Assessing bank erosion hazards along large rivers in the Anthropocene: a geospatial framework from the St. Lawrence fluvial system

Abstract

Over the past decades, riparian land-use changes coupled to the multiplication of river infrastructures have enhanced vulnerability issues for societies and ecosystems located along large rivers. Exposure to geohazards is also changing due to the ongoing climate change, underlining the need for flexible management strategies for riparian environments. In this perspective, GIS-based mapping allows integrating a wide range of environmental data. However, such datasets are often incomplete and not homogeneous over large geographical scales, which can be problematic for the implementation of regional land-use planning strategies. Using the St. Lawrence fluvial system (SLFS) (Québec, Canada) as a case study, this article reports and describes a high-resolution approach to map position, characteristics and erosion susceptibility of natural and artificial riverbanks from a combination of field-based, remote sensing and local knowledge-derived data. This approach allowed identifying erosion-prone sites and highlighting dominant erosion processes and spatially constrain them along the SLFS. The proposed geospatial framework constitutes (1) an initial portrait of the riverscape that will allow an effective implementation of future monitoring and process-based studies; and (2) a first step in supporting land-use planning stakeholders in the selection of appropriate measures to ensure a greater resilience of riparian communities and ecosystems.