Appropriate models and uncertainties

In analyzing complex problems in river or coastal zone management, use is often made of complicated models to simulate what happens under certain management options. For multi-disciplinary problems, the models can get very complex. It is not obvious that the most sophisticated model components should always be used. Rather, models should be as simple as possible, but no simpler. Such models could be called appropriate. In this paper, appropriate modeling is related to uncertainties in the output (decision) variables. These uncertainties should be small enough to allow a choice between management options. A procedure is proposed to arrive at such an appropriate model.