The Annual Emptying of Lake George, Alaska

Résumé

Description and partial interpretation of the natural emptying of this ice-dammed lake in south-central Alaska. Regional and site characteristics, the 1951 observations and other emptyings since 1935 are described; and the age of the lake as evidenced by terracettes, willows, alders, and exposed deltas, is considered. When studied July 20, 1951, it was about 2-4 mi wide, 11-12 mi long, 114 ft deep, and dammed by Knik Glacier. In 12 days, the lake water had undercut the glacier ice and escaped, leaving three small, shallow lakes with 42 % less water surface. The drop in level (up to 12 in/hr) was accompanied by the rise of Knik River from 7 to nearly 20 ft depth, and flooding. A trend is noted toward earlier emptying and greater flooding.