15 Terrestrial records of hydroclimate variability from the Pleistocene through the Common Era

Landscapes respond to climatic variability, extreme hydrologic events, and long-term environmental change, informing water resource management. We invite terrestrial proxies of hydroclimate from perspectives in paleoclimatology, geomorphology, or hydrology. Submissions from early-career scientists are encouraged.

Monday, 9 March 2026
1:30 PM - 3:30 PM
RCC, 105

Contrasting Hydroclimatic Controls on Flooding Across Large and Small Midwestern Watersheds

Paper number: 15-6
Program: Technical Sessions
Time: 2:50 PM – 3:05 PM

Authors

Abstract

Understanding how fluvial systems of different scales respond to climate and land use variability is essential for assessing past floodplain evolution and future flood risks. We reconstructed Late Holocene flood frequencies from sediment records recovered from floodplain lakes in two contrasting Midwestern watersheds: the large Ohio River Basin (~500,000 km²) and the much smaller White River Basin (~29,000 km²). Along the Ohio River, paleoflood proxies from three oxbow lakes reflect reduced flooding during the Medieval Climate Anomaly (MCA; 950–1250 CE), linked to southerly, clockwise atmospheric circulation that promoted intense warm-season rainfall and reduced winter snowpack (-PNA-like conditions). In contrast, flooding increased during the Little Ice Age (LIA; 1400–1800 CE) due to enhanced northerly atmospheric flow and increased snowfall (+PNA-like conditions), and the watershed-scale integration of spring meltwater. The White River record showed an antiphased response: increased flooding during the MCA and reduced flooding during the LIA. This pattern suggests that, during the preindustrial Late Holocene, smaller watersheds were more responsive to discrete, intense rainfall events, while large watersheds were more sensitive to widespread spring snowmelt. Both rivers exhibited increased flooding during the Current Warm Period, likely due to Euro-American land-use changes that decoupled natural climate-flood relationships. These results highlight that watershed size is an important control on fluvial sensitivity to seasonal hydroclimatic drivers and that anthropogenic land use now amplifies flood risk irrespective of prevailing atmospheric circulation. Understanding these scale-dependent dynamics is critical for refining paleoflood reconstructions and anticipating future fluvial behavior under continued climate and land-use changes.

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411798

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