V \f COMBINED ICE ANt> t^ATER BALANCES OF GULKANA AND WOLVERINE GLACIERS, ALASKA AND SOUTH CASCADE GLACIER, WASHINGTON, 1965 AND 1966 HYDROLOGIC YEARS GEQlLOGICAL SURVEY PROFESSIONAL PAPER 715-A \ ' ' ' ) ' I ' ' ' I ' f /// / U \ ': ! / /" ^ ' . \ X'. .- ^». s ""& ^ */* ** >^t. 'S*"V «£ *' r > *; ,#*## 3&.s*e* *' ^ r*- -. jL,4 iJL>~ .>o ^i kV-f " Combined Ice and Water Balances of Gulkana and Wolverine Glaciers, Alaska, and South Cascade Glacier, Washington, 1965 and 1966 Hydrologic Years By MARK F. MEIER, WENDELL V. TANGBORN, LAWRENCE R. MAYO, and AUSTIN POST ICE AND WATER BALANCES AT SELECTED GLACIERS IN THE UNITED STATES GEOLOGICAL SURVEY P R O F E S S I O N A L P A P E R 715-A A contribution to the International Hydrological Decade UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON: 1971 UNITED STATES DEPARTMENT OF THE INTERIOR ROGERS G. B. MORTON, Secretary GEOLOGICAL SURVEY W. A. Radlinski, Acting Director Library of Congress catalog-card No. 70-611617 For sale by the Superintendent of Documents, U.S. Government Printing Office Washington, D.C. 20402 Stock Number 2401-1177 CONTENTS Page Page Abstract._________________________________ _._. Al Descriptions of individual glaciers Continued Introduction. _ _______________________ 1 South Cascade Glacier_ _______ _ _______ A10 Regional physical and climatic setting _________ _ _ _ _ _ 2 Maclure Glacier_____. ___.._._ __________ 11 Measurements.____________ _______________ 11 Geology_________________________ _ .. ___._._._ 2 Ice-balance terms_ _____________________ 11 Climate.______________________________________ 3 Evaluation of errors_ ___________________ 13 Ice balance and altitude. ____________ __________ 3 1965 hydrologic year______ __________________ 13 Glaciers of the Pacific Mountain System. _________ 4 South Cascade Glacier____ ______________ 13 Glaciers of the Rocky Mountain or Eastern System, 7 1966 hydrologic year____ ___________________ 16 Glaciers of the Interior System.__________________ 7 South Cascade Glacier__________________ 16 Descriptions of individual glaciers.___________________ 9 Gulkana Glacier_ ______________________ 19 Gulkana Glacier ______________________________ 9 Wolverine Glacier______________________ 21 Wolverine Glacier,___________________________ _ 10 References _____________ _____________ 22 ILLUSTRATIONS [ Plates are in pocket] PLATE 1. Map of northwestern North America showing location of study glaciers and distribution of precipitation and glacier equi­ librium lines. 2. Maps and photographs showing physical setting of Gulkana, Wolverine, South Cascade, and Maclure Glaciers, western continental United States. 3. Maps and graphs showing data for 1,965 hydrologic year, South Cascade Glacier, North Cascade Range, Washington. 4. Maps and graphs showing data for 1966 hydrologic year, South Cascade Glacier, North Cascade Range, Washington. 5. Maps and graphs showing data for 1966 hydrologic year, Gulkana Glacier, Alaska Range, central Alaska. 6. Maps and graphs showing data for 1966 hydrologic year, Wolverine Glacier, Kenai Mountains, Alaska. Page FIGURE 1. Graphs showing ice balance versus altitude for representative glaciers_____ _ . A4 2. Photograph of Chenega Glacier, Kenai Mountains, Alaska. __ _ __._________________ ______ 5 3. Photograph of eastern Alaska Range in interior Alaska_ _____ ___________ _____ __________ 6 4. Photograph of Ladder Creek and Neve Glaciers in North Cascades National Park, Washington 8 5. Photograph of the Sierra Nevada, California-___ _ _ ___ ______ ____________________-_--_ 9 6. Diagram illustrating the combined system for ice-balance terms._______________ ____________ 12 7. Photograph of South Cascade Glacier and basin in September 1966 _ .._ ._._____. 18 TABLES Page TABLE 1. Instrumentation at South Cascade Glacier during the 1965 hydrologic year_______ _ ______ A13 2. Snow, ice, and water balances, South Cascade Glacier, 1965 hydrologic and balance years_ 14 3. Instrumentation at South Cascade Glacier during the 1966 hydrologic year_ __________ 16 4. Snow, ice, and water balances, South Cascade Glacier, 1966 hydrologic and balance years_ 17 5. Instrumentation at Gulkana Glacier during the 1966 hydrologic year_ __________________ 19 6. Snow and ice balances, Gulkana Glacier, 1966 hydrologic year ___________________ 20 7. Instrumentation at Wolverine Glacier during the 1966 hydrologic year__________________ 21 8. Snow and ice balances, Wolverine Glacier, 1966 hydrologic year______________--_------ 22 in ICE AND WATER BALANCES AT SELECTED GLACIERS IN THE UNITED STATES COMBINED ICE AND WATER BALANCES OF GULKANA AND WOLVERINE GLACIERS, ALASKA, AND SOUTH CASCADE GLACIER, WASHINGTON, 1965 AND 1966 HYDROLOGIC YEARS By MARK P. MEIER, WENDELL V. TANGBORN, LAWRENCE R. MAYO, and AUSTIN POST ABSTRACT The annual balance of South Cascade Glacier at the end of the Glaciers occur in northwestern North America between lat 37° 1965 hydrologic year was slightly positive (+0.07 m averaged over and 69° N. in two major mountain systems. The Pacific Mountain the glacier), but continued ablation and deficient accumulation in System, near the west coast, receives large amounts of precipita­ October 1965 resulted in slightly negative net balances for both the tion, has very mild temperatures, and contains perhaps 90 percent glacier and the drainage basin. Factors tending to produce this of the glacier ice. The Rocky Mountain or Eastern System, on the near-zero balance were the above-average late-winter balance other hand, receives nearly an order of magnitude less precipita­ (3.48 m) and the numerous summer snowfalls. Ice ablation aver­ tion, has temperatures that range from subpolar to subtropic, and aged about 39 mm of water per day during the main melt season. contains glaciers that are much smaller in both size and total area. Runoff during the summer ablation season was lower than the As a contribution to the International Hydrological Decade pro­ 1958-64 average. gram on combined balances at selected glaciers, the U.S. Geological The South Cascade Glacier annual balance in 1966 ( 0.94 m) Survey is conducting studies of ice and water balance on four gla­ was considerably more negative mainly owing to the deficient win­ ciers in the Pacific Mountain System: Wolverine and Gulkana ter snowpack (the late-winter balance was only 2.52 m) and the Glaciers in Alaska, South Cascade Glacier in Washington, and warm dry summer. Ice ablation averaged about 44 mm of water Maclure Glacier in California. Similar data are being collected by per day during the melt season. The loss in storage of this other organizations at five glaciers in western Canada, including and other glaciers in the North Cascades increased the runoff of two in the Rocky Mountain System, and at one glacier in the many valley streams by approximately 50 percent during August Rocky Mountain System in northern Alaska. and September. Gulkana, Wolverine, South Cascade, and Maclure Glaciers have The 1966 Gulkana Glacier annual balance was slightly positive dissimilar mass balances, and each is fairly representative of the ( + 0.06 m); on the basis of past observations and the rapid ter­ glaciers for its particular region. Gulkana Glacier (lat 63°15' N., minus retreat of this glacier, this value is considered unusual. Alaska Range, Alaska) normally has an equilibrium line at an alti­ Accumulation (late-winter balance) was probably near the average tude of 1,800 m (meters), an activity index of about 6 mm/m of recent years. The ablation season was quite short, ending over (millimeters per meter), a winter balance of about 1.0 m, and an most of the glacier on August 15; this factor alone probably annual exchange of about 2.2 m. (Balance values are given in terms accounts for the slightly positive balance. Ice ablation averaged of water-equivalent measure; the winter balance of 1 m, for ex­ approximately 26 mm of water per day during the melt season. ample, indicates a volume of ice equal in mass to a volume of water Runoff from this glacier was not measured in 1966 but is estimated 1 m in depth covering the area of the glacier.) The normal approxi­ on the basis of ice-balance and precipitation data to be about 2 m, mate parameters for the other glaciers studied are as follows: which is 5-10 times the amount measured in nearby lower altitude Wolverine Glacier (lat 60°24' N., Kenai Mountains, Alaska) basins. equilibrium-line altitude 1,200 m, activity index 9 mm/m, winter In the Kenai Mountains of Alaska, the 1966 Wolverine Glacier balance 2.5 m, and annual exchange 5.5 m; South Cascade Glacier annual balance was negative ( 0.26 m); the winter balance (lat 48°22' N., North Cascades, Wash.) equilibrium-line altitude (1.83 m) was based on precipitation records at nearby Seward and 1,900 m, activity index 17 mm/m, winter balance 3.1 m, and was probably deficient. Ice ablation was heavy during the summer annual exchange 6.6 m; and Maclure Glacier (lat 37°45' N., Sierra (about 50 mm of water per day average). Nevada, Calif.) equilibrium-line altitude 3,600 m, activity index Collection of data on ice and water balance for Maclure Glacier 23 mm/m, winter balance 2.3 m, and annual exchange 4.6 m. began in late 1966 and will be given in subsequent reports. Mass balances of these four glaciers and their drainage basins are measured annually by standard glaciological techniques. In INTRODUCTION addition, the hydrologic balance is calculated using streamflow and The International Hydrological Decade (IHD), 1965- precipitation measurements. Combining these independent meas­ 74, was launched