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, climatology, hydrology, prediction models, ice jams, delta floodplain, ecological survey

Principal Investigator: Prowse, Terry D (12)
Licence Number: 14122
Organization: Water and Climate Impacts Research Centre, University of Victoria
Licenced Year(s): 2008 2007 2006 2005 2004
Issued: Mar 01, 2007
Project Team: Dr. Daniel L. Peters (Research Scientist, Environment Canada/W-CIRC/UVic), Dr. Spyros Beltaos (Research Scientist, Environment Canada/CCIW), Dr. B.G. Krishnappan (Research Scientist, Environment Canada/CCIW), Mr. Tom Carter (Research Technician, Environment Canada/NHRC), Mr. Martin Lacroix (Physical Scientist, Environment Canada/W-CIRC/UVic), Ms. Holly Goulding (Graduate Student, Department of Geography, UVic)

Objective(s): The objectives of this study are to quantify the frequency and magnitude of ice jams in the Mackenzie River Delta, including the hydroclimatic conditions controlling their occurrence and associated floods, develop a hydraulic model of it, and investigate the importance of deep scour holes in the Mackenzie River.

Project Description: The objectives of this study are to quantify the frequency and magnitude of ice jams in the Mackenzie River Delta, including the hydroclimatic conditions controlling their occurrence and associated floods, develop a hydraulic model of it, and investigate the importance of deep scour holes in the Mackenzie River.

This study is an expansion of previous research conducted in 2004. Ice jamming has a great influence on channel formation, scour holes, and flooding and is of concern in the development of infrastructure (e.g., pipeline crossings), ecology (e.g., over-wintering of fish, recharging isolated delta lakes), and in activities of northerners. The objectives of this study are: 1) to quantify the frequency and magnitude of ice jams on the Mackenzie at Tsiigehtchic and in the delta, 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, 3) develop 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 6 times the average channel depth).

Quarterly field trips are scheduled for mid-March, May/June, July/August, and late September, depending on river conditions. Skidoos towing the Ground Penetrating Radar (GPR) will be used to determine ice thickness, stratigraphy of the scour holes, and investigate any anomalous ice formations. The channel ice will be cored using power augers. The core will be used to calibrate the GPR and conduct isotope analyses. 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 georeferenced. The sites will be revisited during the open-water period to perform additional surveys.
The ice jam portion of the study will be based at known ice jamming and flooding sites (e.g., Aklavik) and at the hydrometric stations downstream of Arctic Red. The scour hole portion of the study will concentrate on the East Channel of the Mackenzie River.

A presentation of preliminary results and demonstration of Ground Penetrating Radar will be given to interested students and community organizations.

The study will be carried out from March 1 to October 31, 2007. Field locations of interest are: Middle Channel near Horseshoe Bend (68 18'N, 134 25'W), East Channel (Scour Hole #10) (68 14' 3"N, 133 49' 9"W), near Willy Simon’s cabin, and Tsiigehtchic (67 27' 23"N, 133 45' 13"W).