Hydraulic modelling of subglacial tunnel channels, southeast Alberta, Canada

One of the key issues associated with the hypothesis of catastrophicsubglacial drainage of the Livingstone Lake event is whether flows of such large magnitudes are physically feasible. To explore this issue, a one-dimensional hydraulic network flow model was developed to investigate the range of peak discharges and associated flow parametersthat may have been carried by a tunnel channel network in south-eastAlberta, Canada. This tunnel channel network has been interpreted elsewhere to carry large discharges associated with subglacial meltwater flows because of the convex longitudinal profiles of individual channels. This computational modelling effort draws upon established andverified engineering principles and methods in its application to the hydraulics of this problem. Consequently, it represents a unique and independent approach to investigating the subglacial meltwater hypothesis. Based on the modelling results, it was determined that energylosses resulting from friction limit the maximum peak discharge thatcan be transported through the tunnel channel network to 10⁷ m³ s^-1, which is in reasonable agreement with previous estimates of flood discharges for proposed megafloods. Results show that flow through channels with convex longitudinal profiles occurs when hydraulic head exceeds 910 m (Lost River) and 950 m (Sage Creek), respectively. These are considerably below the maximum head capable of driving flow through the system of 1360 m, beyond whichice is decoupled from the bed across the pre-glacial drainage divide. Therefore, it is concluded that these model results support the hypothesis of catastrophic subglacial drainage during the Livingstone Lake event. [ABSTRACT FROM AUTHOR]