The use of fuzzy logic in the field of hydrological forecasting is a relatively new area of research and the potential to enhance river study by incorporating this soft computing methodology still remains to be exploited. Unlike mathematical model that require precise knowledge of all the contributing variables, fuzzy logic, on the other hand, offers a more flexible, less assumption dependent and self-adaptive approach to modelling river related processes, which by this nature are inherently complex, non-linear and dynamic. This book imparts latest development in fuzzy rule-based modelling effectively in the hydrological processes. It deals with the possibilistic criteria in modelling river catchment processes and water resources analysis with promising results. It is very needful for researcher of river dynamic systems and students of water resource management, flood control, land used planning with mathematical promises.