Analysis of conceptual rainfall-runoff modelling performance in different climates

With the objective of studying conceptual rainfall-runoff modelling perform ance in different climates, the HBV-96 model was applied on four catchments located in Europe, Africa and South America. Manual, automatic and Monte C arlo techniques were used for model calibration and parameter analyses. It was found that the magnitude of the water balance components had a signific ant influence on model performance. Performance decreased and demands of ca libration period length increased with increased catchment dryness primaril y because of a neater water balance and higher climatic variability in drie r areas. A large degree of equifinality was discovered in all catchments wh ere different calibration methods yielded equally good results but with dif ferent parameter combinations. Thus, it may be impossible to know if an opt imum parameter set exists and to relate parameter values to physical proper ties of the catchment. On the other hand the validation results indicated t hat it might not matter if parameter values were not unique when studying r unoff solely, provided the model application is within the same regime of f lows. (C) 2000 Elsevier Science B.V. AU rights reserved.