EAR-PF: Impact of flooding intensity on levee development and dynamics

点击翻译按钮获取中文摘要

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Dr. Eric Barefoot has been granted an NSF EAR Postdoctoral Fellowship to carry out research and education plans at Indiana University. Dr. Barefoot will study flooding, a significant natural hazard that threatens critical infrastructure and communities in the US and across the world. Artificial embankments (or dikes) along river corridors are often constructed to reduce flooding hazards and these engineering projects often take advantage of natural levees on the floodplain. Levees form next to a river channel when the river floods and sediment spreads out away from the river. Because levee formation correlates poorly with river attributes, it remains challenging to predict where and when levees will form. This project seeks to test a new hypothesis: that the intensity of floods is a key control on levee formation. By combining analysis of floodplains across the State of Indiana with monitoring on the Lower Mississippi River, this project will determine the importance of flood intensity for levee formation. Dr. Barefoot will also identify processes by which sediment is transported on river floodplains during floods. These research outcomes will be coupled with an educational outreach plan that focuses on engaging public-school educators to produce new curriculum focused on flood hazards and sustainability in Indiana. Additionally, this project will bolster STEM engagement for LGBTQ+ undergraduate students through local field-based research opportunities. Natural levees form and develop during overbank flow, when sediment-laden water decants from the river, and deposits adjacent to the channel. The pattern of sediment deposition is controlled by water surface gradients across the inundated floodplain. The orientation and mag- nitude of water surface gradients are hypothesized to depend on flooding intensity; operationally defined here as the coefficient of variation of discharge (CVQ). However, the impact of flooding intensity on floodplain deposition is poorly constrained because direct observations of co-evolving floodplain topography and inundation hydraulics are scarce. This project will quantify the impact of flooding intensity on floodplain inundation patterns and analyze how resulting water surface gradients influence levee formation and development. This research will combine repeat lidar datasets with field surveys and sedimentological observations on floodplains in Indiana, USA, to compare levee morphology and composition spanning a range of historical flooding intensities. To link flooding intensity and sediment dispersal in a mechanistic framework, a complementary case study will be conducted in an end-member locality typified by low flooding intensity. In-situ measurements of water surface elevation and velocity during annual overbank conditions in an engineered section of the Mississippi River will be paired with repeat lidar topography surveys to couple inundation hydraulics with topographic evolution. New insights from this project will fill a critical research need because intensified flooding due to contemporary climate change threatens sustainability of river corridors. The scientific outcomes will inform land management strategies while also driving fundamental advances in sedimentology and geomorphology.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.