Indiana University-Purdue University Indianapolis (IUPUI) / Paleoclimate records from North and South America were used to develop a
holistic understanding of global paleo-hydroclimatic drivers across a range of boundary
conditions. Here, geophysical analysis of lacustrine sediment stratigraphy at Lago de
Tota, Boyaca, Colombia provided evidence for significant lake-level fluctuations through
the late Quaternary and produced a record that potentially spans the last 60 ka. Seismic
data revealed a series of off-lap and on-lap sequences in the upper ~20 m of sediments
that indicated large amplitude changes in lake-level, driven by variability in the mean
latitude of the Intertropical Convergence Zone as controlled by insolation- and ocean
circulation-driven hemispheric temperature gradients during glacial/stadial and
interglacial/interstadial events. In North America, late Holocene flood recurrence in the
Midwest and Holocene changes in the mean latitude of the polar front jet stream were
investigated through multi-proxy examinations of sediment cores collected from swale
lakes in northern Kentucky and southern Indiana, and a glacially formed kettle lake in
northern Indiana. These results showed that the midlatitude jet stream was displaced to
the south during the late Holocene, which increased the amount of Midwestern
precipitation sourced from the northern Pacific and Arctic, especially during prolonged
cool conditions. During these cool periods, when atmospheric flow was meridional and a
greater amount of precipitation was delivered from the northerly sources, Ohio River flooding increased. During warm conditions, when clockwise mean-state atmospheric
circulation advected southerly moisture from the Gulf of Mexico into the Midwest,
flooding on the Ohio River decreased. At present, streamflow in the Midwest is
demonstrated here to be generally increasing, despite atmospheric conditions typically
associated with reduced streamflow in the paleo-record, due in part to increasing
precipitation and modern land-use dynamics. Together, these studies demonstrate the
sensitivity and vulnerability of local-scale hydrological processes to synoptic climate
change.
| Identifer | oai:union.ndltd.org:IUPUI/oai:scholarworks.iupui.edu:1805/30369 |
| Date | 09 1900 |
| Creators | Gibson, Derek Keith |
| Contributors | Bird, Broxton, Gilhooly, William, III, Jacinthe, Pierre-André, Licht, Kathy, Wang, Xianzhong |
| Source Sets | Indiana University-Purdue University Indianapolis |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
Page generated in 0.0023 seconds