HR: 1340h
AN: GC33A-1244    [Abstracts]
TI: The Record of Extreme Hydrologic Events in Annually-laminated (Varved) Lake Sediments, Southern Coast Mountains, British Columbia, Canada
AU: * Menounos, B
EM: menounos@unbc.ca
AF: Geography University of Northern British Columbia, 3333 University Way, Prince George, BC V2N 4Z9 Canada
AU: Gilbert, R
GC33A-1244 AF: Department pf Geography Queen's University, Mackintosh Corry Hall, Kingston, ON K7L 3N6 Canada
AU: Clague, J
GC33A-1244 AF: Department of Earth Sciences Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6 Canada
AU: Crookshanks, S
GC33A-1244 AF: Department pf Geography Queen's University, Mackintosh Corry Hall, Kingston, ON K7L 3N6 Canada
AU: Hodder, K
GC33A-1244 AF: Department pf Geography Queen's University, Mackintosh Corry Hall, Kingston, ON K7L 3N6 Canada
AB: Long hydro-climatic records are required to detect changes in the magnitude and frequency of extreme events, but are often absent in mountain environments. Varve chronologies from five proglacial lake basins detail changes in the regional hydro-climate of southern British Columbia over the past 400 years. This region is ideally suited to assess the relation between hydro-meteorology and sediment transport given the quality and length of parallel instrumental records. Lake sedimentation documents snowmelt and glacier runoff, and floods. Despite significant differences in lake basin size and contributing watershed character, substantial correspondence is observed among the records. Thickest varves are produced in years with significant floods. However, the strength of the relation between flood magnitude and lake sedimentation varies within a given lake and between lake basins. Flood deposits consisting of graded laminae and beds can be identified and measured in thick (> 5 mm) varves and clarify the relation between hydrologic forcing and sediment response. A pronounced change in the nature of lake sedimentation, accompanied by higher inter-annual variability, occurred in 1980. The change coincides with an increase in the frequency and magnitude of autumn flooding and is coincident with a re-organization of the North Pacific climate system. These results highlight new directions for paleo-environmental research using varve records to study the magnitude and spatial extent of past hydro-climatic events and to distinguish them from other catastrophic events such as landslides and glacier surges unrelated to hydro-climatic forcing.
DE: 0720 Glaciers
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1821 Floods
DE: 3344 Paleoclimatology (0473, 4900)
SC: Global Climate Change [GC]
MN: Fall Meeting 2005