ABSTRACT: Contemporary (1951-2001) evolution of lakes in the Old Crow Basin, Northern Yukon, Canada: Remote sensing, numerical modeling, and stable isotope analysis.

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Abstract

This study reports on changes in the distribution, surface area and modern water balance of lakes and ponds located in the Old Crow Basin, northern Yukon, over a 50-year period (1951-2001) using aerial photographs, satellite imagery, a numerical lake model, and stable O-H isotope analysis. Results from the analysis of historical air photos (1951 and 1972) and a Landsat-7 Enhanced Thematic Mapper (ETM+) image (2001) show an overall decrease (-3.5%) in lake surface area between 1951 and 2001. Large lakes typically decreased in extent whereas ponds generally increased over the study period. This is corroborated by a numerical lake water balance simulation (P-E index) and stable O-H isotope analysis, which indicates that most lakes experienced a water deficit over the period 1988-2001. These observed trends in lake surface area are mainly attributable to a warmer and drier climate. The modern decrease in lake levels corresponds well to changes in regional atmospheric teleconnection patterns (Arctic and Pacific Decadal oscillations). In 1977, the climate in the region switched from a predominantly cool and moist regime, associated with the increase in lake surface area, to a hot and dry one, thus resulting in the observed decrease in lake surface area. Although some lakes may have drained catastrophically by stream erosion or bank overflow, it is not possible to determine with certainty which lakes experienced such catastrophic drainage since the air photos and the satellite image were acquired at about a 20-year interval.

Bibliography of Canadian Geomorphology