Recent advances in acquisition of spatial imagery have provided fluvial geomorphologists with increased possibilities for analyzing riverine landscapes and estimating hydraulic parameters - from the computation of critical metrics, such as river width, depth, and velocity to the assessement of fluvial habitat quality and dynamics. However, this poses the problem of efficiently extracting large amounts of imagery data along an organized, spatial continuum. This study develops a geographical information system (GIS) approach for the automated extraction of raster data organized within a single-part, elongated linear polygon of variable width. More specifically, we provide a robust, user-friendly, open-source toolbox that allows users to perform data retrieval following a single branch river centerline, inputted as simple vector object. The Fluvial Geomorphology toolbox comprises four ArcGIS Python scripts,‘Create Transects, ‘Moving Window’, ‘Local Moving Window’ and ‘Distance Along Line (DAL)’ that each generate respective sets of geometrical or tabular outputs on which information can be manipulated. ‘Create Transects’ creates perpendicular transects along a centerline, ‘Moving Window’ creates a series of overlapping aggregated geometries that export raster data to text files, ‘Local Moving Window’ creates a series of geometries, delimited by point couples, that export raster data to text files and ‘DAL’ calculates cumulative distances of given objects along a centerline. This toolbox was used to assess the effect of hydro dams on rivers at the scale of Canada.