Connectivity in urbanscapes can cause unintended flood impacts from stormwater systems

Urban flooding is intensifying worldwide, presenting growing challenges to urban communities. We posit that most of the flood management solutions currently employed are local in nature and fail to account for ways in which the space–time connectivity of floods is exacerbated by built infrastructure. We examine the 2014 flood in Southeast Michigan to identify key factors contributing to urban flooding and explore the implications of design choices on inundation. Findings reveal that stormwater infrastructure that neglects flood spatial connectivity can be ineffective in mitigating floods, leading to inundation even in the absence of local rainfall. Different configurations of network connections—including interfaces with natural channels—can significantly impact upstream surcharge, overflowing manholes and inundation conditions. These results emphasize the need to consider interconnectedness of flood processes in urban watershed systems to mitigate limitations inherent in the design of flood control and warning systems, to enhance urban flood resilience.