Global climate change is likely to increase temperatures, change precipitation patterns and probably raise the frequency of extreme events. Impacts of climate change on river flooding may be considerable and may cause enormous economical, social and environmental damage and even loss of lives. This necessitates the application of robust and accurate flood estimation procedures to provide a strong basis for investments in flood protection measures with climate change. A broad palette of models is available to fulfil this requirement. More complex models generally have larger data requirements and computational costs, but may result in smaller model output uncertainties and associated costs. It would seem that an optimum complexity associated with minimum total costs or uncertainty exists. This raises the question what such an appropriate model should look like given the specific modelling objective and research area. Or which physical processes and data should be incorporated and which mathematical process formulations should be used at which spatial and temporal scale, to obtain an appropriate model level? Therefore, the main objectives of this study are the determination of the appropriate model complexity dependent on modelling objective and research area and the assessment of the climate change impact on river flooding with an appropriate model. The Meuse basin in Belgium and France serves as an application area in this thesis. The first objective is dealt with in chapter 2, 3, 4 and 5 and constitutes the main part of this thesis. The second objective is mainly treated in chapter 4 and 6.