Good Modelling Practice keywords: simulation modelling process, modelling life-cycle, quality-assessment, evaluation of modelling products

Introduction Modeling and simulation is nowadays a standard tool in the toolbox of many workers in the different fields of applied sciences. In The Netherlands several hundreds of modelers are involved in modelling for water management. But modelling might be a routinely applied method to investigate problems, it is not straightforward, but rather subjective, depending on the modelling team and its skills. Therefore one often refers to it as to the ‘art of modelling’. This artistic and creative label sounds as a positive designation, but it stresses the unscientific and ambiguous aspects of modelling.