Flooding

The City of Madison Engineering Division launched its Watershed Study Program in January 2019. During the studies, Engineers will review the existing stormwater system to determine the causes of flooding and then develop projects to reduce the risk of flooding. This is a continued effort to address areas hardest hit by flooding in August 2018 and to create a more resilient stormwater system. 

The map shows the study areas in progress or complete.


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A watershed is an area of land that drains to the same point.  It can be as small as the part of your roof that drains to one downspout to as large as all the land in North America that drains to the Mississippi River in the Gulf of Mexico.  

Watershed Study Phases

Each Watershed Study has three phases.  There is a public information meeting following each phase to share the information and get feedback.

1. The first phase is to collect all the available information about stormwater in the watershed.  Information includes the sizes and types of storm sewer pipes, the sizes and vegetation in the open channels and ditches, where the buildings and other impervious areas are, and where there has been flooding before.
2. During the second phase, the computer models of the stormwater system are built.  The models have information about the stormwater system (pipes, structures, ponds, greenways) and the ground and buildings above the stormwater system. Rain can fall in very different ways.  Different storms are run through the computer models to see where flooding occurs.  The storms range in size from small (storms that occur often) to very large (like the storm in August 2018). Also, during the watershed studies, the City used equipment to measure the rain and how deep stormwater was in the pipes and channels.  The information from the monitoring equipment was then used to fine-tune the computer models.  The computer models were adjusted so that the computer model results more-closely matched the information from the monitoring equipment.
3. During the third phase, solutions are developed to reduce the flooding that occurs.

The map shows the study areas in progress or complete.  You can click on the map and go to the specific watershed study page to see the progress on that watershed.

To learn more about why flash flooding occurs, what a watershed study entails, and the City’s ongoing plan to build flooding resilience, please visit the Flash Flooding Resilience page. *Note: Please view the story map using Firefox or Google Chrome browsers. Story maps are not viewable with Internet Explorer.

Learn more about the Watershed Studies.