Ice effects on flow distributions within the Athabasca Delta, Canada

• Published in: River Research and Applications
• Main Authors: Andrishak, R., Hicks, F.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2011
• Subjects: Athabasca River; Canada; Peace-Athabasca Delta; Lake Athabasca
• Online Access: http://dx.doi.org/10.1002/rra.1414; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Frra.1414; https://onlinelibrary.wiley.com/doi/pdf/10.1002/rra.1414

Abstract The Peace‐Athabasca Delta (PAD) is a unique and ecologically sensitive area made up of many interconnected lakes, wetlands, streams and rivers. The hydrology of the Delta is heavily influenced by inflows from the Athabasca River and the complex river ice regime within it. In this study, a detailed one‐dimensional network hydraulic model of the Athabasca River Delta (comprising the southern portion of the PAD) is presented and applied to demonstrate how variable stream‐flow and ice cover conditions affect the distribution of flow among the major channels conveying water to Lake Athabasca and the rest of the Delta. The current channel network model, based on new measurements concentrated at the main channel junctions combined with carefully designed geometry throughout the un‐surveyed reaches, is shown to provide flow allocations to the major channels that are within 3% of the corresponding observations. At the three main flow‐split junctions, steady flow simulations at varying discharge, Lake Athabasca level, and ice thickness were performed to assess their impact on the percentage of flow carried by each channel. Each junction was found to exhibit a unique response arising from its physical geometry and location within the Delta. Transient simulations for the historical period 1960–2007 demonstrate that water demand on the Athabasca River upstream of the PAD may have a significant impact on the availability of fish habitat in winter. Imposing a 20 m 3 /s water demand increased the total occurrences of a no‐flow condition in the Fletcher Channel, analogous to it freezing to the bed, by 53%. Copyright © 2010 John Wiley & Sons, Ltd.