Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Geography & Environmental Studies

Faculty/School

Faculty of Arts

First Advisor

Michael English

Advisor Role

Thesis Supervisor

Abstract

The purpose of this thesis is to investigate the hydrological dynamics of Gornerglestcher and Findelengletscher, Switzerland by performing hydrochemical analyses on the bulk runoff exiting the portal of these two alpine glaciers. The hydrochemical analyses utilized electrical conductivity, as a surrogate for total dissolved solids, to determine the flow of routing of the bulk runoff (englacial or subglacial as defined by Collins, 1979b) and 8^18O to determine the contributions of pre-event and event water to bulk runoff during precipitation events. The pre-event water was defined as a combination of snow meltwater, ice meltwater and groundwater as these flow components could not be separated individually by using only oxygen-18. Relative contributions to total runoff using these two separation methods was quantitatively determined using a two-component mixing model. Sampling was carried out during the 1990 melt season and although Findelengletscher was to be the focus of this research, problems with field equipment resulted in the concentration of the work on Gornergletscher. The objective of this study was achieved by: a) analyzing a series of hydrologic cycles over periods of 24 hours during non-precipitation events (dry weather) for a portion of the melt season to examine the progressive development of the glacial hydrologic system and by; b) analyzing a series of hydrologic cycles over periods of 24 hours during various precipitation events for a portion of the melt season to examine the reaction of the glacial hydrologic system to a variety of conditions. During these 24 hour sampling periods, hourly mean values for discharge, air temperature, and total radiation as well as hourly total values for precipitation were obtained from local meteorological stations operated by the Grande Dixence Hydroelectric Company. Also, continuous electrical conductivity measurement, discrete hourly samples of suspended sediment concentration and discrete hourly water samples for potential ^18O analyses were obtained from the proglacial stream. Results show that the response of Gornergletscher’s hydrologic system to a precipitation event is a function of the antecedent water saturation level of the glacier. Basically, if the water pressure if high preceding an event the storm peak will consist mostly of pre-event water displaced from the glacier by a “piston-flow” mechanism. In contrast, if the water pressure is low preceding an event, the storm peak consists mostly of event water. In both cases, the volume of water within the storm peak only accounts for a small proportion of the volume of water received as rain. Therefore most of the event water contributes mostly to storage. It was observed that the water displaced from the glacier body during a rain event consisted of englacial water and this displacement did not extend to the subglacial conduit system. A comparison showing the transition of 8^18O concentrations in bulk runoff for Gornergletscher and Findelengletscher for the times of maximum and minimum discharge for one diurnal cycle provides information that makes previously published work regarding the storage capacity of Gornergletscher questionable.

Convocation Year

1992

Convocation Season

Fall

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