Evaluation of extreme events (ice jams) and deep scour holes on Mackenzie Delta Channels

Regions: Inuvialuit Settlement Region, Gwich'in Settlement Area

Tags: physical sciences, hydrology, spring breakup, ice jams, hydrography, delta floodplain, river current

Principal Investigator: Prowse, Terry D (12)
Licence Number: 13944
Organization: Water and Climate Impacts Research Centre, Universiy of Victoria
Licenced Year(s): 2008 2007 2006 2005 2004
Issued: Feb 20, 2006
Project Team: Dr. Daniel L. Peters (Research Scientist, NWRI/W-CIRC/UVic), Dr. Spyros Beltaos (Research Scientist, NWRI/CCIW), Dr. B.G. Krishnappan (Research Scientist, NWRI/CCIW), Mr. Tom Carter (Research Technician, NWRI/NHRC), Mr. Martin Lacroix (Physical Scientist, NWRI/W-CIRC/UVic)

Project Description: This is Year 3 of a research project that examines extreme flooding and deep scour holes along the Mackenzie River. Ice jamming has a great influence on channel construction and destruction, formation of deep scour holes in the bed of channels, and flooding of the adjacent delta landscape. Hence, ice jams are of practical concern in the development of infrastructure, ecology of the delta and day-to-day activities of northerners. The objectives of the study are to 1) quantify the frequency and magnitude of ice jams at Mackenzie River at Arctic Red and downstream on the delta channels, 2) determine the hydroclimatic conditions controlling the occurrence of ice jams and associated floods, as well as the source areas generating the spring hydrograph on the lower Mackenzie River; 3) develop/calibrate a hydraulic model of ice jamming for the Mackenzie Delta, and 4) investigate the importance of deep scour holes, which can be up to 30 m deep or five to six times the average channel depth. This water resources-related project will assist in guiding future climate change impacts and adaptation research for the Mackenzie Delta region.

Quarterly field trips are tentatively scheduled for mid-March, late May or early June, late July or early August, and late September, depending on river conditions. Skidoos/toboggans towing the Ground Penetrating Radar (GPR) gear will be used to qualify the underlying stratigraphy of the scour holes in March at select sites. The channel ice will be cored using power augers, and the core will be used to calibrate the GPR and conduct geochemical/stable isotope analyses. GPR will also be used to quantify ice thickness along the channels and investigate any anomalous ice formations. Shallow (1-2 m) sediment cores will be extracted from the channel bed at the scour hole sites, which will be used to ground-truth the radar returns. Detailed channel cross-section surveys (GPR, Sonar, total station, etc) will be conducted at key ice jamming sites and historical flood levels will be geo-referenced. The sites will be revisited during the open-water period to perform additional surveys.

The study will be conducted from March 1 to October 31, 2006 at Middle Channel near Horseshoe Bend (68° 18' 134° 25'), East Channel (Scour Hole #10, 68° 14' 3" 133° 49' 9"), and Mackenzie River at Tsiigehtchic (67° 27' 23" 133° 45' 13").