Abstract
Conceptual hydrological models imply a simplification of the complexity
of the hydrological system; however, it lacks the flexibility in
reproducing a wide range of the catchment responses. Usually, a
trade-off is done to sacrifice the accuracy of a specific aspect of the
system behavior in favor of the accuracy of other aspects. This study
evaluates the benefit of using a modular approach, “The fuzzy committee
model” of building specialized models (same structure associated with
different parameter realization) to reproduce specific responses (high
and low flow response) of the catchment. The study also assesses the
applicability of using predicted runoff from both specialized models
with certain weights based on a fuzzy membership function to form a
fuzzy committee model. This research continues to explore the fuzzy
committee models first presented by [Solomatine, 2006] and further
developed by [Fenicia et al., 2007; Kayastha et al., 2013]. In this
paper, weighting schemes with power parameter values are investigated. A
thorough study is conducted on the relation between the fuzzy committee
variables (the membership functions and the weighting schemes), and
their effect on the model performance. Furthermore, the Fuzzy committee
concept is applied on a conceptual distributed model with two cases, the
first with lumped catchment parameters and the latter with distributed
parameters. A comparison between different combinations of the fuzzy
committee variables showed the superiority of all Fuzzy Committee models
over single models. Fuzzy committee of distributed models performed
well, especially in capturing the highest peak in the calibration data
set; however, it needs further study of the effect of model
parameterization on the model performance and uncertainty.