Optimization methods for the evaluation of the parameters of a rockfall fractal fragmentation model

In rockfall events, the falling blocks impacting the slope can experience fragmentation due to their kinetic energy. This process produces new blocks, smaller than the initial ones, moving along independent trajectories. As a result, the in situ block size distribution (related to the slope face of the source area) and the rockfall block size distribution (related to the deposit) differ. The present paper proposes and compares two optimization procedures for choosing the parameters of an iterative fractal fragmentation model based aimed at describing the rockfall fragmentation process on the base of source and deposit block distributions. To discuss the effectiveness of each approach, the two distributions are considered free of uncertainties. The influence of the number of iterations and optimization approach are discussed in terms of easiness of interpretation of the results.