Developing flash-flood resilience in areas with buried streams and shallow groundwater: Improving stormwater design guidance and community understanding through science and ethnography
High-intensity rain events are increasing, often exceeding the pipe capacity, and resulting in flooding of streets and houses. In older towns, this pipe capacity also may be reduced because streams were buried in pipes and land development created compaction layers in the soil. These compaction layers reduce deep infiltration, resulting in shallow groundwater movement laterally into the pipes through leaky inlets, manholes, and pipes. These uncharacterized waters reduce that capacity at a time when it is most needed, resulting in flooding. This flooding greatly impacts the residents psychologically and financially, yet the damage may not be sufficient to trigger disaster declarations and governmental financial support and insurance payouts. Middletown’s Bloody Run sewershed will be a demonstration case for combining engineering and ethnography to improve our understanding of stormwater flow, buried streams, and shallow groundwater in an older, fully developed community subject to pluvial flooding. Pipe flow and soil water movement will be measured continuously. Infiltration and compaction tests will be performed throughout the sewershed to assess the surface infiltration rates and soil compaction. These data will be used to calibrate an existing SWMM model of the system. This model will then be used to run scenarios based on downscaled climate models. Resident interviews will capture the stories of flooding and perceptions of changing storm patterns or land uses. It also will provide an assessment of impacts in terms of personal, familial, and community hardship and of strategies for coping and recovery. This will result in a fuller understanding of how flooding affects historical memory, shared connection/understanding of place, and attitudes toward the natural environment. These results then can be used by Middletown and other locales to develop resiliency plans that address both their engineering challenges as well as the anticipated impacts on the residents of these pluvial floods.