Spatial and temporal patterns of break‐up and ice‐jam flooding in the Mackenzie Delta, NWT

• Published in: Hydrological Processes
• Main Authors: Goulding, Holly L., Prowse, Terry D., Beltaos, Spyros
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2009
• Subjects: Arctic; Mackenzie River; Mackenzie Delta; Marr; Arctic Red River; Delta Peak; Mackenzie river
• Online Access: http://dx.doi.org/10.1002/hyp.7251; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fhyp.7251; https://onlinelibrary.wiley.com/doi/pdf/10.1002/hyp.7251

Abstract The Mackenzie Delta is covered in freshwater lakes that provide habitat for a myriad of species. The hydrology and ecology of these delta lakes are dominated by cryospheric processes, specifically spring break‐up ice jams, which typically produce the largest hydrologic event of the year. Despite the importance of ice‐induced flooding in the delta, the patterns and processes characterizing these events are poorly understood. In this paper, archived records at a dozen hydrometric stations in the delta for the period from 1974 to 2006, improved with information from remotely sensed imagery, are used to assemble a break‐up chronology for the delta, and examine the spatial and temporal patterns of break‐up flooding. Analysis of backwater level and discharge at the Mackenzie River at Arctic Red River (MARR) station are used to explain the physical rationale of the resulting patterns. Results highlight years of extensive delta flooding, and within the subset of significant flood years, two event types are identified: (1) ice‐driven events, with high backwater levels at MARR associated with high levels in the southern and eastern/western delta, and (2) discharge‐driven events, with extensive high‐water levels in the mid/outer delta and along Middle Channel, despite lower upstream peak water levels. Temporally, the break‐up initiation during ice‐ (discharge‐) driven events occurs earlier (later) than the delta average. These occur later (earlier) in the time‐series that is trending toward earlier break‐ups. The MARR station is determined to be a suitable index of delta peak water levels for continued investigation into the hydroclimatic controls on extreme hydrological events in the Mackenzie Delta. Copyright © 2009 John Wiley & Sons, Ltd.