Climate Ready Boston
The City of Davenport, Iowa, experienced record flooding in 2019 when the Mississippi River flooded the city’s riverfront for 103 days of the year and reached a new record crest. The long-term detours, drains on city resources, and lack of access to the riverfront’s many public spaces galvanized the desire to create a long term Mississippi River Flood Resiliency Plan for Davenport’s beautiful 9-mile riverfront.
Together with engineering partners HR Green and Shive Hattery, Sasaki collaborated with the Davenport Public Works team and the community to develop a Resiliency Plan that identifies a mix of built structure and other solutions for flood mitigation.
The benefits of the plan, once implemented, will be transformational for Davenport. For example, if the plan’s recommendations had been in place since the year 2000, they would have greatly reduced or eliminated the city’s flood response activities for over 850 days in the Garden Addition neighborhood.
The Resilience Plan includes a combination of non-structural approaches (like land use changes) and structural solutions (like riverfront berms, floodgates, or infrastructure approaches) that addresses both the immediate needs and prepares Davenport for larger flood events in the future.
The plan charts out three phases. Phase 1, also known as the “fix what’s broken and prepare for the future” phase, includes projects that offer an immediate return on investment in the form of increased resilience during low to moderate flood stages. Phase 2 outlines structural solutions that offer continuous protection along the river against flooding up to flood stage 22 (in the past 20 years, flooding has reached stage 22 for 7 days). Once completed, these solutions will provide reliable, permanent protection that requires far less emergency deployment in flood conditions. The final phase involves the replacement of temporary pump stations with permanent ones along the riverfront, which will improve response times and roadway access during flood events.
Each stage of the planning process asked Davenport residents to express their ideas, based on their knowledge of their city and of the previous flood impacts. The emerging themes from the community and stakeholder feedback helped define the plan’s four guiding principles, which articulate the overarching values and goals that apply to all of the concepts included in the Resiliency Plan:
In addition to overarching priorities, the community also guided the team’s understanding of what types of flood mitigation solutions would be right for Davenport. Residents’ priorities were rooted in the collective love for the riverfront as a key part of the city’s identity, as well as the recent first-hand experience of the challenges of a flood event.
There was strong desire for solutions that were permanent or required lower maintenance, so that they could be reliable for the long term, without requiring deployment during the dangerous conditions of a flood event. When asked about what the solution could look like, most participants desired to see a landscape approach (as opposed to a flood wall) to maintain and bolster the riverfront as a beautiful public space for the city.
To respond to the importance of both flood mitigation and the riverfront as a public space, the plan incorporates ideas that provide community benefits in addition to flood resilience. In the open space closest to Downtown Davenport, for example, the plan recommends the integration of a berm within an elevated plaza, to maintain views of the water and remain accessible during flooded conditions.