Modelling Uncertainty in Flood Forecasting Systems outlines a framework and supplies tools and techniques for uncertainty modeling in flood forecasting systems. After identifying the need for uncertainty assessment and to distinguish types and sources of uncertainty in flood forecasting, the author reviews the theories of uncertainty representation and customary methods of uncertainty modeling, explores the advantages and possibility of hybrid techniques of uncertainty modeling and probability-possibility (or fuzzy) transformations, and demonstrates computer codes to implement the developed methodology and to validate them by application to real-world problems.