Ongoing
Projects

The Global Continental Palaeohydrology (GLOPOCH) working group aims to study "Palaeo-Hydrology: Ancient Disasters employing Modern Application (PHADMA)." This broad focus allows for research into a wide range of hydrological events throughout history, aiming to apply this knowledge to modern challenges. The GLOCOPH initiative is supported by funding from the International Union for Quaternary Research (INQUA) and will be continued by Ankit Agarwal (IIT Roorkee), Ray Lombardi (Univ. Memphis), and Willem Toonen (Vrije Universiteit Amsterdam) for the next four years.

The main goals of the current 4-year INQUA working group application are to increase our knowledge of the global spatial and temporal distribution of past hydrological extremes, to improve the quality of modern flood event attribution, and to stimulate the transfer of knowledge.

The Tennessee River Gorge is a narrow and turbulent reach of the large river, which poses a significant risk of back flooding in Chattanooga, Tennessee. A recent U.S. Geological Survey study reported geologic evidence of a megaflood approximately 375 years ago. When adjusted for the river basin's scale, the estimated size of this megaflood is unprecedented in the southern Appalachian region and ranks among the most extreme floods recorded in the United States. If such a megaflood were to occur today, it would constitute a catastrophic risk to the people and infrastructure in the Tennessee River Valley. Therefore, it is critical to investigate megaflood mechanisms by exploring multiple hypotheses that could explain the patterns of flood deposits found in the gorge to increase resilience to such an unprecedented flood hazard.

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This project, funded by Tennesse Valley Authority Research and Innovation, explores one hypothesis that local changes in water levels caused by a landslide could explain river sediment deposition at high elevations in the valley. The Tennessee River Gorge has steep slopes and few floodplains, with many landslides showing its history of hillslope failures. Sometimes, large landslides can block the river, creating temporary dams. When these natural dams fail, they release water rapidly, causing what's known as a landslide-lake outburst flood. The study approach evaluates the feasibility of this alternative hypothesis by 1) surveying and estimating the age of a large landslide within the Tennessee River gorge that is directly upstream of the paleoflood deposit and 2) performing a hydraulic dam-break analysis to simulate flows to compare to paleoflood stages.

The Missouri River Basin is prone to both water deficit and surplus, leading to catastrophic and potentially compounding hydrologic hazards. Over the past 50 years, the region experienced more frequent shifts between very dry and very wet conditions (precipitation whiplash events) due to regional warming, a trend likely to continue under future climate change. The downstream impacts of precipitation volatility on flood discharge are not yet known. Understanding flood response to precipitation whiplash events is crucial in predicting future changes to flood hazards and informing water management decisions in river basins dealing with droughts and floods in quick succession.

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Our team addresses this knowledge gap using tree-ring precipitation and sediment-based paleoflood records. 

My collaborators at The University of Alabama (Matthew Gage and Dr. Lisa Davis) and I reconstructed several paleoflood records on the Tennessee, Clinch, French Broad, and Ocoee rivers. The goal of this project, funded by the USGS 104g program and Tennessee Valley Authority, is to update flood frequency curves with paleoflood data and refine flood risk in cities with wastewater treatment plants serving the broader Tennessee communities.