RAPID/Collaborative Research: Geotechnical and Geoenvironmental Properties of the Ahr Valley and Their Role in Structural Damage During Recent Flooding

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This Grant for Rapid Response Research (RAPID) award will focus on collecting and processing high resolution, perishable data on the spatial distribution of erosive and depositional patterns in the vicinity of infrastructure and river sections that were affected during the 2021 Western European Floods. These data will be interrogated to provide insight into how channel geometry, flow conditions, the presence of debris, and geotechnical properties affect performance of engineered structures interacting with extreme floods. This is relevant in the context of global climate change where extreme flooding is expected to occur more frequently and at larger magnitudes. Many of the modern structures that were damaged during the flooding in Germany are similar to structures found across the United States and knowledge gained from studying this flooding event will be transferable to the built environment in the United States. Data generated during the project can provide support to update infrastructure design and flood mitigation strategies to meet future demands intensified by climate change.The specific goal of this research is to provide new data and knowledge on the impact of extreme flooding events on infrastructure and the effects of urban land usage and environmental conditions. Through this data collection, a detailed set of case studies that document sediment dynamics in the vicinity of infrastructure and in urban river sections will facilitate identification of features and processes that potentially influence performance of engineered structures during extreme flooding. Geophysical field measurements in the riverbed will include rotary side scan sonar, high resolution chirp sonar, and single beam sonar. This will enable collection of channel bathymetry and sediment stratigraphy, which may reveal novel information on if or how changes in substrata in the upper meter of the river bed play a significant role in sediment mobilization and instability during extreme hydraulic events. Both ground-based and airborne LiDAR surveys will provide high-resolution, 3D models of the riverbanks and surrounding structures, enabling assessment of potential interaction between erosive patterns and structural damage. Multispectral images will be collected using drone-based technology to identify broader erosive and depositional patterns. Geotechnical field measurements will include pocket free fall penetrometer, pocket erodometer, field vane shear, and field fall cone measurements in addition to sample collection for laboratory measurements. The geotechnical observations, coupled with the geophysical and remote sensing data, will enable a comprehensive assessment of how sediments were eroded and transported near engineered structures.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.