Geological models used in predictive hydrogeological modeling are not exact replicas of the objects they represent: many details related to structures and properties of the objects remain unknown. Those details may considerably affect simulation results. A provable evaluation of the uncertainty of hydrogeological and solute transport simulations are almost impossible. In this book the author describes how to obtain the best-possible results in simulations, based on the available data and predefined criteria that are turned into transforming mechanisms. The latter are mathematical expressions...