A new study centered on the Italian city of Como outlines a flood-defense concept called Swarm Flood Proofing, which coordinates many small temporary and permanent protective measures across an entire urban area rather than relying on a single large barrier. The research, developed within the Italy-Switzerland Interreg-funded GESTI.S.CO. project, is published as an accepted manuscript in the journal City, Territory and Architecture.
How the swarm concept works
The approach, conceived by a research team led by Daniele Fabrizio Bignami with co-authors Emanuele Carenzo, Martina Conti and Laura Raspanti, combines microscale flood-proofing techniques, such as temporary barriers and small permanent structural fixes, and coordinates them citywide instead of applying them only to isolated buildings or neighborhoods. The authors describe existing small-scale flood-proofing efforts as typically fragmented or improvised. Their proposal aims to link these scattered measures into a cooperative network capable of protecting a built environment as a whole.
Why Como was chosen as a test case
Como faces a layered flood risk: water can rise simultaneously from Lake Como and from surrounding hillside runoff. The city has pursued a large-scale flood infrastructure project for more than thirty-eight years without completion, a timeline the study cites as evidence of how difficult major engineered defenses can be to deliver in dense, historic urban settings. According to the study's abstract, the swarm approach modeled for Como showed potential to address both the upstream and lake-driven flood threats through widespread, cooperative use of small-scale measures.
A simulation, not a finished solution
The authors are explicit that this is a design simulation intended as a strategic option to weigh against other flood-control paths, including non-structural measures, major structural infrastructure and green infrastructure. It is not a tested or completed defense system. They argue the swarm model is most useful where large infrastructure or purely non-structural approaches are hard to implement because of cost, cultural heritage protections, high building density or competing land-use and environmental priorities.
Conditions and limits noted by the authors
The researchers state that applying this approach to other vulnerable cities would depend on verified local conditions and detailed hazard and risk analysis specific to each context, not on treating the Como case as a universal template. They also frame the concept in governance terms, suggesting it could help planners and civil protection officials build disaster-resilient communities through distributed, cooperative involvement in flood defense. Because the paper is currently published as an accepted manuscript, the reported results remain subject to further editing before a final version is released, even as the core framework, coordinating many small measures at city scale, stands as the study's central contribution.