Restoration of hydrogeomorphic processes for fish habitat and the impacts of dam removal on Rivière Saint-Jean, l’Anse-Saint-Jean

Research summary

The July 1996 floods greatly affected rivers in the Saguenay. The intense hydrological response to these events altered the morphology and sediment dynamics of regional rivers. Given these new conditions, communities installed massive bank riprap along several sections of river.

Hydrogeomorphic processes (HGM) are ecosystem services provided by watercourses, serving both habitat and civil protection needs. Riprap use is often justified and fueled by a negative perception of bank erosion. This view can lead to riprap being installed in river stretches where erosion is not important. Such riprap contributes to problems associated with disconnected river margins, leading to altered river systems and a reduced transport of sediments necessary for maintaining hydrogeomorphological processes.

This project focuses on Rivière Saint-Jean, l’Anse-Saint-Jean, Québec, where 71% of the banks have been riprap-coated since 1996. Moreover, the Hydro-Morin dam was erected across the river in 1957, and the watercourse has been modified. All these impacts have led to a sediment deficit in the sector downstream of the dam. These changes in hydrosedimentary dynamics and the modified HGM have negatively affected habitat quality for salmon and sea trout by reducing the surface area and number of potential spawning areas in the river. This project will quantify the hydrosedimentary dynamics of Rivière Saint-Jean as a first step in restoring the river’s natural hydrogeomorphological processes.

Partners

Maxime Gillet
Maxime Gillet

Postdoctoral fellow

Maxime Boivin

Professor, Department of Humanities and Social Sciences, Université du Québec à Chicoutimi

Co-Holder of the Chair for Research on Exploited Aquatic Species