Development of a fuzzy logic-based rainfall-runoff model

Rainfall-runoff models are used to describe the hydrological behaviour of a river catchment. Many different models exist to simulate the physical proc esses of the relationship between precipitation and runoff. Some of them ar e based on simple and easy-to-handle concepts, others on highly sophisticat ed physical and mathematical approaches that require extreme effort in data input and handling. Recently, mathematical methods using linguistic variab les, rather than conventional numerical variables applied extensively in ot her disciplines, are encroaching in hydrological studies. Among these is th e application of a fuzzy rule-based modelling. In this paper an attempt was made to develop fuzzy rule-based routines to simulate the different proces ses involved in the generation of runoff from precipitation. These routines were implemented within a conceptual, modular, and semi-distributed model- the HBV model. The investigation involved determining which modules of this model could be replaced by the new approach and the necessary input data w ere identified. A fuzzy rule-based routine was then developed for each of t he modules selected, and application and validation of the model was done o n a rainfall-runoff analysis of the Neckar River catchment, in southwest Ge rmany.