Determining winter discharge based on hydraulic modeling

Abstract

At present, the only accurate means of determining discharge under ice-affected conditions is by direct measurement, a costly undertaking that places field staff at personal risk. Consequently, winter discharge hydrographs are often based on interpolation between relatively infrequent direct measurements. This study explores the viability of using gradually varied flow hydraulic modeling to determine winter discharge. Based on an analysis of data obtained on the Mackenzie River near Fort Providence, Northwest Territories, and on the Athabasca River at Fort McMurray, Alberta, it appears that the errors associated with this approach could be as low as 3%. The potential applicability of stage–fall models based on hydraulic model data is also explored as a means to facilitate automated winter discharge measurements. Indications are that the viability of stage–fall modeling is highly dependent on identifying a suitable reach and establishing an adequate range of data. Hydraulic modeling has the potential to address both these issues.Key words: streamflow measurement, rivers, ice, hydraulic modeling, stage–fall analysis.