Research Reports
Post-incident Impact Assessment of the Saguenay Flood Disaster on the Marine and Coastal Environment and Communities

Jacques Locat
Laboratoire d'études sur les risques naturels (LERN)
Groupe de recherche en géo-ingénierie et en environnement (GREGI)
Département de géologie et de génie géologique, Université Laval, Québec

Download full text of the report in PDF

Executive Summary
In July 1996, an exceptional climatic event left more than 200 mm of rain in the Saguenay-Lac-Saint-Jean region and had devastating effects on the people of that region as well as on the terrestrial infrastructures. Another devastating effect was the accumulation of more than 20 million tonnes of sediments in the upstream portion of the Saguenay Fjord, of which a good part came from the avulsion of the Ha! Ha! River and the intensive erosion of other major tributaries of the Saguenay Fjord region. Not long after the flood, a research team was assembled to evaluate the potentially positive impact of that disaster; the new layer of sediments had covered contaminated sediments that lie at the bottom of the fjord. This team initiated the study, Efficiency of the catastrophic capping layer of July 1996 in acting as a barrier against contaminated sediments: an opportunity for technological advancement.

The scientific results obtained from numerous research projects have been published as articles in many research journals or disclosed during conferences. The synopses of the symposium on the Saguenay flood, a symposium held at the onset of the project and in which OCIPEP¹ participated, are available at www.ocipep.gc.ca/research/resactivites/natHaz/
saguenay/1998_D001_e.asp. The last scheduled activity related to the Saguenay post-flood has taken place during the 2nd International Symposium on Contaminated Sediments that was held in Québec City in May 2003. This report outlines the results obtained from the special session on the Saguenay post-flood and emphasizes the various contributions and conclusions drawn from the research projects. These results will also be analyzed in light of OCIPEP's concerns.

Conclusions drawn from the various research projects include:

1. That it is possible to rapidly deploy research teams in order to estimate the effect of natural disasters on the marine environment and shoreline communities. This is due to the development and pooling of tools in the domains of chemistry, biology, geotechnics, and geophysics.
2. The layer resulting from the 1996 flood, although unevenly distributed, acted as an efficient protection layer against the migration of contaminants found in underlying sediments.
3. The repercussion of the flood on the benthic fauna has been beneficial in providing a protection layer limiting the access of these organisms to the contaminants. In the long term, this should help reduce the level of contaminants in the food chain of the animals that feed on the benthic fauna.
4. The coastal damage is limited to the areas close to river deltas.

The local and regional infrastructures associated with the use and exploitation of the fjord's aquatic environment after the 1996 flood are finding conditions even more favourable in terms of water quality as well as benthic fauna.

This material is based upon work supported by the Division of Research and Development (DRD) in the Office of Critical Infrastructure Protection and Emergency Preparedness (OCIPEP), under Contract Reference No. 2003D011. On 12 December 2003, the Office of Critical Infrastructure Protection and Emergency Preparedness was integrated into a new department, Public Safety and Emergency Preparedness Canada (PSEPC). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of Public Safety and Emergency Preparedness Canada.

HER MAJESTY THE QUEEN IN RIGHT OF CANADA (2004)
Catalogue No.: PS48-4/2004E-PDF
ISBN: 0-662-36748-0

On 12 December 2003, the Office of Critical Infrastructure Protection and Emergency Preparedness (OCIPEP) was integrated into a new department, Public Safety and Emergency Preparedness Canada (PSEPC).