Authors: R. Zhou, R. Donnelly
Canadian Dam Association Conference, Winnipeg, September 2008
Abstract
There is currently no general accepted procedure and methodology for assessing the potential for loss of life due to downstream channel erosion and bank failure following a dam break event. Typically losses are estimated by comparing the flood water levels with and without an assumed dam failure. If the incremental flooding does not lead to additional inundation of homes or buildings, it is generally assumed that there is no life safety hazard. However, erosion and bank failure after dam breach can and does occur that can have the potential to lead to incremental life safety hazards and environmental impacts. Houses and buildings located near the river banks, which would normally considered to be safe since they are situated above the maximum elevation of the flood waters, could be at risk due to the
potential for bank failure as a result of scour during the flood event. For example, the dam break event in Saguenay, 1996 presented a real case example of how severe this type of hazard could be.
This paper describes a general procedure and methodology to evaluate the potential for geomorphic incremental hazard that can be used in a dam safety assessment where appropriate. Following this procedure, the potential for geomorphic erosion and bank failure is first evaluated based on a simple bank stability assessment model. If there is very little chance of bank failure in the downstream area, the evaluation stops. If the possibility is high, a dynamic model is used to better simulate the
flood and erosion processes.
