Reconnaissance hydrology of Portage Glacier basin, Alaska

Hydrologic Atlas 583
By: , and 



Early reports of conditions in Portage Pass, Alaska, provide evidence that Portage Glacier was formerly larger and thicker. Past conditions, recent history, current retreat, and possible future changes are summarized from an analysis of reports, photographs of the glacier (1939, 1950, and annually since about 1960), and data on snow and ice balance and bathymetry (1972). Between 1900 and 1972, the glacier terminus retreated 3.4 kilometers, and the lower part of the glacier thinned 200 meters. Climatic change controlled the retreat until about 1930; since then deep water at the terminus has influenced the calving retreat. The calving rate and present terminus position cannot be sustained by current climatic conditions and rate of snow accumulation. Thus the glacier will continue to recede until the terminus stabilizes in shallower water, probably about 1.5 kilometers upvalley from the present terminus and in about year 2020, assuming no change in present climatic conditions and calving rate. Possible small climatic changes could cause a shift in the point at which annual snow accumulation equals annual ablation (500 meters) and a corresponding change in terminus behavior. Potential natural hazards include avalanches, outburst floods from ice-dammed lakes, and unstable icebergs. 

Study Area

Publication type Report
Publication Subtype USGS Numbered Series
Title Reconnaissance hydrology of Portage Glacier basin, Alaska
Series title Hydrologic Atlas
Series number 583
DOI 10.3133/ha583
Year Published 1977
Language English
Publisher U.S. Geological Survey
Description 2 Plates: 47.28 × 31.00 inches
Country United States
State Alaska
Other Geospatial Portage Glacier basin
Scale 50000
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