Tuesday, 28 August 2007 - 10:50 AM
2.A.D-3

Trends in Discharge and Flow Season Timing of the Onyx River, Wright Valley, Antarctica Since 1969

Michael N. Gooseff, Civil & Environmental Engineering Department, Pennsylvania State University, 212 Sackett Hall, University Park, PA 16802, Diane M. McKnight, Institute of Arctic and Alpine Research, University of Colorado, 1560 30th St., Boulder, CO 80301, Peter Doran, Department of Earth and Environmental Sciences, University of Illinois at Chicago, 845 W. Taylor St., Chicago, IL 60607, and W. Berry Lyons, Byrd Polar Research Institute, The Ohio State University, 1090 Carmack Rd, Scott Hall, Columbus, OH 43210.

Flow records at the two stream gauges on the Onyx River represent the longest actively collected environmental records in the McMurdo Dry Valleys, Antarctica.  The downstream gauge, near Lake Vanda, has been collecting data since 1969, and the upstream gauge, at Lower Wright Glacier (LWRT), has collected data since 1972.  We analyzed these records to assess the long-term trends in annual discharge, flow season length, flow season start, and flow season end.  Our results indicate overall decreasing trends in annual discharge (0.4x106 m3/decade at LWRT, 0.8 x106 m3/decade at Vanda), and increasing flow season lengths (by 7 d/decade at LWRT, and 2.7 d/decade at Vanda), influenced by earlier start and later end dates (5.2 and 0.8 d/decade, respectively at LWRT; 4.8, 1.4 d/decade, respectively at Vanda).  This suggests that flow season climate patterns in the Dry Valleys are decreasing glacier melt intensity overall, but extending the period of meltwater generation.

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