar to the road flood depth except for the buffer distance. If this distance is specified to be greater than zero, the analysis will run against the buffered input features. This parameter helps you find points within the buffer distance that have been misplaced. You can then symbolize the low-level water crossings by flood depth.
In the Tasks pane, double-click the Analyze Low-Level Water Crossings task name and follow the steps.
Analyze bridges
Use this task to calculate the bridge height above flood water surface for each flood scenario. Some bridges may have one side that is lower than the other. The bridge geometry is needed to calculate the height above the water surface instead of a single point along the bridge. Therefore, the bridge data needs to be a 3D polygon feature instead of a 2D feature. This task will extract bridge surfaces from a lidar point cloud as 3D polygons, so they can be used in the next task to determine the height above flood level.
Note:
This task requires lidar point data stored in a LAS dataset . The bridge surfaces must have a separate class code in the LAS dataset.
Note:
This task requires that you have a water surface elevation (WSE) geodatabase as described in the Prepare Data task.
Tip:
The result of this task is a new point feature with the minimum height above water surface for each water level in the WSE geodatabase. You can label the point with the minimum height attribute value to show how much clearance there will be below the bridge or how deep the water will be over the bridge if the height above water has a negative value.
In the Tasks pane, double-click the Analyze Bridges task name and follow the steps.
Analyze buildings
Understanding building exposure to flooding can help response personnel prioritize evacuations and stage equipment where it can be used effectively. It can also help mitigation planners understand buildings that are good candidates for purchase and removal. Use this task to calculate flood exposure on building polygons or 3D building multipatch feature layers. The tool will use your water depth geodatabase and the specified risk type to calculate the flood depth exposure to each building within the flood impact area. You can then symbolize the features according to the calculated flood exposure attribute such as the flood depth. Using a graduated color ramp will allow you to illustrate the severity of the building exposure.
In the Tasks pane, double-click the Analyze Buildings task name and follow the steps.
Share flood impact information (optional)
After the analysis is completed, you can share the results with community stakeholders who can use the information to begin flood response or mitigation planning. Use this task to choose which flood impact layers to share, such as the flood impact area, impacted roads, bridges, and buildings for each flood scenario. Share the results for each flood scenario.
In the Tasks pane, double-click the Share Flood Impact Information task name and follow the steps.
Visualize flood scenarios in 3D (optional)
The best way to communicate the impact of a flood scenario is to show how it will impact homes, streets, bridges, and neighborhoods. Visualizing the flood scenario in a 3D scene is a compelling way to communicate the potential flood impact in your community.
Show flood impact map in 3D
This task allows you to convert the map containing the results of the flood impact analysis to a 3D scene using 3D symbology and scene elevation. A digital terrain model (DTM) raster can be added to the 3D scene to provide a realistic scene for illustrating the impact of the flood.
In the Tasks pane, double-click the Show Flood Impact Map in 3D task name and follow the steps.
Create 3D flood levels from raster
This task allows you to create 3D flood levels from raster input data. The result is a 3D version of the 2D raster data. For example, you may want to show a flood impact area at 5 feet against a building to illustrate the depth of flood on the building.
In the Tasks pane, double-click the Create 3D Flood Levels From Raster task name and follow the steps.
Source 3D content
Visualization of 3D flood levels is more powerful when shown together with other 3D layers to complement your flood impact map. If you do not have 3D content readily available, you can leverage 3D content and basemaps available in ArcGIS Online or ArcGIS Enterprise. Alternatively, you can use the 3D Buildings solution to create your own 3D experience visualizing the built environment and elevation surfaces in your community.
In the Tasks pane, double-click the Source 3D Content task name and follow the steps.
Create depth elevation raster
A depth elevation raster can improve the visualization of flood impact in 3D scenes, particularly in flood scenarios with very shallow flooding. Use the Create Depth Elevation Raster task to create the depth elevation raster. You can repeat this task for every water surface elevation (WSE) raster.
In the Tasks pane, double-click the Visualize Flooding Scenarios in 3D task name and follow the steps.
Share a 3D flood impact scene (optional)
After the task to visualize 3D flood scenarios is completed, you can publish a 3D web scene for your flood impact scenarios. The 3D web scene can be shared with stakeholders who are responsible for flood response planning and flood mitigation planning.
Note:
These tasks require ArcGIS Online or ArcGIS Enterprise 10.5 or later.
Project ground elevation surface
Complete this task only if you want to use the published ground elevation layer in a global web scene.
In the Tasks pane, double-click the Project Ground Elevation Surface task name and follow the steps.
Publish 3D flood impact scene
Complete this task to set the coordinate system and publish the new 3D scene to ArcGIS Online or your organization.
In the Tasks pane, double-click the Publish 3D Flood Impact Scene task name and follow the steps.
Share depth elevation raster
Complete this task to share the depth elevation raster that was created previously to help improve the visualization of the 3D scene.
In the Tasks pane, double-click the Share Depth Elevation Raster task name and follow the steps.
After you have shared the 3D scene and depth elevation raster, you can view the results of the Flood Impact Analysis in a Scene Viewer in ArcGIS Online or ArcGIS Enterprise. Share the scene with your colleagues to help them understand the impact of local flooding on your community.