This blog article was originally published on September 17, 2020, and has been updated. The last previous update was January 4, 2023.
In the news: Severe thunderstorms and heavy rain are expected across portions of the mid-Mississippi Valley into the Ohio Valley and portions of Arizona. Just a week ago, heavy rains hit Indiana, causing rivers to crest and setting water level records as roads and bridges were severely damaged or washed out entirely by the flood waters.
According to NOAA, flooding is the major threat for inland populations. Flash flooding can occur in the blink of an eye due to intense rainfall, often accumulating from some distance away. Flooding along rivers and streams can last for many days after a storm has passed.
Make a flood map
ArcGIS Living Atlas of the World includes authoritative live feeds and other content that helps you learn more about current and predicted flood conditions. Follow these steps to make your own flood map in a minute (or less) using Living Atlas content.
Step 1 — Sign in to your ArcGIS account and open Map Viewer. There are two ways to add layers from the Content (dark) toolbar:
(1) Click Add, then Browse layers.
or (2) Click Layers, then Add.
Step 2 — Choose Living Atlas from the Add layer drop-down.
Step 3 — Enter “stream gauges” in search to locate matching layers from Living Atlas. Scroll down to locate the Live Stream Gauges layer and click [+ Add] to add it to the map.
Tip: To learn more about any layer, click the layer card to view the item summary or description.
From the Live Stream Gauges item overview we learn that the layer shows near real-time stream gauge readings compiled from a variety of sources. The layer is updated hourly. Once added to the map, the legend shows the current flood status.
To simplify the map and focus on stream gauges showing flood conditions, a filter can be applied.
Step 4 — Ensure that the Live Stream Gauges layer is selected, then click Filter in the Settings (light) toolbar on the right. Note there is an existing expression that filters for gauges with recent updates.
Click Add new.
Step 5 — Construct a filter expression as follows:
a – Select Status as the attribute from the list.
b – Select includes as the operator from the dropdown list.
c – Click Select values.
d – Select the desired values from the drop-down list. In this case we want to focus on minor, major, and moderate flood status. When finished your selections, click Done.
Step 6 — The new filter should look like the one shown below. Click Save.
The map shown below is the result of applying the following expression: Current Status includes Minor Flood, Major Flood, Moderate Flood. Click any gauge to view its pop-up for more information.
Step 7 — Return to Add layer from Living Atlas and search using the string “water forecast.” Scroll down to locate the National Water Model Maximum Flow (10 Day Forecast) layer. Click [+Add] to add it to the map.
From the National Water Model Maximum Flow (10 Day Forecast) item details we learn that the layer presents a summarization from the National Water Model 10-Day forecast, including maximum flow per river segment and the day and time of maximum flow for the contiguous United States.
Step 8 — Adjust the layer order to draw the gauges on top of the river and stream segments.
In Layers on the Contents (dark) toolbar, grab the Live Stream Gauges layer and drag it above the National Water Model layer.
Click any river or stream segment to display the pop-up with more information.
In a minute or so with just a few clicks, a map showing current flood conditions and 10-day forecast summaries has been authored.
Improve your map
Experiment with different basemaps to see which you like best. You can alter layer transparency and symbols to emphasize the content you want. Add other related layers from Living Atlas to add additional context.
More information
For more information, see the following:
- Configure time settings (Help)
- View time maps (Help)
- ArcGIS Living Atlas website
- ArcGIS Living Atlas earth observations content
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