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QUANTIFYING THE RELATIVE EFFECTS OF CLIMATE AND CATCHMENT CONTROLS UPON ISOTOPIC MASS BALANCES IN LAKES OF THE NORTH AMERICAN GREAT PLAINS (E)

Aquatic systems in the Northern Great Plains are known for their sensitivity to changes in regional climate; however, the extent to which lake and catchment-specific characteristics modify the influence of climate upon water mass balance is not clearly understood. Lake-specific characteristics (e.g. volume, area), and catchment characteristics (e.g. effective drainage, ground cover) influence water availability by modifying evaporation to input (E/I) ratios, source water isotopes (summer vs winter precipitation vs groundwater), and water yield. To better understand how the water balances of prairie lakes are affected during pluvial periods we used standard isotopic mass balance techniques to assess 105 lakes across a 260 000 km2 area. Lakes fell into three hydrological regimes; open (n = 50, 48%), restricted (n = 39, 37%), or closed (n = 16, 15%) and no consistent relationship with climatic gradients or geographic position. Source waters (as δ 18O) ranged from -7.2‰ indicating (rain only) to -29.3‰ (snowpack). Unexpectedly, median values of input waters (-14.5‰) suggest that summer precipitation sustains these systems despite contributing a wide range of water influx (0-1.9 m depth equivalent). These calculations support E/I-based classifications of lake hydrology, with closed basins receiving only minimal catchment input. Overall, the high variability in lake connectivity indicated by isotopic mass balance suggests that individual lake catchments act as a basin-specific filter upon regional climate.

Authors

Haig, H. A., University of Regina, Canada, haig.a.heather@gmail.com

Hayes, N. M., University of Regina, Canada, nicole.hayes@uregina.ca

Simpson, G. L., University of Regina, Canada, gavin.simpson@uregina.ca

Hodder, K. R., University of Regina, Canada, kyle.hodder@uregina.ca

Leavitt, P. L., University of Regina, Canada, peter.leavitt@uregina.ca

Details

Oral presentation

Session #:075
Date: 03/01/2017
Time: 15:15
Location: 306 B

Presentation is given by student: Yes