Geological Survey Professional Paper 715—A Combined Ice and Water Balances of Gulkana and Wolverine Glaciers, Alaska, and South Cascade Glacier, Washington, 1965 and 1966 Hydrologic Years

The International Hydrological Decade (IHD), 1965-74, was launched to promote international cooperation in research and in the training of specialists and technicians in scientific hydrology. Its purpose is to enable all countries to make a fuller assessment of their water resources and a more rational use of them as demands increase from expanding population, industry, and agriculture. The IHD project concerned with the combined heat, ice, and water balances at selected glacier basins marks an important step in broadening the understanding of snow hydrology, high-mountain and glacier hydrology, and the relation of glacier variations to changes in climate.

Snow is difficult to treat using the usual equations of hydrology because snow accumulation and wastage are complex and not sufficiently understood. Little study has gone into the understanding of snow distribution, the meteorological causes of changes in the snowpack and its physical, thermal, and hydraulic properties, and the hydrology of basins where substantial amounts of water are stored seasonally or from year to year in the form of snow. Drainage basins dominated by glaciers are ideal sites for the study of these problems because there the collection, storage, movement, and release of melt water are dominated by the unique properties of snow and ice. This is an example of thermodynamic hydrology in which the heat balance influences the ice balance and, in the process, largely determines the water balance (UNESCO/IASH, 1970).

The specific objective of this IHD project on heat, ice, and water balances is to obtain sufficient information to define these balances and understand how they change with time at glacier basins in widely differing environments in many parts of the world. To extend the coverage from individual drainage basins to global patterns of atmospheric circulation, chains of glacier-basin stations over the world were recommended for the IHD by the International Commission of Snow and Ice of the International Association of Scientific Hydrology (IASH). One chain of stations extends along the western mountains of the Americas from Arctic Alaska to the Antarctic Peninsula. Another chain extends from the Tien Shan and Pamir Mountains westward through Europe to the west coast of North America, at latitudes between 35° and 55°. A third chain extends from the Polar Urals westward through Scandinavia, Iceland, and Canada to Arctic Alaska, approximately at the Arctic Circle. The McCall, Gulkana, and Wolverine Glaciers in Alaska, the Berendon, Place, and Sentinel Glaciers in the Coast Mountains of British Columbia, the South Cascade Glacier in Washington, and the Maclure Glacier in California form the north-south profile in North America. In addition, McCall and Gulkana Glaciers are the westernmost members of the Arctic Circle east-west chain, and South Cascade Glacier (together with the Place and Sentinel Glaciers) forms the western end of the 35°-55° east-west chain.

This paper first presents a general discussion of the regional and local settings of the glaciers. This is followed by the results for ice and water balances from South Cascade Glacier for the hydrologic years ending on September 30, 1965 and 1966, and results from Gulkana and Wolverine Glaciers for the hydrologic year 1966. Ice and water balances for Maclure, South Cascade, Wolverine, and Gulkana Glaciers will be presented in subsequent years by one publication per hydrologic year. When heat-balance results are compiled, they will be incorporated with the presentations of ice and water balance.

In this report, the introduction, the section on regional setting, and the descriptions of individual glaciers were written by M. F. Meier and Austin Post; precipitation data for Alaska and adjacent Canada were contributed by L. R. Mayo. The results from South Cascade Glacier were supplied by W. V. Tangborn, field leader of that project. The results from Gulkana and Wolverine Glaciers were supplied by L. R. Mayo, field leader of those projects.