We examine the geomorphological width functions of several river basins through the formalism of conservative (microcanonical) random cascades and we compare the results with those of more conventional fractal and multifractal analyses. We suggest that the spatial patterns of aggregation described by the width functions analyzed show common recurrent characters and that the implications of the robust identification of the singularity spectra via Legendre transforms are supported also by random cascade rationale. ¿ American Geophysical Union 1994