6/11: 9AM - 11AM, 231 TH (Trowbridge Hall)

Title: Assessing Historic and Modern Variability of Midwest Hydroclimate through Quercus Dendrochronological Reconstructions

Abstract: The United States Midwest is a key agricultural region which relies heavily on seasonal rainfall. Recent studies have shown an increase in precipitation but also concurrent droughts. To provide context and assess the magnitude of these shifts, an understanding of past and especially pre-instrumental hydroclimate is key. My research examines the relationship between regional Quercus (oak) tree rings and three climate variables: precipitation, vapor pressure deficit, and wet-day frequency. I developed three multi-century reconstructions for each May-July averages. I found an overall increase of regional moisture and an increase in their variability. Additionally, I reconstructed May-July runoff for the Des Moines River Basin and June-August runoff for the Cedar and Iowa River Basins. I found overall runoff has not changed in the last two centuries; however, there have been prolonged periods of droughts and pluvials. Overall my results indicate less stability in Midwestern hydroclimate with an increase in frequency of shifts from low to high years and vice versa. These findings have broader implications for a region highly sensitive to shifts in water supply, and states like Iowa should take these trends into consideration when developing water management strategies.