Spring Harbor Watershed Modeling

In 2018, the City of Madison experienced two devastating storms that led to widespread flooding, disrupting communities, and damaging infrastructure. In response, the City launched a comprehensive watershed study program to better understand the causes of flooding and develop long-term solutions to reduce future flood risks. One of the first areas studied was the Spring Harbor watershed, where detailed modeling began in 2019.

Since the initial study, conditions in the watershed have changed, requiring an update to the flood models and a reassessment of the selected mitigation strategies. In 2023, Carollo joined the effort, providing planning, modeling expertise, quality control, and oversight to refine the City’s approach. The goal was to develop solutions that not only reduce flooding but also integrate seamlessly into the city’s existing infrastructure and stormwater management strategy. By optimizing each approach within a sophisticated computer model, Carollo helped identify improvements that maximize flood mitigation while remaining practical to implement.

The project relied on advanced two-dimensional modeling software, which provided a highly accurate representation of surface flooding. This technology also allowed for the creation of detailed graphical results, helping city officials and community members visualize the impact of different flood mitigation strategies.

Ultimately, the study produced two sets of solutions. The first, an “idealized” solution set, outlines the most effective long-term flood mitigation strategies needed to meet all of the City’s flood reduction targets. However, due to the scale and cost of these measures, full implementation would take decades. Recognizing the need for more immediate action, the project team also developed a “near-term” solution set. These measures focus on providing relief in the most vulnerable areas while laying the groundwork for the City’s long-term flood resilience.

Currently, the near-term solutions are in the design phase, marking an important step toward a more flood-resilient Madison. By combining cutting-edge modeling with practical, buildable solutions, Carollo helped the City create a clear, defensible plan to mitigate flooding and protect the community for years to come.