Toward the Use of Modern Hydrologic Modeling Tools in Paleoclimate Studies

For decades, paleoclimatological proxy data such as tree rings, stable isotope data, and shore line dating of pluvial lakes, have been used to reconstruct past climate by means of simple water and energy balances. The lack of spatial and temporal resolution in these often lumped basin-average approaches might preclude the user from taking full advantage of the proxy information, which by nature offer only snapshot views of past conditions. Modern hydrologic modeling tools provide a means to investigate hydrologic system response to past climate conditions in high spatial and temporal resolution.;This work presents the application of a spatially distributed monthly water balance model, the U.S. Geological Survey's Thornthwaite model, to explore the link between past climates, paleoclimate proxies, and hydrologic system response in two closed basin-lake systems in the Great Basin. A model calibration strategy is tested on a present-day application to explore modern proxy data that can be useful in calibrating and driving hydrologic models in ungauged watersheds. In two paleo applications, the model is used with proxy data such as shoreline dating and relict tree stumps to investigate how climate and hydrologic conditions in the two systems differed from today's conditions; to evaluate the differences in watershed response to past climate conditions when explored with the traditional lumped water balance approach vs. the spatially and temporally distributed combined water and energy balance model; and to explore specific research questions that would be difficult to answer with a lumped approach.