Research map showing vulnerability of Wisconsin landtype associations to increased flood flows

Areas with landform characteristics that lead to more rapid runoff are expected to be more vulnerable to increases in flood flows from more intense rainfall in the future. Those characteristics include fine-grained soils, low storage in terms of lakes and wetland, steep slopes, and high drainage densities. Landform characteristics that attenuate runoff include coarse-grained soils, high storage, gentle terrain, and low drainage densities. Groundwater recharge tends to be a dominant hydrologic process in such areas which are expected to be more resilient to increases in future flood flows. Landtype associations (LTAs) are ecological units that relate closely with characteristics affecting runoff. A case study from the July 2016 northwest Wisconsin flood regarding the design of flood resilient road-stream crossings used LTAs to classify the vulnerability of landforms in Wisconsin to increases in flood flows. Each LTA was classified as either vulnerable, moderately vulnerable, moderately resilient, or resilient based on their characteristics and results from the case study. The classification relied on professional judgement guided by the drainage density and storage for each LTA while considering the flood flows observed at nearby U.S. Geological Survey gaging stations. This data publication contains the LTA vulnerability classifications as a geodatabase and shapefile. Identifying areas that are more vulnerable or resilient to future flood flow increases will help planners and project designers improve the flood resilience of road-stream crossings.
These data will help project designers accurately determine the vulnerability class for their project watersheds and whether to consider adjustments to the classification. These data also contain the drainage density (miles/square mile) and percent storage for each LTA.
For more information about this study and these data, see Higgins et al. (in press).