Gully system development and an assessment of gully initiation risk in Miocene deposits near Daroca : Spain

A 25 km2 area in Spain near Daroca (Zaragoza province), consisting of Miocene gravelly loamy deposits of mainly lacustrine origin, suffers locally from severe ravine and gully erosion. A method is proposed for distinguishing between several gully generations within one gully or ravine system. The maximum slope steepness of the site, the length of the slope measured from the local waterdivide to the lowest part of the segment with the steepest slope, and the gravel content of the surface layer are useful variables to separate gully from non-gully sites in the study area. Linear discriminant analysis was used to combine these three variables into one function for optimum separation between gully and non-gully sites.