Assessment of erosion risk due to rainfall at regional scale

At present soil erosion represents an unsolved problem and each year it causes severe economical and environmental damages, in term of loss of production, as welle as loss to society of a natural resource. It is then crucial to evaluate the erosion risk, so adopting the erosion control practices. Particularly at regional level, the availability of thematic maps representing the variability of risk on the whole territory, can allow to adopt the suitable interventions to reduce the amount of soil losses. Rainfall can be considered as one of wthe main variables for the intensity of this process, due to the impact of water drop on soil particles. On these bases the rainfall factor of the universal soil loss equation has been determined, as approximately by Arnouldus (1980), for the Tuscany area, using rainfall historical series of about of 100 weather stations. Puncutal data have been interpolated all over the region applying the conventional multi-regressive analysis and the locally calibrated multivariate regression. Method performances have been compared considering correlation coefficients and residuals. Results have been discussed to evaluate the accuracy of each method and the eventual trend of risk distribution on the regional areas.