Topographic and vegetative influences on flood susceptibility in Toronto: A GIS based approach

This study investigates the influence of topography and vegetation coverage on flood susceptibility across the City of Toronto, with a focus on variations between floodplain and non-floodplain areas.  Using spatial analysis tools in ArcGIS Pro, and statistical modeling in RStudio, the research integrates Digital Elevation Model (DEM) data to derive slope, alongside NDVI (Normalized Difference Vegetation Index) values obtained from Landsat imagery.  Results reveal that floodplain areas exhibit significantly higher NDVI values (mean = 0.3299) compared to non-floodplain areas (mean = 0.2265), suggesting greater vegetation cover in flood-prone zones.  Topographically, floodplain regions are steeper, with a mean slope of 3.4649, versus 2.1391 in non-floodplain areas.  The Downtown Core, in particular, demonstrates low NDVI values (mean = 0.1552) and flat terrain (mean slope = 1.3861), increasing its vulnerability to surface flooding due to limited natural absorption and poor drainage.  These findings indicate that areas with lower NDVI and flatter slopes face heightened flood risk, especially during extreme precipitation events.  The study underscores the need for integrating greenspace expansion and terrain-aware planning into flood mitigation strategies in urban environments.  Limitations include resolution discrepancies between datasets and absence of temporal flood occurrence data.  Future research should incorporate dynamic rainfall and socioeconomic vulnerability data to develop a more holistic flood risk model for Toronto.