Concurrent Session: Hydrologic assessment in flood-prone landscapes
10:40 AM - 12:00 PM Wed
TITLE: Connecting flood-related fluvial erosion with vulnerable downstream road-stream crossings
ABSTRACT: Fluvial erosion is increasingly responsible for infrastructure and building damages associated with floods across the U.S.. Northern Wisconsin is no exception: extreme floods in 2016 and 2018 caused widespread culvert blockages and road failures, including extensive damage along steep tributaries and ravines in the Marengo River watershed. In 2019, a pilot study was begun with partners from the U.S. Geological Survey, Wisconsin Wetlands Association, Ashland County, and the Northwest WI Regional Planning Commission to characterize the connections among the loss of wetland storage, headwater drainage extension, and downstream fluvial erosion hazards (FEHs). This study used a GIS approach to classify channel segments into fluvial process zones (FPZs) based on Strahler stream order, specific stream power, channel slope, presence of adjacent steep valley sides and headwater flats, and adjacent soils and surficial geology. The resulting vulnerability maps provide a screening framework to identify FPZs that are most sensitive to incision, gullying, and mass wasting along steep headwater channels, as well as potential lateral migration, mass wasting, and coarse sediment deposition along the valley bottoms of perennial streams. Additionally, each FPZ was characterized in terms of potential hydrologic alteration associated with ditching. The vulnerability mapping products and rankings of sensitivity of FPZs to large floods will ultimately be used by Ashland County and their collaborators to prioritize natural flood management projects that mitigate FEHs, restore hydrology, and reconnect streams, floodplains, and wetlands.
BIO: Dr. Faith Fitzpatrick is a research hydrologist at the U.S. Geological Survey in Madison, Wisconsin. Over her 30+ year career, she has worked on fluvial geomorphology-related studies of river channel change and floods, river corridor sources and sinks of sediment and phosphorus, habitat in urban streams, oil spills, river restoration, and hydrodynamics of Great Lakes estuaries.