A six-year isotopic record of lake evaporation at a mine site in the Canadian subarctic: results and validation

• Main Authors: J J Gibson, R Reid, C Spence
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1998
• Subjects: Canada; Northwest Territories; Yellowknife; Subarctic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1054.6826; http://www.science.uwaterloo.ca/%7Ejjgibson/mypdfs/sixyr.pdf

Abstract: An isotopic method is applied in conjunction with a water balance method and the Penman combination method to estimate evaporation from a small, high closure (low out¯ow) lake near Yellowknife, Northwest Territories, Canada (62803 The study provides baseline hydrological information for assessment of tailings pond design and management at nearby mine sites, and, notably, enables intercomparison of several ®eld-based evaporation methods and a standard climate approach in a subarctic setting. A non-steady isotope mass balance method is applied to estimate evaporation over time intervals ranging from ®ve days to three weeks, based on isotopic surveys of lake water, groundwater, precipitation and atmospheric moisture during the open water periods of 1991 to 1996. Use of a relatively high precision non-steady technique, in contrast to the commonly employed approach assuming steady state, is feasible in the present setting owing to pronounced seasonal evaporative enrichment in lake water (20±30 times analytical uncertainty of d 18 O). A comparative analysis reveals that the isotopic method is conservative relative to the Penman combination method, but less conservative than standard water balance, although estimates for the open water period are in agreement to within 20% in both cases. Interannual variability in evaporation is revealed to be 30±50% greater than predicted from standard pan-to-lake algorithms, and of the same order of magnitude as the annual snow water equivalent (5±175 mm), which has important implications for the design and management of tailings ponds in the area. #