CGRG Bibliography of Canadian Geomorphology
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Author : Clark, I.D.; and Lauriol, B.
Date : 1997
Title : Aufeis of the Firth River basin, northern Yukon, Canada: insights into permafrost hydrology and karst
Publication : Arctic and Alpine Research
Issue : 29(2):
Page(s) : 240-252
Abstract
The 31-km2 aufeis ice sheet of the upper Firth River holds a wealth of information on groundwater hydrology in periglacial environments. Baseflow recession calculations, corrected for aufeis storage (12% of basin discharge), indicate specific groundwater recharge rates of up to 100 mm yr-1 (up to 50% of runoff), suggesting a significant proportion of drainage from karst. The upper Firth River aufeis is a composite aufeis, with discrete baseflow contributions from different watersheds. Since the late Pleistocene, annual growth of the aufeis has exerted a strong control on lateral erosion and the local river channel geomorphology. Two groundwater recharge processes are distinguished on the basis of carbonate geochemistry and o13C: (1) Methanogenic groundwaters, with 13CDic up to -3.3%, are recharged through saturated soils underlain by permafrost; conditions which support anaerobic consumption of dissolved organic carbon (DOC) and produce up to 700 ug-CH4 L-1 (calculated), and (2): Karst groundwaters, with 13C-depleted DIC, recharged through unsaturated soils and circulate through the fissured talik in the carbonate bedrock. Most drainage from the region shows varying contributions of these two groundwaters, although ha greater contribution from the methanogenic groundwaters occurs in north-facing watersheds. The o13C values for cryogenic calcite precipitates in the ice indicate that the karst groundwaters are the major contribution to aufeis growth. The combined use of o18CDIC and geochemistry may be a useful tool to quantify methanogenesis in northern watersheds.
Bibliography of Canadian Geomorphology