The susceptibility of a topsoil to erode under the impact of rain during a “flash flood” phenomenon is associated to its aggregate stability and in alpine environment landslides are enhanced whenever soil aggregates disintegrate and disperse. The aggregate stability dynamic of soils has been successfully evaluated and valdated(Zanini et Al. 1998; Freppaz et. Al. 2002) under water-saturated conditions by the exponential equation y(t)=a [1-exp(-t/c)]+b. Parameter a is the maximum estimated abrasion loss of aggregates; b the incipient failure of the aggregates when saturated in water and c a parameter that links the rate of aggregate breakdown to wet-sieving time. The proposed equation conceptually refers to a system where dry aggregates at the soil surface are wetted, flooded and subjected to the disruptive action of both the flowing water and the eroding particles being suspended and carried in the water runoff. The net amount of disintegration is then limited by the actual content of coarse primary particles, and it is determined by the progressive breakdown caused both by dissolution of bonding substances and mechanical abrasion of particles. The equation was applied to experimental data from 132 samples using a wide range of Italian topsoils from NW Alps. The parameters satisfactorily accounted for variations among the soils based upon soil type, parent material and land use. Our objective was to maintain the uniqueness of each breakdown curve and yet reduce the kinetic variability between soils to only one scale factor. Scale factors could potentially be related to the pedo-environmental conditions most likely influencing aggregate stability and connected soil hazards. Here we used a scaling method termed functional normalization (Miller, 1980) that is a regression procedure by which scale factors for soil processes are determined from sets of experimental observations. The scaling factors defined a scale mean curve for the aggregate breakdown of all the soils. The magnitude of the scaling factor gives a unique quantitative estimate of aggregate stability (the larger its value, the greater is the aggregate stability) for each soil while the particular values of parameters a, b and c describe the kinetics of aggregate breakdown. The scale factors significantly depends upon the forest cover, the soil lithology as well as the topography. The scale factors can be used to quantify and sort the kinetics of soil structure stability amongst a large number of soils while maintaining the particular values of parameters a, b and c for each soil equation describing the kinetics of aggregate breakdown and the incipient failure of the pre-wetted aggregates.A new breakdown kinetic from a new topsoil inserted in the data base can modify the scaling factor data set fixing the exact relative position of this soil versus the new scale mean curve that is consitent with the “mean hazard” of the area. Freppaz M., Lunardi S., Bonifacio E., Scalenghe R. e Zanini E. (2002). Advances in GeoEcology 35, Catena Verlag, Reiskirchen, Germany, pp.125-132. Miller, E.E. 1980. In D. Hillel and D.E. Elrick (eds), Scaling in Soil Physics: Principles and Applications. Soil Sci. Soc. Am., SSSA Spec. Publ. No. 25, Madison, WI, pp. 300-318. Zanini E., Bonifacio E., Albertson J. D., Nielsen D.R. (1998). Soil Sci., 163, 288-298.