To evaluate the aggressiveness power of cavitating flows and to improve prediction methods for cavitation erosion, the pressure waves emitted during bubble collapses were studied and simulated by means of the Keller's and Fujikawa and Akamatsu's physical models. The profile and the energy of the pressure waves emitted during cavity collapse were evaluated by numerical simulation. The dynamic response and the surface deformation (i.e., pit profile and pit volume) of various materials exposed to pressure wave impacts was simulated making use of a 2D axisymmetric numerical code simulating the interaction between pressure wave and an elastoplastic solid. Making use of numerical results, a new parameter β (defined as the ratio between the pressure wave energy and the generated pit volume) was introduced and evaluated for three materials (aluminum, copper and stainless steel). By associating numerical simulations and experimental results concerning pitted samples exposed to cavitating flows (volume damage rate), the pressure wave power density was introduced. This physical property of the flow characterizes the cavitation aggressiveness and can be related to the flow hydrodynamic conditions. Associated to β parameter, the pressure wave power density appeared to be a useful tool to predict the cavitation erosion power.