Morphodynamic and Slope Instability Observations at Wabush Lake, Labrador D. Turmel, J. Locat, G. Cauchon-Voyer, C. Lavoie, P. Simpkin, G. Parker, and P. Lauzière Abstract Since 1964, Iron Ore Company of Canada (IOCC) has deposited iron tailings resulting from mining operations into Wabush Lake, Western Labrador. Bathymetric surveys were carried out between 2004 and 2008 as part of the overall environmental IOCC plans to maintain safe disposal strategies of tailings into the lake. In this paper, we present the evolution in distribution and morphological char- acteristics over the last 4 years of the tailings overlying lacustrine sediments and bedrock. In 2004, a high definition multibeam survey of Wabush Lake was carried out for the first time and revealed lake floor features, including a fine network of channels and a delta foreslope with well-developed knickpoints. Other features such as older subaqueous mass movement scars and an esker were also identified. The delta foreslope channels, in 2004, led into a deeper long channel connected with the deepest part of the lake where turbidite deposition took place. A second bathymet- ric survey was carried out in 2006. Many of the features seen on the 2004 map were already buried by the advancing delta front. Results indicate that the 2004 channel system was almost completely obliterated with the generation of many new others. Development of the knickpoints is also observed where some are still present and D. Turmel (), J. Locat, and G. Cauchon-Voyer Laboratoire d’études sur les risques naturels, Département de géologie et de génie géologique, Université Laval, Québec, G1K 7P4, Canada e-mail: dominique.turmel.1@ulaval.ca C. Lavoie Department of Geosciences, Hamilton College, Clinton, New York, 13323, USA P. Simpkin IKB Technologies Limited, 1220 Hammonds Plains Road, Bedford, Nova Scotia, Canada B4B 1B4 G. Parker Ven Te Chow Hydrosystems Lab, Department of Civil Engineering, College of Engineering, University of Illinois at Urbana-Champaign, IC 61802, USA P. Lauzière Iron Ore Company of Canada, Environment Department, P.O. Box 10000, Labrador City, NL, Canada A2V 2L8 D.C. Mosher et al. (eds.), Submarine Mass Movements and Their Consequences, 435 Advances in Natural and Technological Hazards Research, Vol 28, © Springer Science + Business Media B.V. 2010